1.23

Object

Representation ID: 3568

Received: 11/08/2021

Respondent: Mr Robin Elder

It is noted that in Table 2.5 of the document “Bedford Borough Transport Model New Settlements and the A6” prepared by AECOM, provides the statement presumably specified by BBC “Traffic calming and urban realm - The aim of this intervention is to calm and slow down traffic, primarily on roads that are non-strategic routes…….”. It is a lost opportunity in any forward looking plan not to extend traffic calming to Bedford Town Centre and all residential approach roads including the strategic routes. This would be in-line with more progressive Councils such as London where TfL (Safe speeds for central London – introducing 20mph speed limits - Transport for London - Citizen Space (tfl.gov.uk)) are imposed a 20mph zone on many roads and specifically involving the strategic routes and often without engineered calming ensuring compliance (as the Police prefer). Towards the end of 2020 the Police undertook a traffic survey on Shakespeare Road which demonstrated that even in a lockdown residents suffered 8,500 vehicles a day exceeding what the Police defined as a safe maximum speed. Residents need and expect more ambition.

It is assumed from the documents that the “A6 Settlements” have largely already been dismissed by the Council and that a significant reason for this is the consequent additional congestion at the Clapham Road/Manton Lane/Shakespeare Road junction as highlighted in the AECOM report mentioned above. This raises the existing traffic problems in the area which require attention. Residents in this area want to see less traffic and the remaining traffic moving slower bringing back the avenue feeling to the area.

Support

Representation ID: 3802

Received: 26/08/2021

Respondent: Mr Paul Woolmer

Infrastructure is already in place for this development.
The development would almost exclusively benefit Bedford commence & industry.
This is by far the best option for a new major housing development.

Object

Representation ID: 3952

Received: 29/08/2021

Respondent: Mr Mark Potts

Development north of Bedford has been ruled out because of the capacity constraints on the A6.
However, the traffic studies conducted already show that the capacity on the A6 will be exceeded
when you include the existing development planned for Local Plan 2030. Since then Bedford
Borough Council have specified that the new East West rail station must be in Bedford town centre
so the issues on the A6 need to be resolved even without further development north of Bedford.
Therefore infrastructure funds from a new development could contribute to this.
In addition the AECOM transport modelling is fundamentally flawed.

Support

Representation ID: 3987

Received: 29/08/2021

Respondent: Mrs Sharon Woolmer

It makes sense to use the infrastructure in this area and the new people moving in would benefit Bedford for shopping etc

Object

Representation ID: 4142

Received: 30/08/2021

Respondent: Mr paul giles

Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.

In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 4157

Received: 30/08/2021

Respondent: Mrs MARGARET TURNER

Development north of Bedford has been ruled out because of the capacity constraints on the A6.
However, the traffic studies conducted already show that the capacity on the A6 will be exceeded
when you include the existing development planned for Local Plan 2030. Since then Bedford
Borough Council have specified that the new East West rail station must be in Bedford town centre
so the issues on the A6 need to be resolved even without further development north of Bedford.
Therefore infrastructure funds from a new development could contribute to this.
In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 4220

Received: 30/08/2021

Respondent: Mrs Gerardine Meola

A6/Manton Lane junction must be resolved, to ensure residents north of Bedford can access new EWR hub in Bedford. Development at Twinwoods (brownfield) could contribute to funding improvements.

A Park & Ride scheme and compulsory purchase of a portion of the school playing fields on Manton Lane for improved road network could help resolve issues.

Colworth was previously an adopted option and A6/Manton Lane junction was not a problem then - why now when further improvements have been made in the interim. The Council is not being consistent in its decision making.

Object

Representation ID: 4422

Received: 31/08/2021

Respondent: Miss Andrea Witham

Development north of Bedford, such as at Twinwoods, has been ruled out because of capacity issues on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when the existing development planned for Local Plan 2030 is included . Since then BBC has specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even if there is no further development north of Bedford. Infrastructure funds from a new development could contribute to this.

Object

Representation ID: 4459

Received: 31/08/2021

Respondent: Mrs Lucy Crawford

Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.

In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 4485

Received: 31/08/2021

Respondent: Mr Andrew Murray

This entire report appears to have been constructed with a predetermined conclusion to provide evidence AGAINST development north of Bedford along the A6. Why has no similar report been produced for other major A-roads, for example the A421 or A6 to the south of Bedford?

Object

Representation ID: 4535

Received: 01/09/2021

Respondent: Mrs Kathryn Smith

Development north of Bedford has seemingly has been ruled out because of the over capacity on the A6.
However, the traffic studies already conducted show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030.
Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre therefore the issues on the A6 need to be resolved to accommodate this.... even without further development north of Bedford.
Therefore infrastructure funds from a new development to the north of Bedford could contribute to this.

Object

Representation ID: 4620

Received: 01/09/2021

Respondent: Mr Melvyn Chase

This should include a more accurate survey of the agricultural land grades – particularly in the areas where larger sites are proposed for development. Soil and agricultural land is an important consideration according to the NPPF.

Object

Representation ID: 4681

Received: 01/09/2021

Respondent: Mr Joshua Zwetsloot

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. Staploe Parish Council believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows: (Table 3.15 attached here)
You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume1capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.
• 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.

Object

Representation ID: 4727

Received: 01/09/2021

Respondent: Professor Michael Jeferson

The most serious flaw in the draft Local Plan 2040 comes in the “Bedford Borough Transport Model: New Settlements and the A6”. This comment focuses on proposals for Colmworth, although some aspects may also apply to Twinwoods. The “Results” of the transport “model” provide “2040 ‘Without’ Mitigation” Scenario B: 2,400 new dwellings at Colmworth only; and Scenario C: 3,495 new dwellings at Twinwoods and 2,400 new dwellings at Colmworth. This is followed by: “2050 ‘Without’ Mitigation” Scenario B: 4,500 new dwellings at Colmworth only; and Scenario C: 5,940 new dwellings at Twinwoods and 4,500 new dwellings at Colmworth. Access to and from this proposed Colmworth development is assumed to be via Souldrop and the Forty Foot Lane without mitigation, or in the “with mitigation” scenario via improved link roads. This Report anticipates almost a 30% increase in traffic, on top of an increase of almost 15% from 2018 to the 2030 reference case. (3) No consideration appears to have been made of whether an exit route north-westwards towards Wellingborough would be feasible, or its visual and other impacts on the fine landscape along any proposed such route. There is also no reference to prospects for the Santa Pod race track which, given efforts to move to a UK Net Zero emissions position by 2050, suggest either closure or alternative usage – such as testing of EV vehicles.
The proposals for Colmworth in the draft Local Plan 2040 appear to have ignored the debate which occurred between 2016 and 2020 on the earlier Colmworth Garden Village proposal – which met with heavy local adverse criticism (for example: BBC News, Beds, Herts & Bucks: “Colmworth Garden Village homes could be built on ‘unspoilt countryside’”, January 11, 2018). The result then was: BBC News: “Bedford Borough Council local plan approved after new village scrapped”, January 9, 2020.
In short, the draft Local Plan 2040 has completely ignored the Bedford Borough Council’s priorities for the Colmworth area as set out for Zone 1, (as mentioned in rep relating to rep for para 1.35) Its location by the Three Shires Way and Forty Foot Lane does not receive a mention. Its consequences for traffic movements by Souldrop, for the A6, and any efforts to move directly towards Wellingborough appear to have been ignored.
Plans for future development north of Bedford urgently need serious review and re-evaluation, whether of housing or the proposed Ox-Cam rail route, or the whole Arc concept as far as North Bedfordshire is concerned. Bedford Borough Council need to be much more aware of the potential of North Bedfordshire for quiet rural pursuits, especially rambling, and to promote them more, instead of endangering the area with ill-considered development.

Object

Representation ID: 4742

Received: 01/09/2021

Respondent: Mr David Rawlins

Development north of Bedford, such as at Twinwoods, has been ruled out because of capacity issues on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when the existing development planned for Local Plan 2030 is included . Since then, BBC has specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even if there is no further development north of Bedford. Infrastructure funds from a new development could contribute to this.

Object

Representation ID: 4859

Received: 02/09/2021

Respondent: Ms Tara Skey

Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when the existing development planned for Local Plan 2030 is included. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.

Object

Representation ID: 4932

Received: 02/09/2021

Respondent: Mrs Julia Willison

Development north of Bedford has been ruled out because of the capacity constraints on the A6. The traffic studies carried out show that the capacity on the A6 will be exceeded when you include the existing development planned for local plan 2030. Since then Bedford borough council have specified that the new East West rail station must be in Bedford town centre so the issue on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from the new development could contribute to this. In addition the AECOM transport modelling is flawed.

Object

Representation ID: 4936

Received: 02/09/2021

Respondent: Mr Chris Giles

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. Staploe Parish Council believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
•
•

•

• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.
• 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.

Object

Representation ID: 5485

Received: 06/09/2021

Respondent: Mr Stuart Ledwich

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. Staploe Parish Council believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:





• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volumecapacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail statoin. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030. Bedford Borough Council will have to solve this – not the developers of Twinwoods.
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.
• 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.

Object

Representation ID: 5579

Received: 06/09/2021

Respondent: Mrs Julie Kilby

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
•

•

• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.


• 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.

Object

Representation ID: 5607

Received: 06/09/2021

Respondent: Milton Ernest Parish Council

The Parish Council note the paper - Bedford Borough Transport Model - New Settlements and the A6 and wish to make the following observations.

The community of Milton Ernest has to endure increasing numbers of vehicles travelling through the heart of its village. It remains the only significant settlement between Luton and Finedon that has not received any form of mitigation for the ever-increasing volume of traffic using the A6 corridor.

Increased noise, pollution and negative impact on social well-being continues to blight the lives of our community. There is no regard within the mentioned report on the impact upon the community, simply whether the road network has the capacity to take even greater numbers of vehicles, should either Colworth or Twinwoods be developed.

Even without the potential ‘new settlement’ developments, current housing growth, on all sides of the village, creates greater and greater number of vehicle movements both day and night, which need to be mitigated.

Milton Ernest Parish Council recognise the Borough’s need to deliver growth, however, the impact and needs of those most affected by such growth can not be overlooked or simply dismissed. We therefore recommend further discussion and inclusion of the alleviating mitigation measures mentioned within the report, whether or not either site is approved for development. And most definitely before any such development commences.

Object

Representation ID: 5629

Received: 07/09/2021

Respondent: Mr Phillip Yockney

Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.

In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 5682

Received: 07/09/2021

Respondent: Miss amber scally

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. Staploe Parish Council believe that conclusion is incorrect.
● The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
● One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
● Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
●

●

● You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
● The report at paras 3.5.21 and 3.5.22 states:
● 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volumecapacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
● 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
● The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
● It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
● Para 4.2.9 concludes :
● 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
● This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.


● 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.

Object

Representation ID: 5733

Received: 07/09/2021

Respondent: Miss Hannah Hambleton-Jewell

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
•

•

• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.


• 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.

Object

Representation ID: 5762

Received: 07/09/2021

Respondent: Mrs Gillian Tagg

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e., congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows: (extract from document inserted)
• The black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore, this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly since all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.

• 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 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.
100-word Summary
Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when the existing development planned for Local Plan 2030 is included. Since then, Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Infrastructure funds from a new development could contribute to this.
In addition, the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 5841

Received: 08/09/2021

Respondent: Mr Norman Hoy

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows: (Table inserted here)
• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volumecapacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.


• 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.
100 word summary
Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.
In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 5915

Received: 08/09/2021

Respondent: Mr Tom Tagg

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:
• General: No validation or calibration of the traffic model has been undertaken which is not in keeping with Department for Transport guidance.
• 2.4.2 Despite employment land being allocated in the BBC options, AECOM have assumed that no employment has been assumed to be associated with the proposed developments. This underestimates the journeys of employees and delivery vehicles to/from the sites.
• 2.4.3 AECOM have not applied site-specific trip rates but have adopted trip rates using a DfT model (CTripEnd). This results in “around 20 to 25 outbound car vehicle trips in the AM peak hour,”. The Colworth and Twinwoods development scenario options range between 2,500 and 10,440 houses. With a likely 2 cars per household, i.e. up to 20,880 cars, allowing only 20-25 cars is clearly a gross underestimate of the number of outbound car vehicle trips in the AM peak.
Given these, all of the assessments undertaken by AECOM to determine the rerouting, vehicle km travelled, junction delays and junction-capacity ratios for any scenario are highly unlikely to be representative.
4.5.21 and tables 3.15, 3.16, show that in the reference case (2030) 3 of the 4 arms of the Clapham Road/Manton Lane junction are at (100%) or above (104%) full capacity leading to significant delays. It should be much better highlighted that this is before any new Local Plan 2040 developments are considered in the model. This is therefore a BBC problem that arises from the developments allocated in the current 2030 Plan (even including the planned highways mitigations to 2030) that needs resolving independently of the Local 2040 plan. When added to the 2030 model the Twinwoods development only has a marginal impact on these junction capacity ratios, increasing these by a maximum of 3% to 107% of capacity.
4.5.22 Confirms that no mitigation has been proposed for the congestion at this junction – due to physical constraints of buildings and schools. This is unacceptable, as it effectively means that the brownfield site of Twinwoods is not therefore considered as a site for development.
4.2.9 Concludes that without a solution to the congestion and delays at the Clapham Road/Manton Lane junction, delivery of growth along the A6 corridor will be constrained. BBC need to find a solution to this – BBC are content to demolish houses to bring EWR to Midland road – maybe similar extreme action is required in this case to open up development in the north of the borough.

Object

Representation ID: 5961

Received: 08/09/2021

Respondent: Staploe Parish Council

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect and that previously there have been some proposal put forward!
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows: (Extracts inserted here.)
• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volume capacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods (Brownfield site) is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.
• 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.
100 word summary
Development north of Bedford has been ruled out because of the capacity constraints on the A6. However, the traffic studies conducted already show that the capacity on the A6 will be exceeded when you include the existing development planned for Local Plan 2030. Since then Bedford Borough Council have specified that the new East West rail station must be in Bedford town centre so the issues on the A6 need to be resolved even without further development north of Bedford. Therefore infrastructure funds from a new development could contribute to this.
In addition the AECOM transport modelling is fundamentally flawed.

Object

Representation ID: 6001

Received: 08/09/2021

Respondent: Mrs Christina Farmer

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. I believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
•

•

• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volumecapacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.


• 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.

Object

Representation ID: 6096

Received: 09/09/2021

Respondent: Jen Giles

BBC have concluded that Twinwoods creates such a traffic problem at the Clapham Road/Manton Lane junction in Bedford that it is not a suitable development site as the developer has not proposed a solution to the congestion at that junction. Staploe Parish Council believe that conclusion is incorrect.
• The transport model starts with the 2018 base year model previously developed and then adds to that the growth identified by Bedford Borough Council in the adopted local plan to 2030 and includes the mitigations (traffic schemes) that are planned to happen by 2030. This then creates the reference case at year 2030, against which the different development scenarios to 2040 and to 2050 are compared.
• One of the measures of the impact the developments will have on the highway network, is the Junction-Volume Capacity Ratio. This shows how congested the junctions will be – so a figure of 100% means that the junction is fully utilised, i.e. congested, leading to delays at that junction.
• Tables 3.15 (for 2040) and 3.16 (for 2050, but incorrectly titled for 2040) show the Junction-Volume Capacity Ratios for the PM peak Hour in 2040 and 2050 for the unmitigated and mitigated Twinwoods scenarios. The 4 lines for the Clapham Road/Manton Lane junction as follows:
•
•

•

• You will see that the black boxes denote 100% or more Ratio – i.e. the junction is completely full (on 3 of the 4 legs) and congested.
• The report at paras 3.5.21 and 3.5.22 states:
• 3.5.21 Table 3.9 to Table 3.16 highlight that there is forecast to be significant delays and congestion issues at the Clapham Road / Manton Lane Junction, particularly in the PM Peak hour. These forecast delays and high volume-capacity ratios are present within the 2030 reference case, with volume-capacity ratios forecast to be above 100% on three out of the four arms at this junction. These high forecast volumecapacity ratios are maintained or are forecast to worsen in the 2040 and 2050 forecasts including the proposed Twinwoods and / or Colworth developments.
• 3.5.22 As part of the forecasting assumptions for the reference case (see Table 2.2), an improvement scheme at this location, which provides a dedicated left-turn lane for Clapham Road southbound traffic to Manton Lane and the part-signalisation of the roundabout, is included. Further mitigation at this location was considered as part of this study to alleviate the forecast congestion, but due to the constraints at this location (such as existing buildings and Bedford Modern School) no further mitigation has been proposed as part of this study.
• The junction is already completely full at 2030 before any new developments or the addition of an east west rail station in Bedford Town Centre. Therefore this is a Bedford Borough Council problem that will already happen due to the growth in the adopted Local plan 2030 (1500 new homes all north of Bedford which will impact the A6 by 2030). Bedford Borough Council will have to solve this – not the developers of Twinwoods but a development at Twinwoods might contribute some infrastructure funding to help mitigate the problems on the A6
• It should be noted that when Twinwoods is included the Junction-Volume Capacity Ratios increase (on 3 of the 4 legs) from 100% to between 101% and 105% which is negligible in the overall scale of the issue.
• Para 4.2.9 concludes :
• 4.2.9 Significant forecast delays and capacity constraints are forecast at the Clapham Road / Manton Lane roundabout in northern Bedford, primarily in the PM Peak hour, both in the reference case and with the inclusion of the proposed developments and mitigation measures. The reference case includes improvements to this junction; however, further mitigation at this junction to alleviate the forecast congestion has not been proposed as part of this study due to the physical constraints at this location. Without further capacity improvements or measures to reduce the forecast traffic at this location, the forecast congestion at this junction is likely to be a constraint on the delivery of growth along the A6 corridor to the north of the borough.
• This demonstrates that this is not a new development issue, but an existing issue that Bedford Borough Council will have to solve before 2030 – particularly in view of the fact that all traffic wanting to access the new East West Rail Station from the north of the Borough will need to use the A6 to reach the station in central Bedford.
• 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.