Transport Technical Paper [EXAM 114]
(8) 1. Introduction
(2) 1.1 Purpose
1.1.1 This technical note has been produced as a response to the matters raised by the Inspectors in EXAM 69, in relation to transport. It covers issues relating to the strategic transport network, particularly the impacts of development proposed within the Local Plan on J11a and J13 of the M1. Issues raised by the Inspectors relating to access / transport of individual housing or employment sites have been addressed within the relevant Housing and Employment Technical Papers (EXAM 113 and EXAM 112, respectively).
(1) 1.2 Key Evidence Studies
1.2.1 There have been two stages to the technical evidence prepared on transport matters for the Local Plan prior to the Examination hearing sessions, and a further series of junction modelling post the hearings.
1.2.2 The first is the strategic transport modelling, which provided a high-level cumulative assessment of road network performance (at peak times) and highlighted those 'hotspot' locations where congestion levels and junction delays as a result of the proposed local plan growth had impacts on the highway network. As well as early consideration of the impact of the overall growth strategy, the work then considered the strategic housing and employment, and small to medium site allocations. The following documents were prepared:
- ED C24: Stage 1a (July 2017) Assessment growth scenarios for the Regulation 18 submission
- ED C25: Stage 1b (Jan 2018) Confirmed the network issues (i.e. 'hot spots') identified in Stage 1a for CBC's preferred growth scenario, using an updated version of the transport model.
- ED C26: Stage 1c & 1d (Jan 2018) Identified the highway network constraints (i.e. 'hot spots'), with and without Local Plan growth, for Forecast Years 2025 and 2035 (i.e. the end of the Plan period); and identified potential cross-boundary impacts of the Local Plan growth. Following this, this stage identified the traffic to/from the strategic housing and employment sites and their potential cross-boundary impacts; and assessed, at a high level, the potential contribution of these strategic sites to the 'hot spots' identified in Stage 1c.
- ED C27: Stage 2a (Jan 2018) Proposed highway and public transport mitigation options for the confirmed 'hot spots' as identified in Stage 1c, published at Regulation 19, including conceptual design.
- ED C28: Stage 2b & 2c (April 2018) Tested the mitigation identified in Stage 2a and identified additional hotpots, caused by the rerouting of traffic as a result of the proposed interventions, which led to the identification of additional mitigation to deal with new hotspots and the retesting of all mitigation schemes as a full mitigation package.
1.2.3 The second part of the work was the preparation of a Mitigation Feasibility Study (EXAM 7S). This built on previous work by developing and testing the viability of potential mitigation design options at seven identified sites on the Strategic Road Network (SRN). These seven sites were agreed with Highways England (HE) as the key 'hotspots' for mitigation prior to commencing work. This study outlined baseline and future junction performance; identified and tested potential scheme options to mitigate the impact of Local Plan growth (2035); and selected a preferred viable mitigation, based on the information available. Local junction modelling has been used to compare the future operational performance of the potential mitigation schemes and the key outcomes of this are reported.
1.2.4 M1 J13 was not included within the hotspot locations mitigation work as it was decided due to the complicated layout of this junction that a micro- simulation model would be built by Highways England to understand how the junction operated and what mitigations might improve its operation sufficiently to accommodate the Local Plan growth.
1.2.5 Following the examination hearings, detailed junction modelling for both M1 J13 and M1 J11a has been undertaken to add clarity to understanding the impact of the Local Plans growth in these locations.
1.2.6 At M1 J13 a VISSIM model has been developed by Highways England to support understanding of how this complicated junction operates, and from this, a series of potential mitigation options have been modelled. A similar process has been followed by CBC for M1 J11a to support the M1-A6 Link Road planning application. Further details of both these assessments are discussed later in this paper.