Ask Phoebe: Signs become clear - if you follow me

Can you tell me what these signs are supposed to tell us? They are everywhere but seem to have no purpose or logic. Peter McGregor, Sandringham.

They are emergency state highway detour signs. If a major incident closes a main highway, these signs will point to a recommended detour. When in operation, a fold-down sign, at the start of the detour several hundred metres in from the state highway, will advise motorists.

The main one in the Auckland area is Woodcocks Rd/West Coast Rd between SH1 and SH16 at Warkworth.

I have noticed a rash of temporary 80km/h speed limit signs on the northbound approach to the harbour bridge. Why are they there, when the permanent 80km/h limit appears to be still in force from the Newmarket Viaduct to the northern end of the bridge? Gary Kendall, Rothesay Bay.

It's all to do with the two major projects in the area, namely the Newmarket Viaduct and the Victoria Park Tunnel.

Parts of the motorway near these projects have been derestricted so that temporary restrictions can be put in place when they're required. For example, the northbound approach to the Harbour Bridge, around St Marys Bay, has been derestricted. Until a 70km/h temporary restriction is required, a temporary 80km/h restriction is in place. Replacing the permanent 80km/h limit, one assumes. I can't quite get my head around the logic of that.

The speed restrictions are in place for safety reasons, because of the distraction provided by the construction work, and narrowing of traffic lanes.

Getting to the Northcote Rd southbound onramp from Taharoto Rd in the mornings must be about the most frustrating Auckland traffic experience. At each light sequence the queue gets from 15 to about 40 seconds to turn left on to the onramp, compared with more than 65 seconds for facing traffic. As a consequence traffic is queued back to the Northcote Rd / Taharoto Rd intersection and beyond from 7am. There is much queue-jumping, anger, poor driving (eg, around the wrong side of traffic islands) and general chaos and it can take 15 or 20 minutes to travel the 750 or so metres down Northcote Rd.

Are there any plans to improve the area's traffic flows? One small action could be to even up the onramp light sequence to give traffic from the east an extra 20 or 30 seconds. Martin Pyke, North Shore.

It shall be done. The Transport Agency, in conjunction with North Shore City Council, will be making some changes over the next few days at the Northcote/Taharoto lights to increase the phasing for left-turning motorists on to the southbound onramp. See, they do listen.