Work begins on $18m motorway lane

Work is starting this week on a new traffic lane costing $18 million for one of the busiest stretches of Auckland's Southern Motorway, between Newmarket and Greenlane.

Transport Agency contractors hope for better weather for the next three nights to allow roadworks requiring the temporary closure of about 2.4km of the motorway's southbound carriageway, including over the 690m Newmarket Viaduct.

As well as needing to erect more safety barriers for its $215 million viaduct replacement project, the agency wants to change lane markings on the 1.7km stretch between Market Rd and the Greenlane interchange.

That is where a fourth lane is to be built by early 2011 as an associated project, to be tied into a new southbound viaduct in time for the Rugby World Cup.

Agency regional director Wayne McDonald said the extra "auxiliary" lane combined with the new viaduct would help to relieve congestion bottlenecks on New Zealand's busiest section of motorway, from Spaghetti Junction to Greenlane.

Although southbound traffic volumes usually ease past Gillies Ave, the stretch between Market Rd and Greenlane still carried a daily average of about 165,000 vehicles last year, according to agency surveys.

But drivers will have to put up with a reduced speed limit of 70km/h from tonight, as a temporary measure identical to what has already been introduced to the viaduct's southbound carriageway.

Lane widths will also be cut from 3.4m to 3.1m to reduce hazards while workers widen the motorway within its existing designation, using the harbour bridge's former moveable median barrier to protect themselves from the traffic.

Concrete noise walls will beerected 3m high, outside thenew lane, to provide visual andsound barriers for local residents.

Although Transport Minister Steven Joyce yesterday formally kicked off the project, rain prevented work from starting last night.

Tonight's scheduled southbound motorway closure, between 11pm and 5am, remains conditional on clearer weather.

Although the motorway's northbound carriageway will remain three lanes wide, because of limited space available for traffic travelling through Spaghetti Junction, a replacement northbound viaduct will be built by early 2012, with an improved seismic rating deemed capable of protecting it from a once-in-2500-year earthquake.