Transport Technical Paper [EXAM 114]

The additional evidence produced by the Council fails to address the concerns set out by the Planning Inspector over the justification for, and soundness of, the allocation to the Marston Vale site. Specifically, we believe the following concerns should remain as ‘matters and issues’ and subject to examination at public hearings:
• Traffic impact cannot be sustainably managed for Marston Vale at the proposed scale and would be better achieved by utilising alternative sites.

• The allocation to Marston Vale should be reduced to 1,800 as a modification to make the submitted Local Plan sound pending the Council’s proposed ‘Early Review’ of the Local Plan which should address ‘material changes’ since the Plan was submitted in 2018 including reviewing housing needs and the distribution of development.

‘The additional modelling is clearly going to form a critical piece of evidence which directly relates to the location of the Plan’s largest allocation for up to 5,000 new homes at Marston Vale. In order to reach a robust, substantiated conclusion on the soundness of the Plan it would be necessary to consider the implications of the new evidence when it emerges and test it through further examination hearing sessions. In the absence of this modelling we continue to have reservations about the cross-boundary impacts which have been identified. In the context of an allocation for up to 5,000 new homes, we fail to see how the evidence is an accurate reflection of likely future transport pattern. In summary therefore, given the already high levels of congestion around Junction 13, and the planned level of growth nearby, the modelling is critical to understanding whether improvements can be undertaken that effectively mitigate the impact of additional development in this location.’
[Paras 46 - 48 of Planning Inspectors letter to Council September 2019 – Exam 69]
2.1 The additional evidence produced by the Council includes a new joint statement from CBC and HE concluding that ‘..in terms of highways impact on M1 J13, we have agreed the level of growth proposed within the local plan for this area can be accommodated.’ It also includes a more plausible forecast growth in traffic volume using the A421 to Milton Keynes. At issue then is whether the Inspector is content to accept this partial reassurance and the Council’s strategic modelling of the traffic impact of allocated development and proposed mitigation of ‘hot spots’ as sufficient evidence that the traffic impact could be sustainably managed.
2.3 The Planning Inspector will be aware that CBC continue to argue that that the strategic modelling they have carried out should be sufficient to judge the soundness of the development proposed in the Local Plan. In our view, an allocation of this scale on this site requires a higher level of confidence that the traffic impact can be sustainably managed. This is because of characteristics of the site and local factors which are not picked up in the modelling.
2.4 Data from the 2011 census (published by CBC as part of the Cranfield and Marston ward profile) recorded 7,540 cars linked to 4,720 dwellings (a ratio of 1.6:1). An allocation of 5,000 houses then might be expected (crudely) to increase the number of cars in this area by 7,987 (106%) or around double the current level. Even after allowing for a range of factors which would reduce that increase (including development since 2011, the mixed use nature of the site etc) it is clear that any adverse impacts from such a substantial net increase could be significant or severe.
2.5 Exam 114 concludes that the increase in traffic can by sustainably managed via mitigation to Junction 13 of the MI and by the committed dualling of the westward link of the A421. But there are substantial increases in traffic on other routes from the Marston Vale site. These are not visible in the strategic modelling within the submitted Local Plan or addressed by Exam 114. For example, the traffic assessment submitted by the developer in support of the planning application for Marston Vale forecasts increased traffic flows of 202% on the Lidlington High Street and Bury Ware link; 611% on Sheeptick End; 117% on the Station Road / Church Street link in Lidlington; 81% on Bedford Road in Marston; 34% on the C94 and 344% on The Lane / Marston Rd between Marston and Lidlington.
2.6 The developer’s transport strategy and travel plan outlines mitigation of the impact of the increased traffic in the AM and PM peak periods which they claim ‘demonstrates that the residual impacts of the Proposed Development on driver delay in the peak periods would not be significant’. That strategy and plan includes ‘demand management; improvements to the local public transport network and walking and cycling facilities; minor physical improvements to existing roads and junctions; and provision of new or expanded roads where necessary.
2.7 The 2011 census showed that 78% of economically active residents in the Cranfield and Marston ward travelled to work by car. 60% travelled to work outside Central Beds (to Milton Keynes, Bedford, and Luton mainly); 12% within Central Beds; and 28% within the ward. Only 6% walked to work; 4% used the train; 5% ‘other’ (including cycling) and 7% worked from home. The developer’s travel plan aims to reduce car use by -25%; increase bus journeys by 82%; rail by 38%; cycling by 68%; and walking by 4% [EIA Volume III Chapter 5 Appendix E Interim Travel Plan table 6.8].
2.8 There is nothing we have seen which would provide confidence that this development could demonstrate those levels of modal shift from cars and onto public transport, cycling or walking. The frequency (2 or 3 an hour), journey time (double that in a car) and likely cost of the proposed new bus services are unlikely to persuade sufficient people to leave their cars at home. The nearest rail transport hub will be at Ridgmont (the 2024 additional train services will not stop at Lidlington) which is beyond walking distance from the site.
2.9 A bus service and cycle lane to Ridgmont would require access to land which neither the developer nor the Council control. That new train service - as is the case now with the existing stopping service – does not go to where people travel to work (with the exception of Bedford) and at one train an hour in each direction does not support daily commuting involving connections at Bedford and Bletchley.
2.10 It seems unlikely that a sufficient proportion of the ~5,000 jobs on this mixed use site would be taken by people living on the site – at least not in the medium term and unless there was some kind of scheme linking affordable tenures to local recruitment. The developer’s assumptions about the effectiveness of the mitigation measures they propose are, in our view, over-optimistic.
2.11 Even if some meaningful modal shift could be achieved, there would still be significant increased traffic using local roads to access other routes and destinations. There are three roads which run across the site. Two of these merge 100yrds or so north of the level crossing at a point where traffic is expected to increase by 117% in the centre of Lidlington where the barriers will be down twice as often as they are now once the new train service starts in 2024. That road then merges with the third road via a T junction to a steep hill which joins the A507 at the Bury Ware T-junction where traffic is expected to increase by 202%, locally regarded as dangerous as it is close to a blind summit on a road which has a 50mph limit. The developer is proposing a new east-west ‘Cross-Vale’ road which aims to funnel traffic onto the C94, by-pass Marston and – along with other measures – deter traffic from going through Lidlington and Millbrook.
2.12 In a survey carried out in 2010 for the Parish Plan, 73% of residents reported experiencing ‘severe’ congestion on these local roads. Congestion occurs every time there is a significant increase in traffic – for example, because of incidents on the A421 / M1 or car boot sales in the locality.
2.13 This part of the Marston Vale experiences ‘temperature inversion’ events whereby cold air (and any air pollution) is trapped near the ground as warmer air moves above it from the Greensand Ridge which borders the area from the west and south. That increases the risk that any traffic congestion could lead to breaches in air quality and adverse impacts on public health. That, in turn, should increase the level of confidence required that the traffic impact can be sustainably managed to be sure this allocation is sound.