On-ramp lights will aid traffic flow, Transit says

Transit NZ is assuring sceptics that the aim of a complex plan to install traffic lights at on-ramps on Auckland's Southern Motorway will help rather than impede traffic flow.

It promises that the $27 million system will be monitored closely once it is rolled out in three months, and that "ramp signals" can always be turned off for periods if queues end up stretching too far back down local roads.

The agency hopes eventually to manage flows along Auckland's entire motorway network with signals at each on-ramp, controlled electronically through the region's traffic management unit next to the harbour bridge, among other measures to prevent gridlock.

Contractors will cut their teeth in October on the southbound only on-ramps from Papakura and Takanini, before adding signals to eight new links to be opened progressively through December and possibly January in the $195 million Central Motorway Junction upgrade.

More electronic information signs will also be installed on gantries above entries to the junction to help to shepherd motorists through it.

The Southern Motorway's 21 other on-ramps will be joined to the signalling system by the end of next year, when preparations should also be well advanced for similar lights along the Northern and Northwestern Motorways.

Transit has awarded a $27 million contract to Transfield Services for all on-ramps and infrastructure between Curran St and Papakura on the Southern Motorway, including electronic traffic sensors embedded in the road surface.

About $21 million more will ultimately be spent on 30 on-ramps to the other two motorways.

Transit travel demand project director Peter McCombs said that the Transfield contract would cover any necessary alterations to Southern Motorway ramps, most of which would be converted to operate with two lanes.

Three uphill ramps carrying heavy freight volumes - from Grafton Rd, Mt Wellington and the nearby Southeastern Highway - will be widened to provide extra priority lanes for trucks and buses.

That will allow them to maintain momentum and not hold up other traffic, although the haulage industry fears drivers may face longer delays on approach roads, tempting them to "rat-run" through the suburbs.

A two-year trial of ramp signals controlling traffic joining the Southwestern Motorway from Rimu Rd and Mahunga Drive south of the Mangere bridge remains controversial, despite its being hailed by Transit as a success.

Roger Baldwin, president of the Mangere Bridge Residents and Ratepayers Association, said it still sometimes took him up to 25 minutes to inch on to the motorway through the town centre, and that Transit had "a fair way to go in getting their system perfect".

But Mr McCombs said the signals had improved overall peak-time speeds on the northbound motorway lanes by about 20 per cent, and boosted traffic flows across the bridge by some 9 per cent.

Told of concern among Manukau City transport officials about the length of time taken by Transit to respond to requests for measures to hasten buses past queues to the Mangere ramp, which are now in place, he said: "We learned from all of those experiences."

"There is a firm undertaking from Transit that this is a project being undertaking to improve traffic flows," he added.

Mr McCombs said a memorandum of understanding with Auckland councils already involved with Transit in running the traffic management unit had been expanded to include an assurance that the new operation would be adjusted to cope with any problems.

Signals at individual locations would even be suspended if necessary, until such difficulties could be "straightened out".

He said the system should not be regarded as a rationing of scarce motorway space.

"Rationing implies a degree of restriction, where actually this system increases throughput - it improves the speed and improves the overall performance," he said.

The plan

* Traffic lights will be placed on every motorway on-ramp in Auckland to control traffic flow.

* Work starts on the Southern Motorway in October and all 21 lights should be installed by the end of next year.

* Traffic lights will then be placed on on-ramps on the Northern and Northwestern Motorways.