Hamilton Ring Road - Wairere Drive Extension and Cobham Drive Interchange

Hamilton City Council’s ambitious interchange project overcome significant challenges to complete the final connection of the Hamilton Ring Road.


Cobham Drive overbridge construction - Traffic diversion onto the future ramps to enable construction.

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Looking north towards the construction of the Cobham Drive bridge substructure.

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pocket park - Cobham Drive overbridge in the background.

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Cobham Drive overbridge.

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Cobham Drive road safety barrier - Peacocke Northern Pedestrian Bridge in the background.

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Pocket park - cultural expression on paving.

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Cobham Drive overbridge - Te Awa River Ride and stream diversion to the left.

The challenge

The Hamilton Ring Road – Wairere Drive Extension and Cobham Drive Interchange, is a $45 million Hamilton City Council / Waka Kotahi project. The extension provides the final connection of the Hamilton Ring Road between Cambridge Road and Cobham Drive. The Interchange with Cobham Drive is a full grade separated interchange, with Cobham Drive being raised to allow Wairere Drive to pass underneath.

BBO was engaged by Hamilton City Council to deliver the detailed design and construction monitoring of this project. From preliminary design through to the monitoring of construction, BBO was tasked with providing innovative solutions to deliver the project in a constrained site, wedged between a gully and a residential suburb, and dissected by SH1 carrying over 25,000 vehicles per day.

BBO rose to the challenge of managing a range of complex issues, including the discovery of contamination from the city’s historic World War 1 munitions factory; an asbestos dump site; the incorporation of Hamilton City’s future strategic water and wastewater pipelines; and significant service relocations including overhead power lines over the Waikato River.

The outcome

The Ring Road - Wairere Drive Extension and Cobham Drive Interchange project provides raised signalised intersections to improve safety - the first at a major arterial interchange in New Zealand.

All transport modes are provided for to access the new Waikato River Bridge and Peacocke Development, as are shared walking and cycling paths connecting to Hamilton Gardens, Te Awa cycleway, and surrounding parks and reserves.

A stream has been relocated to allow space for the interchange to be constructed. A key focus of the stream relocation and stormwater management was improving water quality to encourage the rejuvenation of wildlife. The stream features natural landscaping, rock and water features, as well as walking tracks weaving along the banks.

The project supports growth within Hamilton by opening up access to the Peacocke Growth Cell and provides both attractive and safe movement of all transport modes.

BBO has worked with Hamilton City Council, Waka Kotahi, and the Contractor to provide innovative and good value solutions. A key success factor for the project was keeping the many key stakeholders’ interests at the core of the project.