Motorway cleared for tunnel wall

Lane changes for southbound traffic on the Southern Motorway as they come off the Victoria Market flyover. Photo / Brett Phibbs

A launch pad is being cleared on one of the busiest parts of Auckland's motorway network for equipment to start building large retaining walls for the Victoria Park tunnel.

Motorway lanes between the Victoria Park viaduct and Wellington St have been modified and narrowed to make room for a 60-tonne crane which is scheduled to arrive tonight to sink piles for a pair of 300m-plus retaining walls leading to the tunnel's northern portal.

A drilling rig is expected to be installed tomorrow night.

The first wall will be built between the north and southbound motorway carriageways.

Once this is done, the northbound lanes will be shifted so the second wall can be built on their western side.

Both southbound lanes are being closed at nights this week and next for the removal of a large concrete barrier, the final section of which is posing considerable difficulties for the contracting alliance which is building the $406 million tunnel project for the Transport Agency.

That means traffic has to follow a detour route between the motorway's Fanshawe St off-ramp and the Hobson St on-ramp.

Northbound motorway traffic will also be restricted to one lane between 11pm and 5am tonight, and on up to five more nights from Sunday.

Although traffic lanes are being kept open in both directions by day, rubber-necking by drivers and a reduced speed limit of 70km/h through the work site have been causing considerable congestion at times.

That has led to a plea from the Transport Agency's northern highways manager, Tommy Parker, for drivers to exercise care and patience while waiting for the completion of a project which will provide three more traffic lanes through what has long been Auckland's worst motorway bottleneck, carrying about 165,000 vehicles a day.

"It is inevitable there will be some delays and the Transport Agency apologises for that," he said.

"But at the end of the day the pain will be worth the gains to be made when the project is finished."

Although the contractors began removing the motorway median barrier last month, they were forced to a halt when some sections were found to have a solid concrete base, making their removal by conventional techniques too noisy for nearby residents to bear.

That meant reaching a quieter compromise, using a wire saw to cut the concrete into manageable blocks, an operation which began on Sunday night.

Both retaining walls will be built from the surface down, before the earth between them is scooped away to provide the tunnel's northbound entrance.

The eastern wall will be about 10m high, to support the southbound traffic lanes on their existing level, although three northbound lanes will eventually run through the tunnel.

Construction of the 440m tunnel, which is expected to take just over a year to dig, will start after Victoria St West is temporarily looped into Victoria Park at the end of this month to make way for the excavators.

The bottom end of Franklin Rd will also be looped into Union St before joining Victoria St West, and the.

DISRUPTION

* Motorway lanes between Victoria Park viaduct and Wellington St have been modified.
* Both southbound lanes are being closed at nights this week and next to allow removal of a large concrete barrier.
* Traffic will follow a detour route between the motorway's Fanshawe St off-ramp and the Hobson St on-ramp.
* Northbound motorway traffic will be restricted to one lane between 11pm and 5am tonight, and on up to five more nights from Sunday.