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Columba Park, Sandon

Expert witness support for large-scale employment space, with iTransport brought onboard specifically to support the Appeal process.

Overview

iTransport was appointed in June 2025 specifically to support the planning appeal as Transport & Highways expert witness. Our brief: peer‑review the earlier third-party submission, prepare a vision‑led Transport Assessment Addendum (TAA) to align with the updated NPPF, lead technical dialogue with Essex County Council (ECC) and National Highways (NH), and provide formal Proof of Evidence to the Inquiry.  

Columba Park is an outline proposal for up to 46,605 sqm of mixed employment space (E(g)(iii), B2, B8), with access for determination and other matters reserved, on land by the A12 Junction 18 / A414 Maldon Road at Sandon. The appeal was lodged against non‑determination, with Chelmsford City Council setting a putative reason for refusal around highways: alleged insufficient information to demonstrate no unacceptable safety impact and no severe residual cumulative impact, and lack of clarity on sustainable travel infrastructure—referencing NPPF (2024) paragraph 116. 

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Our approach

Throughout, we coordinated closely with Counsel and the core team, focusing the evidence on the NPPF tests: prioritising sustainable modes; securing safe and suitable access; and demonstrating no ‘severe’ residual impacts following mitigation.  

Acting as transport expert witness, Neil Marshall led a rapid technical refresh and evidential strategy: 

  • Peer review of the application transport work and production of a Transport Assessment Addendum to implement the NPPF’s vision‑led, scenario‑testing approach (Business‑as‑Usual, Sustainable Vision, and High Sustainability), including multi‑modal demand, updated distributions, and corrected junction modelling.  
  • Proof of Evidence setting out policy compliance, the appeal site’s sustainable access strategy, and a consolidated response to the putative refusal grounds.  
  • Targeted engagement with ECC & NH post‑appeal, delivering three technical response notes to close evidence gaps: Paramics microsimulation of the Maldon Road corridor (linked signals + J18 roundabouts), slip‑road merge/diverge assessments against the >30 veh/hr trigger, and clarifications on trip rates, staff origins, and sensitivity testing.  
  • Access & active‑travel package: a new signalised A414 site access with toucan crossings, over 800 m of new shared foot/cycleway along A414, controlled crossings on the J18 roundabouts, and a new active‑travel bridge over the A12 to Sandon Park & Ride—advanced to Approval‑in‑Principle level for Inquiry certainty. 
  • Risk management: agreeing the modelling platform, study area, growth, and tests with both highway authorities, and capturing the resultant positions within a Topic SoCG (Highways).  

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Outcomes & Impact

After reviewing our evidence — including the updated modelling, design refinements, and sustainable travel improvements — both Essex County Council and National Highways withdrew their objections. They confirmed that, with normal planning conditions, there are no remaining transport or highways issues. 

This resolution significantly lowered the appeal risk for the client and provided the Inspector with a clear, robust basis to conclude that Columba Park meets national policy tests and should not be refused on transport grounds. Ultimately, at the appeal the Inspector agreed with the position, upholding the appeal within a month of the Inquiry closing.

Our work demonstrated clearly that Columba Park can be safely accessed and operated without causing major traffic problems on the surrounding roads. 

Using industry‑standard modelling (essentially a highly detailed virtual version of the local road network), we showed that: 

  • Traffic will continue to flow smoothly through the junctions around A12 Junction 18, even with the development in place. Delays were shown to be small — usually only a handful of seconds, and well within what drivers experience naturally from day to day.  
  • The A12 slip roads have plenty of space to hold traffic at busy times, with queues remaining well within the lengths designed for those roads — meaning no risk of traffic backing up onto the A12 itself. 
  • The new signalised access onto the A414 works efficiently and doesn’t interrupt traffic heading to or from the A12. 
  • The upgraded walking and cycling routes, combined with a new bridge over the A12, create safe, direct links to Sandon Park & Ride and the surrounding communities, giving future staff and visitors genuine alternatives to driving.  
  • The local bus network already offers frequent, reliable services, and the development’s improvements will make them even easier to reach. 

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We provide the full range of specialist transport planning services needed to take schemes from early concept through to consent and delivery

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Being brought on to the project as expert witness is testament to iTransport's skill and expertise, being able to pick up the work of others and critically review this, speak plainly to clients and deliver successful outcomes.
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