The Transport Agency hopes to start the project in the New Year and complete it in early 2017.
It should be ready at about the same time as the $1.4 billion Waterview connection starts giving drivers faster trips to the airport from downtown Auckland via the Northwestern and Southwestern Motorways.
The agency last night disclosed a plan to dig a trench to carry airport traffic under busy Kirkbride Rd in Mangere, and to provide slip lanes to turn the dangerous intersection with George Bolt Memorial Drive into a full motorway interchange.
That will do away with traffic queuing at lights there, improving the reliability of trip times to and from the airport and reducing risks of rear-end crashes.
There have been four fatal crashes between the Southwestern Motorway and Kirkbride Rd since 2004, including one on the intersection, and eight which have caused serious injuries.
The project is part of an $815 million package of accelerated Auckland motorway upgrades announced by the Government in May’s Budget, to be part-funded from a $375 million loan.
Daily vehicle trips to and from the airport precinct are predicted to more than double to 140,000 by 2044.
The plan will also close the George Bolt-Montgomerie Rd intersection further south, meaning trucks going to a rapidly growing industrial park will have to turn off at a big roundabout to Landing Drive, closer to the airport.
But Transport Agency highway manager Brett Gliddon said the airport company had built the roundabout for that purpose and to leave an uninterrupted motorway north of that point.
The agency is also considering closing a motorway exit to Bader Drive further north, causing concern to Mangere-Otahuhu Local Board chairwoman Lydia Sosene about the effect on local streets if traffic has to find alternative routes.
She said the community had fought hard for the exit to western Mangere.
Mr Gliddon said a decision about the exit had yet to be made.
The agency wanted to avoid conflicts between traffic accelerating up the future slip lane from Kirkbride Rd, and vehicles cutting across them to the exit.
A possibility was to add an auxiliary lane to what would otherwise be a four-lane motorway running about 4km from Landing Drive to State Highway 20.
Mr Gliddon said disruption to traffic during construction should be minimised by digging the trench slightly west of the existing George Bolt Memorial Drive, while keeping Kirkbride Rd open.
Although there are still no plans to extend the Onehunga railway line to the airport, Mr Gliddon said the motorway would leave room for such a link.
- NZ Herald
- Mathew Dearnaley
- Photo: Dean Purcell