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DEVON COUNTY COUNCIL NORTH DEVON TRANSPORT MODEL LOCAL MODEL VALIDATION REPORT OCTOBER 2015 CONTENTS Page 1. INTRODUCTION 1 1.1 Introduction 1 1.2 Model Specification 1 2. NETWORKS 2 2.1 Highway Network 2 2.2 SATURN Coding 3 3. CALIBRATION & VALIDATION DATA 8 3.1 Traffic Growth 8 3.2 Traffic Counts 9 3.3 Journey Time Data 11 4. TRIP MATRICES 13 4.1 Highway Matrix Building Procedure 13 4.2 Car Trip Ends 13 4.3 Car Distribution 14 4.4 Matrix Building 18 4.5 Matrix Estimation 21 5. TRAFFIC MODEL CALIBRATION 27 5.1 Procedure 27 5.2 Highway Network 27 5.3 Traffic Assignment 30 5.4 Generalised Costs 30 5.5 Model Convergence 31 6. TRAFFIC MODEL VALIDATION 32 6.1 Validation Criteria & Acceptability Guidelines 32 6.2 Network Validation 33 6.3 Journey Time Validation 34 6.4 Validation at A361 Portmore RSI Site 36 6.5 Traffic Flow Validation 38 7. SUMMARY & CONCLUSIONS 39 TABLES Table 1: SATURN Junction Simulation Parameters for Extended Network ........................................... 3 Table 2: Traffic Growth ............................................................................................................................ 8 Table 3: Details of Traffic Counts ............................................................................................................ 9 Table 4: Average Journey Times .......................................................................................................... 11 Table 5: Model Time Period Factors ..................................................................................................... 14 Table 6: Calibration of Gravity Models .................................................................................................. 16 Table 7: Time Period Proportions ......................................................................................................... 18 Table 8: Composition of Initial Trip Matrices ......................................................................................... 20 Table 9: Matrix Adjustment to Cordon & Screenline Counts ................................................................ 21 Table 10: Initial Calibration of Trip Matrices .......................................................................................... 21 Table 11: SATME2 Results ................................................................................................................... 22 Table 12: Trip Matrix Totals After Matrix Estimation ............................................................................. 22 Table 13: WebTAG Matrix Estimation Performance ............................................................................. 23 Table 14: 2014 Sector Trip Matrices After Matrix Estimation ............................................................... 25 Table 15: 2013 PPM and PPK values ................................................................................................... 31 Table 16: Convergence Results – Base Year ....................................................................................... 31 Table 17: Screenline Flow Validation Criteria ....................................................................................... 32 Table 18: Link Flow and Turning Movement Validation Criteria ........................................................... 32 Table 19: Journey Time Validation Criteria ........................................................................................... 32 Table 20: AM Peak Journey Time Validation ........................................................................................ 34 Table 21: Inter Peak Journey Time Validation ...................................................................................... 34 Table 22: PM Peak Journey Time Validation ........................................................................................ 35 Table 23: Screenline Traffic Flow Validation ......................................................................................... 38 Table 24: Summary of Validation of Link Flows .................................................................................... 38 Table 25: Summary of Model Validation ............................................................................................... 39 FIGURES Figure 1: Barnstaple & Fremington Zones .............................................................................................. 4 Figure 2: Bideford & Northam Zones ...................................................................................................... 5 Figure 3: External Zones ......................................................................................................................... 6 Figure 4: Base Year Highway Network ................................................................................................... 7 Figure 5: Traffic Count Locations .......................................................................................................... 10 Figure 6: Journey Time Routes ............................................................................................................. 12 Figure 7: Calibration of Infill Gravity Models ......................................................................................... 17 Figure 8: Sector System ........................................................................................................................ 19 Figure 9: Trip Length Distributions ........................................................................................................ 24 Figure 10: Selected Modelled Routes ................................................................................................... 28 Figure 11: Sector Movements at RSI Sites 1 & 2 ................................................................................. 37 APPENDIX 1 – Time / Distance Diagrams APPENDIX 2 – Traffic Flow Validation LOCAL MODEL NORTH DEVON TRANSPORT MODEL VALIDATION REPORT 1. INTRODUCTION 1.1 Introduction 1.1.1 Devon County Council have updated the SATURN based transport model for Barnstaple and Bideford to inform their ongoing response and contribution to the joint Local Plan in order to identify transport schemes and measures to support the Local Plan. The aim of the transport study for Barnstaple and Bideford is to assess the impact of future development and identify appropriate transport infrastructure requirements. 1.1.2 The previous SATURN highway assignment model was developed for the working weekday AM and PM peak hours and an average inter peak hour, and has been updated to the new 2014 base year. The network and zoning was reviewed and extended to reflect the level of present trip generation and attraction and the likely future development areas. Validation was aimed to achieve near DMRB/Webtag critieria. 1.1.3 This report describes the development and validation of the updated base year transport model. The data presented shows that the model meets the required WebTAG validation criteria of networks, traffic flows, journey time, model convergence and trip distribution. 1.2 Model Specification 1.2.1 The detailed SATURN simulation area covers Barnstaple, Bishops Tawton, Landkey, Fremington and Yelland in North Devon District and Bideford and Northam in Torridge District. Other parts of Devon and the rest of the UK are included as external zones. 1.2.2 The updated SATURN based highway model has been developed for the following time periods in the 2014 base year: . AM peak hour (08:00 to 09:00 hrs); . Inter peak (IP) hour (average hour 10:00 to 16:00 hrs); . PM peak hour (17:00 to 18:00 hrs); 1.2.3 The model performs multiple user class assignment with the following user classes: . UC1 – Car - Commuting (COM); . UC2 – Car - Employer’s business (EMP); . UC3 – Car - Education (EDU); . UC4 – Car – Other purposes (OTH); . UC5 – Light goods vehicles (LGV); . UC6 – Other goods vehicles (HGV). NDevonNewModelLMVRV1 Page 1 October 2015 LOCAL MODEL NORTH DEVON TRANSPORT MODEL VALIDATION REPORT 2. NETWORKS 2.1 Highway Network 2.1.1 The previous SATURN highway network was extended to in the Bideford area with a more detailed network and a finer 166 zone system. Internal zones have been increased from 121 to 138 to include development zones in Barnstaple and Bideford, as shown on Figure 1 and Figure 2. The 28 external zones, Figure 3, have been retained but were linked to an external road network to replace traffic loading point zones on the external modelling cordon. 2.1.2 Link information was obtained for sections of similar characteristics, including: . Width . Number of lanes . One or two-way . Central reserve width (if any) . Extent of kerbside parking (if any) . Extent of bus lane, times of operation, vehicle types . Speed limit . Location of bus stops . Location of controlled and uncontrolled pedestrian crossings . Lane and road markings 2.1.3 Junction information was collected for all junctions, including: . Type of junction . For each approach no. of lanes and widths and lane length for short approach lanes . Lane and road markings indicating turning movements . Stop lines and give way lines . Prohibited turns . For traffic signals - cycle times, no. and length of stages, intergreen times, pedestrian phases, permitted movements for each stage etc. 2.1.4 Highway link and junction details were obtained from: . Devon County Council’s highway information GIS data; . Traffic signal data from Devon County Council; . Site visit and Google aerial mapping to check for completeness and for recent changes. NDevonNewModelLMVRV1 Page 2 October