NEV – West of A419 supporting infrastructure – FBC New Eastern Villages – West of A419 supporting infrastructure Full Business Case Swindon Borough Council November 2020 NEV – West of A419 supporting infrastructure – FBC Contents 1. Introduction ............................................................................................................................................... 1-1 1.1 Background .............................................................................................................................................. 1-1 1.2 Scheme context ........................................................................................................................................ 1-1 1.3 Future developments ................................................................................................................................ 1-2 1.4 Purpose and structure of this report ......................................................................................................... 1-2 2. Strategic Case .......................................................................................................................................... 2-1 2.1 Overview of the Strategic Case ................................................................................................................ 2-1 2.2 Business Strategy..................................................................................................................................... 2-2 2.2.1 Policy and economic context .................................................................................................................... 2-2 2.2.2 The New Eastern Villages development .................................................................................................. 2-4 2.2.3 The NEV transport package ..................................................................................................................... 2-4 2.3 Planned changes to the transport network in Eastern Swindon .............................................................. 2-5 2.4 Traffic problems in the West of A419 area ............................................................................................... 2-6 2.4.1 Current and future traffic problems ........................................................................................................... 2-6 2.4.2 Impact of not changing ............................................................................................................................. 2-8 2.4.3 Collisions .................................................................................................................................................. 2-8 2.4.4 Summary .................................................................................................................................................. 2-9 2.5 Objectives and measures of success ....................................................................................................... 2-9 2.6 Options considered................................................................................................................................. 2-10 2.6.1 Oxford Road/Nythe Road junction ..........................................................................................................2-10 2.6.2 Piccadilly Roundabout ............................................................................................................................ 2-11 2.7 Project scope .......................................................................................................................................... 2-11 2.7.1 Oxford Road/Nythe Road junction ..........................................................................................................2-11 2.7.2 Piccadilly Roundabout ............................................................................................................................ 2-12 2.8 Scheme impacts and outcomes ............................................................................................................. 2-12 2.8.1 Oxford Road/Nythe Road scheme modelling ......................................................................................... 2-12 2.8.2 Piccadilly Roundabout scheme modelling .............................................................................................. 2-13 2.9 Constraints ............................................................................................................................................. 2-13 2.9.1 Utilities .................................................................................................................................................... 2-13 2.10 Interdependencies .................................................................................................................................. 2-14 2.10.1 Scheme packages .................................................................................................................................. 2-14 2.10.2 Planning .................................................................................................................................................. 2-14 2.10.3 Land ownership ...................................................................................................................................... 2-14 2.11 Stakeholders ........................................................................................................................................... 2-14 2.12 Summary of Strategic Case ................................................................................................................... 2-15 3. Economic case ....................................................................................................................................... 3-17 3.1 Introduction ............................................................................................................................................. 3-17 3.2 Transport modelling ................................................................................................................................ 3-17 3.2.1 SATURN modal and skims ..................................................................................................................... 3-17 NEV – West of A419 supporting infrastructure – FBC 3.2.2 TUBA assumptions ................................................................................................................................. 3-18 3.2.3 Annualisation factors .............................................................................................................................. 3-21 3.3 Model outputs ......................................................................................................................................... 3-21 3.3.1 Absolute differences in traffic flows ........................................................................................................ 3-21 3.3.2 Journey time information ........................................................................................................................ 3-23 3.3.3 Sensitivity tests ....................................................................................................................................... 3-25 3.4 Economy Impacts ................................................................................................................................... 3-26 3.4.1 Core Scenario – Public Accounts Impact ............................................................................................... 3-27 3.4.2 Core Scenario – Analysis of the Monetised Costs and Benefits ............................................................ 3-27 3.4.3 Core scenario – TAG data sensitivity test .............................................................................................. 3-28 3.4.4 User benefit context................................................................................................................................ 3-28 3.4.5 Reliability Benefits .................................................................................................................................. 3-30 3.4.6 Wider impacts and regeneration ............................................................................................................ 3-31 3.4.7 Comparison with OBC benefits .............................................................................................................. 3-31 3.5 Environmental impacts ........................................................................................................................... 3-31 3.5.1 Air Quality and Noise .............................................................................................................................. 3-32 3.5.2 Landscape and Visual Impacts .............................................................................................................. 3-32 3.5.3 Townscape ............................................................................................................................................. 3-32 3.5.4 Historic Environment .............................................................................................................................. 3-32 3.5.5 Biodiversity ............................................................................................................................................. 3-33 3.5.6 Water Environment ................................................................................................................................