Traffic Planning for Gateway to the North: State Highway 1 Realignment Case Study

Traffic Planning Consultants (TPC) assessed the feasibility of a proposed State Highway 1 realignment north of Auckland, known as Gateway to the North (GTTN). The route aimed to bypass the Brynderwyn Hills and was evaluated as an alternative to NZTA’s shortlisted options. TPC’s assessment confirmed GTTN as technically viable, with a shorter route, lower environmental impact, and better use of existing infrastructure, leading to its inclusion in NZTA’s shortlist for further investigation.

Summary

Project Overview

Client: Private landowner consortium
Location: North of Auckland – State Highway 1 corridor
Scope: Feasibility assessment for highway realignment as an alternative to NZTA’s proposed Brynderwyn bypass options
Challenges: Aligning with NZTA’s Business Case process, assessing multi-criteria performance, and demonstrating cost-effectiveness and network resilience

Our Approach

Strategic Business Case Alignment
TPC applied the NZTA Business Case methodology to ensure the Gateway to the North proposal could be robustly assessed alongside the Agency’s shortlisted alternatives. This included adopting a consistent framework for evaluation of safety, resilience, and journey time performance.

Route Planning and Technical Analysis
A high-level concept design was developed using GIS to analyse the physical feasibility of the proposed alignment. Planning constraints and environmental considerations were also identified to inform route refinement.

Performance Assessment and Cost Estimation
We conducted a multi-criteria performance review against NZTA’s investment objectives and produced a cost estimate to support decision-making. The results demonstrated that GTTN offered significant benefits in terms of reduced travel distance and infrastructure efficiency.

Key Outcomes

GTTN identified as a technically feasible and cost-effective alternative
Shorter route length than the existing SH1 and NZTA’s proposed bypasses
Lower visual and noise impacts compared to other alignment options
Adopted NZTA’s evaluation methodology for direct comparability
NZTA included GTTN in the shortlist of options for further investigation

Exploring transport infrastructure alternatives or early-phase route feasibility?
Traffic Planning Consultants deliver strategic expertise in Transportation Planning and Traffic and Transport Modelling to support high-impact transport decisions.

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