One last load of concrete and harbour link is as good as done

Auckland's duplicate motorway bridge over Manukau Harbour should be substantially complete this morning after a final overnight concrete pour to form a 650m link between the shores of Onehunga and Mangere.

The "final closure" pour of 34 cubic metres of concrete was to take place 25m above the harbour to connect the last two of the new bridge's eight spans, ready to carry four lanes of southbound traffic and a bus lane over an enhanced motorway link between Auckland and its airport.

That will leave the existing motorway bridge next to it for northbound vehicles once the $230 million project is completed by the end of August, doubling the harbour crossing's traffic capacity and including foundations for an airport rail link.

Transport Agency northern state highways managers Tommy Parker is pleased an early end to the project is in sight, even though the new bridge still has to be paved for traffic and have barriers and other fixtures installed.

These include a new pipeline for Watercare, which will require more night closures of Onehunga Harbour Rd.

The agency has meanwhile decided to allow the public to walk on the duplicate bridge on Sunday, July 25, before three of its four lanes are opened to traffic soon afterwards.

"This will be a great opportunity for the community to spend the day walking on the bridge and learning about the project, and for us to thank the community for their support," Mr Parker said.

Local traffic heading from Onehunga and Walmsley Rd in Mangere will be able to use an "auxiliary" lane on the new structure from early August, and some northbound vehicles may also be allowed on it temporarily while the existing bridge is resurfaced and its median barrier removed.

The project, which began early in 2008, has also included doubling the width of the harbour crossing's motorway approaches between Walmsley Rd and Queenstown Rd in Hillsborough - a distance of about 4km - to carry three lanes of general traffic and a bus priority lane in each direction.

It is expected to be completed seven months ahead of schedule.

The new harbour bridge has been erected on seven piers, and contains about 15,000 cubic metres of concrete.

Three smaller replacement bridges over the motorway have been completed - two for pedestrians and cyclists and a lengthened traffic link carrying Rimu Rd between Mangere Bridge and Favona.

A new walking and cycling bridge is being built over Onehunga Harbour Rd, parallel to the motorway.