1.26

Object

Representation ID: 6712

Received: 14/09/2021

Respondent: Mrs Elizabeth Froude

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 6750

Received: 14/09/2021

Respondent: Ms S Kelly

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 6802

Received: 15/09/2021

Respondent: Mr Damian Smith

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 6850

Received: 13/09/2021

Respondent: Mrs Joanna Ibbett

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
[PARAGRAPH 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT]
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 6889

Received: 15/09/2021

Respondent: Master Corey T Farmer

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7019

Received: 17/09/2021

Respondent: Mr Robert Tusting

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7070

Received: 09/09/2021

Respondent: June Coles

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7117

Received: 09/09/2021

Respondent: Stephen Coles

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7197

Received: 17/09/2021

Respondent: Mr Peter Knight

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7284

Received: 01/09/2021

Respondent: Miss Laura Jones

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
SEE TABLE IN ATTACHMENT
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 7494

Received: 03/09/2021

Respondent: Mr Jonathan Hambleton

odels that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 7555

Received: 21/09/2021

Respondent: Mr malcolm whitehouse

I could not find a reference to the footway provision in the North Beds Villages nor could I find any mitigation measures to reduce the traffic through and between villages. The roads between villages are already eroded at the margins where vehicles pass each other caused by the high volume of vehicles using the byways. The Borough has not considered the use of the 2006 quiet lanes legislation in these areas. Most villages in North Beds do not have adequate footways and in many cases no footways at all. These plans will make the rural environment even more dangerous for walkers, cycling and equestrian users.

Object

Representation ID: 7603

Received: 01/09/2021

Respondent: Miss Nicola Tagg

Please refer to my detailed response to 1.25 above.

1.26 100-word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 7650

Received: 01/09/2021

Respondent: Mr Simon Goodship

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
SEE SECTION 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON SETTLEMENT

Object

Representation ID: 7745

Received: 22/09/2021

Respondent: Mr Michael Thompson

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The TEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
SEE SECTION 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT

It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary
The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 7805

Received: 03/09/2021

Respondent: Mr Emilio Meola

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 7844

Received: 03/09/2021

Respondent: Mr Mark Ibbett

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.

SEE SECTON 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT

It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 7948

Received: 24/09/2021

Respondent: Ms Lorraine Jewell

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.

PARAGRAPH 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT


It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8006

Received: 24/09/2021

Respondent: Mr Larry Gooch

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.

PARAGRAPH 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT

It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Support

Representation ID: 8041

Received: 24/09/2021

Respondent: North Northamptonshire Council

It is noted that since the publication of the Issues and Options consultation in August 2020, Bedford Borough Council have developed the Bedford Borough Transport Model (BBTM) (a multi-modal transport model), to test the proposed Local Plan development scenarios for forecasts in 2030, 2040 and 2050. The results of this scenario testing has been used to inform the preferred options presented.

We welcome that the transport model built includes the highway network in North Northamptonshire Council, to enable us to understand the distribution of forecast traffic flows from each of the development options tested and any impact on the highway network within North Northamptonshire.

The preferred options presented (Option 2a, Option 2b, Option 2c, Option 2d) all have an urban focus, with growth concentrated around the A421, railway based growth with various options around new settlements.

We note that the transport modelling shows that the preferred options result in an increase of forecast flows concentrated in the vicinity of Bedford with the least impact on the highway network relative to the other options tested. Moreover, the transport modelling concludes that mitigation should be achievable to mitigate the forecast flows to an acceptable level in highways terms but that there will be some congestion and delay.

We note that the transport modelling concluded that the Colworth and Twinwood new settlements resulted in significant congestion and delay on the A6 approach to Bedford from the north and that additional mitigation has not been identified to address this delay.

We also note that page 29 of the Development Strategy Topic Paper states that in ‘the absence of currently deliverable railway stations at either location which might make an impact, the capacity issues here are too great to allow further development on the A6 (north) corridor such as the new settlements proposed at Twinwoods and / or Colworth.’

Following careful consideration of the Bedford Borough Transport Model New Settlements and the A6 report we also note the following:
• A higher proportion of traffic from Colworth is forecast to travel north to Rushden than south to Bedford (to access the A14)
• Despite the increase in traffic flows, the transport modelling seems to suggest relatively minor impacts on the A6 junctions around Rushden compared to the 2030 reference case. Our transport modelling suggests that the A6 particularly south of Rushden is becoming constrained. A new settlement at Colworth would compound this.
• There is forecast to be some rat-running to use the A509 (and presumably on to Milton Keynes)
• We note that the trip rates used are average trips rates and may not represent the most robust worst case
• We note that the new station at Colworth has been included as a mitigation measure in the transport modelling for the A6 settlements, however the Development Strategy Topic Paper notes that this railway station is undeliverable. This therefore suggests that the traffic modelling may be underestimating the forecast flows on the A6 if the railway station is not a deliverable mitigation and as a result, the impact on the highway network.
• We note that a super cycle highway is proposed from Colworth to Bedford. The distance from Sharnbrook to centre of Bedford is around 9 miles, so this would be around a 45-minute cycle for the average person cycling, less with an e-bike. Further details on how many trips are expected to use this, the proposed route and its deliverability would be welcomed.

In light of the above, it is clear that the transport modelling has identified some unacceptable highway impacts of the new settlements proposed on the A6 corridor. We therefore support alternative development scenarios being taken forward that are able to be mitigated in highway terms.

Object

Representation ID: 8112

Received: 03/09/2021

Respondent: Dr Emma Thompson

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
(see paragraph 2.4.3 of New Settlement West of Wyboston document)
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8151

Received: 03/09/2021

Respondent: Mr Ross Thomson

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
(see paragraph 2.4.3 of New Settlement West of Wyboston document)
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8190

Received: 03/09/2021

Respondent: Mrs Bernadette Yockney

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8249

Received: 03/09/2021

Respondent: Mr Daniel Francis

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
(see paragraph 2.4.3 of New Settlement West of Wyboston document)
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8293

Received: 03/09/2021

Respondent: Miss Erin Francis

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
(see paragraph 2.4.3 of New Settlement West of Wyboston document)
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8434

Received: 03/09/2021

Respondent: Mr Theodore Cassell

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
see para 2.4.3 of New Settlement West of Wyboston document.

It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary
The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8608

Received: 13/09/2021

Respondent: Mr Henry Zwetsloot

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.
[PARAGRAPH 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT]
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

Object

Representation ID: 8767

Received: 29/09/2021

Respondent: Staploe Parish Council

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.

SEE PARAGRAPH 2.4.3 OF NEW SETTLEMENT WEST OF WYBOSTON DOCUMENT

It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.

1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8801

Received: 28/09/2021

Respondent: Mrs Nicola Gooch

1.26 Bedford Borough Transport Model Local Plan Assessment Report – AECOM
The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document. Para 2.4.3 states


No site specific trip rates have been applied within this assessment of the proposed Dennybrook development, with trip rates defined within CTripEnd (the DFT's trip end model underpinning its National Trip -End Model (NTEM) forecasts ) adopted. These represent 'average' trip rates and in general result in around 20 to 25 outbound car vehicle trips in the AM peak hour, which may be below the trip rates assumed as part of a detailed development assessment.
It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.
1.26 100 word summary

The transport model used by AECOM is fundamentally flawed because the model has not been validated / calibrated (particularly with respect to public transport), the National Trip End Model (NTEM) should not be used below district / county level, no uncertainty log has been prepared, it doesn’t include household survey data, and the data has not been adequately tested. Strategic models are not designed for use in a scheme specific assessment. The latter requires a revised forecast model produced from a recalibrated base year model using additional and more recent data with a more specific geographical focus of resources and modelling.

Object

Representation ID: 8928

Received: 01/10/2021

Respondent: Mr James Browning

The Transport Modelling undertaken by AECOM in support of the strategic options in the Draft Local Plan 2040 is fundamentally flawed for the following reasons.
No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport WebTAG guidance.
It is assumed that the Bedford Borough Transport Model was undertaken using Saturn, which was the model of choice for the Bedford Town Centre modelling project in 2015. In this case, Saturn cannot directly Model Public Transport therefore it is assumed that the engineers have made some significant assumptions with respect to public transport and trips being used, which have not been validated or calibrated.
TAG unit M1.2 introduces the National Trip End Model (NTEM). It includes forecasts of population, households, workforce and jobs over 30 years which are used in a series of models that forecast population, employment, car ownership, trip ends and traffic growth by Middle Layer Super Output Area (MSOA). The NTEM data set can be viewed using the TEMPro (Trip End Model Presentation Program) software. TEMPro estimates of trip ends at any level below aggregate regions (e.g. MSOA, district, or county level) are subject to uncertainty and should not be used as constraints in matrix development process without verification and possible adjustments. No uncertainty log was prepared which is a recommendation of WebTAG modelling guidance.
For direct use in matrix development, trip rate information estimated from household survey data should be considered instead to underpin trip end estimates at zone level. There is a risk that model may not be realistic or sensible due to the error around the model parameters used, or limitations in the extent to which the model can represent human behaviour. Therefore, before using any mathematical model, it is essential to check that it produces credible outputs consistent with observed behaviour. This is usually done by running the model for the base year (either the current year or a recent year), and:
• comparing its outputs with independent data (validation);
• checking that its response to changes in inputs is realistic, based on results from independent evidence (realism testing); and
• checking that the model responds appropriately to all its main inputs (sensitivity testing).
Five types of data can be collected and used to inform most models:
• data on the transport network, including the physical layout, number of lanes, signal timings, public transport frequencies and capacities;
• counts of vehicles or persons on transport services, links or at junctions;
• journey times;
• queue lengths at busy junctions;
• interview surveys, in which transport users are asked to describe trips either through household travel diaries or intercept surveys (e.g. roadside interviews, public transport onboard interview surveys.
These types of checks have not been undertaken to validate / calibrate the model.
AECOM have derived trip ends using CTripEnds for a number of journey purposes. Expanding synthetic trip ends produced by CTripEnd to the local zoning system is considered to be subject to significant discrepancies from observed especially if validation and the calibration exercise has not been undertaken.
It is also important to note that strategic models are not designed for use in a scheme specific assessment. For such an assessment it is recommended a revised forecast model would be produced from a recalibrated base year model using additional and more recent data and targeted to reflect a more specific geographical focus of resources and modelling effort.

As part of the Bedford Borough Transport Model documents it is quoted that average departing trips are 20 to 25 vehicles, which may be below the trip rates assumed as part of a detailed development assessment. The extract below is taken from the New Settlement West of Wyboston document.



It is unknown what scenario of Dennybrook (site 977) development that the above “20 to 25 outbound car vehicle trips in the AM peak hour” relate to, however an outbound TRCS residential trip rate is somewhere between 0.23 to 0.33 vehicles per dwelling.
The development scenario ranges from 2,500 dwellings to 10,150 dwellings. On this basis and using a 0.25 departure trip rate results in 625 to 2,538 departing trips all of which would be home based departure trips. The model assumes 5 loading zones which therefore means there could be 125 to 508 vehicles per loading zone. This is significantly higher than the 20 to 25 outbound vehicle used by the AECOM model, assuming they have loaded it per node.
AECOM may claim that some of the departing trips will be internal and therefore will not cross cordon line however taking the 125 departing vehicle trips associated with 2,500 dwellings scenario; 20% of these departing vehicles are considered not to be leaving the area. This percentage decreases further if the worst case number of dwellings is being considered, i.e. 10,150 dwellings. It has previously been highlighted that the AECOM model has not be validated / calibrated and now given the apparent significant under valuation of the likely vehicle trips that will be generated, it is clear that the assessment of the capacity of junctions and the highway network is fundamentally flawed.
The significant undervaluation of generated vehicle trips could be argued by AECOM as being a reduction due to the impact of the public transport. However, the proposed new railway stations associated with the East West Rail Link are located to the east of the A1, which is significantly far enough away for the Dennybook development to be considered to not directly serve it without requiring a vehicle car trip to be generated. In this scenario it more likely that occupiers of Dennybrook (site 977) dwellings will continue their journey by car as opposed to transferring onto rail.
Given this all of the assessments undertaken by AECOM to determine the rerouting and vehicle km travelled for any scenario are highly unlikely to be representative.
Town planning principles are that new development should be centred on and around existing sustainable urban area where local infrastructure exists and allow residents to travel using public transport to serve the development which can be easily extended.
If larger new settlements are the only realistic option then they should be centred on transport hubs such as a new railway station so that they become the heart of the community and the de facto mode of travel. Locating a new settlement on the edge of town / out of town where the transport hub is also not well connected leads to a disjointed sustainable public transport which will always be second best to car travel.