Ask Phoebe: Ramp-control signals switched on only when they can help traffic flow

Q. On several recent workdays, the traffic buildup on the Northwestern Motorway at about the time I enter from the Royal Rd onramp, at 7.45am, has meant a delay of five to 10 minutes. I understood the ramp control signals came on if traffic speed slows and traffic volume is significant. Some mornings the ramp signals have been on but have made no apparent difference to the traffic entering from the onramp or on the motorway which is moving slowly and in stop-start fashion. Some mornings the signals have been off even though there is still a substantial volume of slow traffic. How is this monitored, and when do the signals go on and off? Michael Hamilton, West Harbour.

A. The NZ Transport Agency says the ramp signals operate when they can make a positive difference to the traffic flows on the motorway network. At other times they are turned off. On most mornings, says the NZTA, the Royal Rd ramp signals usually turn on after 6.40am and operate until motorway congestion extending back from Lincoln Rd begins to block incoming traffic at Royal Rd, usually after 7.30am. The signals then remain off until congestion begins to clear, when they switch on again until the traffic begins to flow more freely. The Royal Rd ramp signals are a part of a wider system trying to make a positive contribution to traffic flows on the Northwestern Motorway.

Q. Nearly six years ago, I wrote to Transit NZ [now the NZ Transport Agency] pointing out the safety risk created by the 2m-high steel grill barrier separating the western lane of the Northwestern Motorway from the cycle track at the Te Atatu turnoff.

The barrier on the turnoff bend reduces vision to only 20-30m, forcing drivers in the left-hand lane leading to the turnoff to brake suddenly when they find themselves confronted by a queue stretching back from the lights at Te Atatu Rd. People travelling legally at 80-100km/h have next to no time to respond, and there is no warning sign. This is not such a problem for local people familiar with the "trap", but it could be lethal for the unwary, especially on wet winter days. In 2004, Transit NZ replied, agreeing there was a safety risk and explaining it was working on a solution. Six years on, there has been no change and the accidents keep happening. When are they going to do something about it? Bruce Morris, Mt Albert.

A. The Transport Agency plans to deal with this issue as part of general improvements to the Northwestern Motorway. The project includes widening the Whau River bridge east of the Te Atatu interchange, as well as lengthening the westbound offramp at Te Atatu, which should improve visibility for drivers heading west on the motorway. Progress on the project is at the stage of finalising land purchases and preparing to lodge consent applications with local authorities before calling for tenders for the work.