Waterview project hits halfway

Waterview Junction has made good progress over the past months. Photo / Nick Reed.

Homeward stretch for motorway connection designed to take pressure off Auckland Harbour Bridge.

New Zealand's largest road project - the $1.4 billion Waterview Connection in Auckland - has passed the halfway mark now that two of the traffic ramps for its giant motorway-to-motorway interchange are completed.

That milestone follows a start on the second of two triple-lane tunnels between the future interchange at Waterview and a surface extension of the Southwestern Motorway to Owairaka 2.4km away.

The Transport Agency is trumpeting the completion of the longest of four ramps that will deliver traffic to and from the tunnels, ramps that together will form 1.7km of viaducts in a three-level interchange rising 23 metres above the Northwestern Motorway.

Most of the piers for the two remaining ramps are already in place and they are due for completion by October next year, with the whole project scheduled for completion early in 2017.

The overall project will provide a 4.8km link between the two motorways and complete the 47km western ring Manukau-Albany route, an alternative to the harbour bridge.

A proposed $450 million link with State Highway 1 at the top end is due for completion by 2020.

A workforce of about 860 people from the Well-Connected Alliance (NZTA and contractors) and its subcontractors has sweated almost 5.5 million hours into the project, which began in early 2012.

A prefabrication plant in East Tamaki was built to churn out more than 24,000 concrete rings, each weighing about 10 tonnes, to line the 13.1m diameter tunnels, the largest in Australasia.

An extra $600 million is being spent on widening the Northwestern Motorway from Western Springs to Te Atatu, including raising the marine causeway west of Waterview and enlarging three existing interchanges, to cope with extra traffic heading to and from the tunnels.

The agency expects 71,000 vehicles a day through the tunnels from opening time in April 2017, rising to 96,000 by 2026, and is building towers to vent exhaust fumes at each end.