Box Hill Intersection Safety Improvement

The brief

The Box Hill Intersection has been one of the most traffic- and safety-concerned locations within Wellington City. Wellington City Council commissioned TTAP to lead the safety improvement project from initial optioneering through to detailed design for construction.

What we deliver

A multi-stage safety improvement spanning the full design lifecycle:

Community, stakeholder and inter-departmental engagement to surface user-perceived risk and operational constraints
Optioneering — long-list options development, multi-criteria analysis, stakeholder engagement, engineering design, and identification of the preferred option
Traffic simulation modelling in Aimsun, supporting option evaluation with measurable operating performance against the do-minimum baseline
Detailed design for construction — the preferred option taken through to constructible engineering documentation

Annotated aerial of the Box Hill intersection in Wellington City showing existing geometry, proposed traffic-management interventions, sight-line constraints and legend. — Annotated aerial of the Box Hill intersection — existing geometry, proposed interventions, and the engineering markup used through optioneering.

How we work

Safety projects of this kind sit at the intersection of community concern and operational performance — neither dominates. We led the technical engineering while keeping the engagement strand running in parallel, so the preferred option was both modelled-defensible and community- acceptable before it ever reached detailed design.

Outcome

The preferred option was identified, modelled in Aimsun, and progressed to detailed design for construction. The evidence trail — long-list analysis, MCA scoring, community input record, Aimsun outputs, and constructible design package — is the audit-ready record WCC needs to defend the investment decision.

Team

Bob Hu (Managing Director / Principal Traffic Engineer) led the project. Simon Cager (Principal Project Engineer) chaired the optioneering and detailed-design phases. Stu Zhang (Transport Modeller) built and calibrated the Aimsun micro-simulation. Charles Agate (Senior Assets Engineer / Traffic Management Specialist) led traffic-management design. Ana Wang (Senior Project Manager) coordinated community and stakeholder engagement across council departments and the wider Box Hill catchment.

For safety improvements on your network, talk to us.