Unexpected demand brings motorway fix of up to $160m

Both ends of Auckland's western ring route will be widened at a cost of up to $160 million as early as next year. Photo / Paul Estcourt

Both ends of Auckland's western ring route will be widened at a cost of up to $160 million as early as next year, after the Transport Agency admitted underestimating traffic demand.

It said yesterday its board had given approval for sections of the Southern and Northern motorways to be widened to ease congestion and improve travel times.

That follows serious traffic delays where the ring route was joined to the Southern Motorway at Manukau in September in a $220 million project which was meant to provide a seamless link.

Congestion has eased somewhat since the agency restricted flows from the ring route to the main motorway, before installing traffic lights on the connecting ramp last week.

But after complaints from commuters about delays of up to 40 minutes reached Transport Minister Steven Joyce, the agency decided to bring forward the first stage of a previously unfunded plan to widen the Southern Motorway between Manukau and Papakura.

Its board has also decided to avoid similar congestion problems at the top end of the ring route, by widening the Northern Motorway between Constellation Drive and Greville Rd to cope with the extra traffic expected once the $1.75 billion Waterview connection completes the bypass route in 2016.

Transport Agency regional director Stephen Town said that although funding for both projects had yet to be approved, his organisation hoped to start widening the southern end in the middle of next year and the northern section soon after the Rugby World Cup.

His transport planning manager, Neil Cree, told the Auckland Council's transport committee yesterday that the first stage of the Southern Motorway widening project - adding a third southbound lane between Hill Rd in Manurewa and Takanini - was expected to cost $40 million to $80 million.

The project would eventually extend to Papakura before a fourth lane was added to the motorway between the ring route and Hill Rd.

Adding a third northbound lane between Constellation Drive and Greville Rd on the Northern Motorway was likely to cost between $50 million and $80 million.

Mr Cree admitted that the delays at the southern end of the ring route followed the diversion of more traffic than the agency had expected from Roscommon Rd, to join the motorway at Manukau rather than Manurewa.

But he said that since the traffic lights were installed, there had been no traffic build-ups on the Southern beyond Te Irirangi Drive.