A concept image of the extradosed W膿iti River Crossing (Image: Vinci)

A consortium comprising HEB Construction, Fulton Hogan, Aurecon and Tonkin & Taylor has secured a NZ$510 million (US$315 million) contract for the new 艑 Mahurangi-Penlink expressway in North Auckland, New Zealand.

The 7km-long Penlink roadway will connect the Whangapar膩oa, Hibiscus Coast and Silverdale regions, as part of an NZ$8.7 billion (US$5.2 billion) government project to upgrade the county鈥檚 infrastructure.

The consortium was appointed to the project by New Zealand鈥檚 transport agency Waka Kotahi, and will be responsible for design and build of the expressway, which will comprise two bi-directional traffic lanes and a shared mobility lane for pedestrians and cyclists.

Construction of the Penlink expressway, which is due to be completed in 2026, will see the erection of six new bridges - including an extradosed bridge that will span the Auckland鈥檚 W膿iti River. 

With reducing carbon emissions and minimising the environmental impact of the project a key concern for the transport authority Waka Kotahi, its national manager for infrastructure delivery, Mark Kinvig, said, 鈥淲aka Kotahi identified that the W膿iti River Crossing would be the largest single contributor to Penlink鈥檚 embodied emissions, so exploring innovative solutions and ways to reduce its carbon footprint was a strong focus for the alliance during the procurement process.鈥�

With a structure that combines the main elements of both a prestressed box girder bridge and a cable-stayed bridge, the design and build methods chosen by the consortium for the extradosed bridge aim to 鈥渞educe carbon emission by up to 20% compared to a conventional design鈥�. 

Vinci, parent company of HEB Construction, said, 鈥淭he lowered entrance to the extradosed bridge by 550m will be integrated into the landscape while reducing the total length of the bridge by 235m and, in fact, the amount of steel and concrete used. The crossing was designed with two piers instead of three in the W膿iti River.鈥�

The company added, 鈥淐onstruction will be carried out protecting local flora and fauna through upstream studies and continuous monitoring throughout the duration of the work.鈥�