Extra lane to speed travel out of capital

Wellington's urban motorway is about to get bigger.

A fourth northbound lane is set to be added to a three-kilometre stretch of the motorway between Aotea Quay and Ngauranga this year as part of a $50 million project announced by the New Zealand Transport Agency yesterday.

Electronic displays will be placed along the roadside to create what the agency has labelled "New Zealand's first fully-managed motorway" where the speed limit will change to reflect traffic conditions along its entire length.

Three emergency stopping bays are also planned.

Wellington highways manager Rod James said the extra lane and stopping bays would be fashioned out of the existing shoulder space.

"We don't have to build a whole new road to make things work better at this location."

The project would loosen up evening rush-hour congestion heading north and take traffic off Hutt Rd, freeing up space for faster, more reliable bus journeys out of Wellington, he said.

"It's another step towards creating a fully integrated, multi-modal transport network for the Wellington region."

Once the project is complete, staff at the Wellington Traffic Operations Centre in Johnsonville will monitor traffic flows and adjust the speed limit to suit.

The theory is that everyone will get to their destination faster if traffic is slowed to ensure it keeps moving, rather than having cars speed toward the end of the motorway and clog it up.

"It's a technique used successfully on high-volume roads around the world, and if drivers follow the lane control and speed limit signs, everyone will get to their destination faster," James said.

If previous upgrades to the motorway are anything to go by then motorists will enjoy noticeable time savings.

Improvements made to the Ngauranga Gorge interchange further north between 2011 and 2013 cut peak-time travel by up to 2.5 minutes in some areas, James said.

Tawa commuter Trish Merz estimated her drive home from the city typically took about 30 minutes. The motorway was definitely a bottleneck, only freeing up after the gorge, she said.

"If there's any sort of accident it backs everything up, sometimes, in really bad situations, for almost an hour."

Although the fourth lane was good news and would be likely to improve the commute, it was the drive south into the city that needed attention, she said.

CentrePort chief executive Blair O'Keefe said the upgrade was important for freight traffic because Aotea Quay was the main road in and out of the port, used by hundreds of thousands of trucks a year.

Road Transport Forum chief executive Ken Shirley, whose organisation represents 80 per cent of the road freight industry, said those trucks needed more room to move. "It's always been recognised [that stretch] is one of the real choke points."

Automobile Association Wellington chairman Michael Gross said the AA was supportive of better linkages from the north into the city.

"This will be an integral part of that. It is good to see it is going to move forward rapidly."

James said the first stages of work would begin in the next couple of months but will be mainly off the highway. Construction will begin in earnest later in the year.

"While this construction work will have a short-term impact on people's journeys, the end result will be well worth it."

The agency's intention is to eventually add a fourth southbound as well, but that was still a "medium-to-long term" project.

What is the Aotea Quay to Ngauranga Project?

A $50 million upgrade of Wellington's urban motorway between the Aotea Quay on- and off-ramps and Ngauranga Gorge. This stretch of motorway is about 3 kilometres long.

It is one of a number of projects that will connect to form a four-lane, 110km-long expressway between Wellington Airport and Levin, known as the Wellington Northern Corridor.

The $2.6 billion package of new roads and improvements was announced by the Government in 2009. The Kapiti Expressway, Transmission Gully and the Basin Reserve flyover are other components.

The Dominion Post