Get moving: Traffic island moves for heavily loaded big trucks

Q: A traffic island has appeared and disappeared over and over again (well, at least three times, maybe five) in Mt Eden Rd between Enfield St and Boston Rd. When it's there, it seems to be a pedestrian refuge. Why the now-you-see-it, now-you-don't trick? Nick Barling, Laingholm.

A: Mt Eden Rd is the designated route for overweight and extra-wide or long vehicles travelling through the city. When one of these large trucks is scheduled, the islands have to be removed so the trucks can manoeuvre. Because there is often quite a time gap between these events, the council puts the islands back in the interim. The good news is that no further large loads have been booked for the near future.

Q: Silly question perhaps, but can you please tell us what the white markers are at frequent intervals all over the area in the Keith Hay Park-Somerset Rd section of the Southwestern Motorway extension road works? They look rather strange. Bette Swan, Auckland.

A: The white markers are hollow plastic tubes called wick drains, and they have been installed to drain water from the ground. The earth round Keith Hay Park needs to be compressed to enable construction and draining the water off allows that. The 20m wick drains act like the wick in a kerosene lamp, and when heavy material such as clay is laid down on the area, the pressure forces the water out. The water then runs off on a metal drainage blanket into the local waterway system.

Q: At the intersection of Taharoto and Northcote Roads there are two lanes for traffic turning right from Taharoto into Northcote, two lanes for traffic turning right from Northcote into Taharoto, but only one lane turning left from Taharoto into Northcote. There are extensive roadworks in this area, so why have the changes not included two left-turning lanes, if necessary moving the pedestrian island? Kay Miller, Takapuna.

A: North Shore City Council says that the need for an extra left-turning lane here will decrease next year with the opening of the Esmonde Rd interchange. The new interchange will allow traffic from Devonport and Takapuna to connect with the Northern Motorway as well as with Northcote and Glenfield, via Akoranga Drive.

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Contact Phoebe Falconer at Get Moving, Editorial department, NZ Herald, PO Box 32, Auckland. Fax (09) 373-6421. Include name and address.