$14m to revamp Greenlane roundabout

The Greenlane roundabout, one of the busiest interchanges in Auckland, is about to have major work to improve traffic flows.

The roundabout straddles the Southern Motorway, and is the main east-west arterial route across Auckland's inner city suburbs from Remuera to St Lukes.

Under the Transit NZ-Auckland City $14 million project, vehicles heading for the motorway will have new slip lanes to on-ramps which will allow much of this traffic to avoid the 42-year-old roundabout (click on 'More Pictures' link above to see diagram).

Big improvements are also planned on the Green Lane East Rd, Green Lane West Road and Great South Road - more lane space, modified intersections, and bus lanes in Great South Road. Cycleways, footpaths and landscaping are part of the mix.

The roundabout is also to get another lane on its southern side, which will allow two lanes of east-west traffic to flow through towards Green Lane West Rd without tangling with traffic in the right lane heading from Remuera to the northbound on-ramp.

With the addition of the new slip lanes there will be two on-ramps going north and two south. The two streams in each will be merged into one before traffic reaches the motorway proper.

For the first time on the Southern Motorway that will be achieved (when needed in rush hours) by monitored traffic signals on the ramps. The system, called ramp metering, was first tested on Rimu Rd in Mangere Bridge.

Transit NZ says it is part of essential controls to keep traffic flowing. The aim is speeds around 70km/h, said to allow maximum vehicle flows along the heavily used system.

Work on the roundabout is expected to be over in 10 months, and on surrounding roads in 20 months.