A joint venture between Downer and Seli (an Italian specialist tunnelling contractor) undertook the construction of a cable tunnel in Auckland for client Mercury Energy (which later became Vector) between 1997 and 2000. The Engineer for the contract was Tonkin & Taylor who undertook the detailed design and contract supervision.

The contract consisted of approximately 9kms of 3.0m diameter tunnelling with 3 primary shafts and several minor shafts providing network access to the city for power supply cabling. The tunnel follows an alignment from the Hobson Street substation in the CBD and then under public streets until it meets with the State Highway 1 southern motorway where it continues to the Grid Exit Point at Penrose.

The Northern Gateway Alliance, which includes Transit NZ, Fulton Hogan, Leighton Contractors, URS, Tonkin Taylor and Boffa Miskell, completed construction of the first road tunnels in 30 years as part of the $360M ALPURT B2 Project in early 2009, one of New Zealand’s largest infrastructure projects.