A park for AgriTech, Hinxton Further Addendum to the Environmental Statement SmithsonHill New technical appendix J2: TN01 Traffic Modelling Report Terence O’Rourke Ltd 2019 35 A Planning Appeal by SMITHSONHILL LIMITED In respect of A Park for AgriTech, HINXTON Traffic Modelling Report August 2018 A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report DOCUMENT SIGNATURE AND REVIEW SHEET Project Details Project Title: A Park for AgriTech, HINXTON Project No.: 1803-72 Report No.: 1803-72/TN/01 Client: SmithsonHill Limited Prepared By: Checked By: Approved for issue Giovanni Di Guardo / Name Rupert Lyons Daniel Ekstrand Daniel Ekstrand Signature GDG / DE RTBL DE Date 20/8/2018 20/8/2018 22/8/2018 Document Review Revision Date Description Checked By Issued by: Bristol Transport Planning Associates Cambridge 25 Southampton Buildings London London Manchester WC2A 1AL Oxford Welwyn Garden City 020 3709 9405 [email protected] www.tpa.uk.com 1803-72/TN/01 Transport Planning Associates August 2018 i A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report CONTENTS PAGE 1 NON-TECHNICAL SUMMARY 1 2 INTRODUCTION 4 The Purpose of this Technical Note Traffic Modelling Assumptions 3 IMPACT ASSESSMENT 10 Delay Assessment 4 RESIDUAL IMPACT FOLLOWING MITIGATION 13 Enhanced Off-site Highway Works Stage I Road Safety Audit Junction Capacity Assessments (with enhanced off-site highway works) Delay Assessments (with enhanced off-site highway works) 5 SENSITIVITY TESTS 25 Wellcome Traffic Flows Uttlesford Sensitivity Flows (from ABA Transport Assessment) Junction Capacity Assessments (Sensitivity test with enhanced off-site highway works) Delay Assessments (with enhanced off-site highway works) 6 CONCLUSIONS 30 1803-72/TN/01 Transport Planning Associates August 2018 ii A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report LIST OF TABLES Table 2.1 Trip Rates per Employee – Land Use B1 Table 2.2 Total Person Trip Rate – Land Use B1 Table 2.3 Multi-Modal development trips BAU Scenario Table 2.4 Vehicle Trip Distribution Table 3.1 Summary of Total Junction Delay in the Study Area (seconds per vehicle): ABA assessment Table 3.2 Summary of Total Junction Delay in the Study Area following model corrections (seconds per vehicle) Table 4.1 Junction Modelling Results - Junction 1 (M11) Table 4.2 Junction Modelling Results - Junction 2 (Hunts Road) Table 4.3 Junction Modelling Results - Junction 3 (Moorfield) Table 4.4 Junction Modelling Results - Junction 7 (A505 / A1301) Table 4.5 Junction Modelling Results - Junction 9 (A1307/ A11 Roundabout) Table 4.6 Junction Modelling Results - Junction 11 (A1301/ Site Access Road) Table 4.7 Summary of Total Junction Delay in the Study Area (summed across respective junction approaches expressed in seconds per vehicle or PCU): with TPA mitigation Table 4.8 Route Based Delay Results (seconds) Table 4.9 Comparison of the Delays between the TPA BAU scenario and the Future Base scenario Table 5.1 Sensitivity Test: Wellcome Genome Campus Trip Generation Table 5.2 Junction Modelling Results - Junction 1 (M11) Table 5.3 Junction Modelling Results - Junction 2 (Hunts Road) Table 5.4 Junction Modelling Results - Junction 7 (A505 / A1301) Table 5.5 Summary of Total Junction Delay Sensitivity Scope (summed across respective junction approaches expressed in seconds per vehicle or PCU) LIST OF APPENDICES A South Cambridgeshire District Council’s Refusal of Planning Permission Notice, dated 13 March 2018 B Enhanced off-site highway works C Designer`s Response Reports to Stage 1 Road Safety Audits D Modelling Outputs and Parameter Drawings E Sensitivity Test: TRICS Reports F Wellcome Genome Campus Trip Generation and Distribution 1803-72/TN/01 Transport Planning Associates August 2018 iii A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report LIST OF FIGURES Figure 2.1 Vehicle Trip Distribution Figure 4.1 Routes for route based delay comparison 1803-72/TN/01 Transport Planning Associates August 2018 iv A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report 1 NON-TECHNICAL SUMMARY 1.1 This Technical Note has been prepared by Transport Planning Associates in order to provide further analysis of the transport planning evidence base prepared by Alan Baxter Associates (ABA) and others on behalf of SmithsonHill in the context of the relevant reasons for refusal of SmithsonHill’s outline planning application to South Cambridgeshire District Council for a park for AgriTech in Hinxton. 1.2 The Council’s principal allegations are that: ñ the road network in this locality is already congested; ñ there is insufficient information in the ABA Transport Assessment to demonstrate the full extent of the development’s impact on the local highway network; ñ there is uncertainty on the impacts of the development on the strategic highway network; and ñ the applicant has not demonstrated that the scheme would have a satisfactory impact on the local highway network. 1.3 This Technical Note also provides additional analysis of the evidence base and considers alternative highway infrastructure improvement proposals to mitigate the transport impact of the proposed development. Traffic Modelling 1.4 As a first step, this Technical Note comprises a review of the traffic modelling assumptions employed in the transport planning evidence base to derive the scope and extent of the site access arrangement and the off-site highway works required to provide suitable vehicular access to, and to mitigate the traffic impact of, the proposed development. 1.5 We conclude that ABA’s derivation of existing and forecast base traffic flows is in accordance with good practice, although given the extent of the consideration of traffic associated with committed development, it is considered that the application of TEMPro growth factors is likely to be overly robust. 1.6 Our review of ABA’s traffic generation calculation reveals that ABA’s use of the TRICS-based methodology represents a reasonable worst case estimate of forecast peak hour development traffic flows. 1.7 Notwithstanding the commitment in the ABA Transport Assessment to achieve the Target mode share of 50% (of car drivers) through the active management of staff and visitor car parking and the provision and implementation of various travel planning initiatives, the traffic modelling and subsequent capacity analyses that inform the site access arrangement and off- site highway works required is based on a Business as Usual assessment that assumes that 1803-72/TN/01 Transport Planning Associates August 2018 Page 1 of 30 A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report 79% of person trips to and from the proposed development will be made by car drivers. Again, that is likely to result in an overly robust assessment. 1.8 ABA’s trip distribution has been calculated based on the Census Journey to Work data for the area where the site is located (South Cambridgeshire Middle Layer Super Output Area 017) and we consider that methodology is fit for purpose in accordance with conventional assumptions with regard to journeys to work. 1.9 The calibration and validation of the junction models employed in the ABA Transport Assessment are in accordance with the request of the Local Highway Authority. 1.10 ABA’s analysis indicated that an overall benefit was brought to the highway network following the ABA Transport Assessment proposals. However further investigation into the results revealed errors in the modelling and in the proposed designs. In light of this further analysis of the information contained in the ABA Transport Assessment was undertaken. Proposed Off-site Highway Works 1.11 Our review of the ABA proposed off-site highway works revealed some unnecessary departures from standards and our optioneering exercise determined some alternative strategies that will enhance the effectiveness of the proposed works. We have also identified some additional off-site highway works which fully mitigate the Business As Usual scenario. 1.12 The new proposed mitigation package has been subject to a Stage I Road Safety Audit. Further Traffic Modelling 1.13 Our further traffic modelling of an enhanced package of off-site highway works shows that the performance of the highway network within the study area would be significantly improved. Incorporation of that enhanced package of works delivers improvements (in the delay experienced by vehicles on the approaches to the junctions within the study area) of 56.5% and 75.3 % in the AM and PM peak periods, respectively. 1.14 Further analysis of three key routes through the study area reveals significant (circa 20-25 minutes) reductions in eastbound journey times during the AM peak period and in westbound journey times in the PM peak period. Sensitivity Testing 1.15 We have undertaken sensitivity testing of the junctions previously considered by ABA (that assumes the unmitigated traffic impact of the proposed Wellcome Genome Campus and North Uttlesford Garden Settlement developments). This reveals that: 1803-72/TN/01 Transport Planning Associates August 2018 Page 2 of 30 A Park for AgriTech, HINXTON SmithsonHill Limited Traffic Modelling Report ñ the approaches to Junction 10 of the M11 (Junction 1) continue to show improved performance when compared to the 2030 Baseline (do nothing scenario); ñ the approaches to the Hunts Road Junction (Junction 2) continue to show significantly improved performance when compared to the 2030 Baseline (do nothing scenario); and ñ with the