Reducing peak time congestion, and improving travel time reliability and safety on the busiest section of Wellington’s urban motorway are the main objectives of the Transport Agency’s Ngauranga to Aotea Quay upgrade.
The upgrade will provide an extra (fourth) northbound lane from the Aotea on-ramp to Ngauranga and will result in New Zealand’s first ever smart motorway.
Building the smart motorway
The Transport Agency is using every possible innovation to find space for the fourth northbound lane. For example, a small grass verge just north of the Aotea on-ramp, as well as an unused bridge stub at Kaiwharawhara, will be put to use as part of the new lane. Also, replacing the existing gravel-filled median safety barrier with a narrower and safer concrete extruded barrier will provide an extra 3 to 4 metres of valuable road width.
Other construction elements of the project include:
What exactly is a smart motorway?
A smart motorway is one fitted with a network of detection equipment (radars, loops and cameras) and electronic signs, which automatically adjust the speed limit to reduce congestion and increase the number of vehicles getting through a section. They’re used effectively around the world as transport agencies seek to improve people’s journeys while getting the most out of existing road corridors.
There are three main parts of a smart motorway:
When all the parts come together, the stop/start nature of congestion is reduced, traffic moves more smoothly, more vehicles get through a section of road and everyone gets where they’re going sooner and more safely.
How the ‘smarts’ work
Smart motorways reduce congestion by carefully controlling the flow of vehicles. The most critical time the system can influence the severity of congestion is as the traffic volume begins to build (i.e. before the road becomes congested). Detectors under the road and radars count the number of vehicles in each lane, as well as the speed they’re travelling. The smart system automatically adjusts the speed limit to pace the traffic and reduce the number of vehicles rushing to join the back of the queue.
Wellington’s smart motorway is due to be operational in April 2016. You can keep up to date with progress at www.nzta.govt.nz/smartmotorway(external link).