Get moving: Flash or dull, plates must be aluminium

Q: I was told recently that the stick-on number plates on my classic car were illegal. They are the same size and colour as standard plates, black letters on a white background. I see many types and colours of standard plates, and wondered what the regulations say. Richard Redstone, Auckland.

A: The Transport (Vehicle Registration and Licensing) Notice 1995 specifies the colours and materials permitted for standard and personalised plates.

In both cases the material must be aluminium. Standard plates can be silver on black or black on reflective white.

Personalised plates can have black, red or blue characters on a white background for the registration number, and can also have subsidiary characters, messages, symbols or slogans approved by the Registrar of Motor Vehicles in any colour, on the frame of the plate.

So, unless your stick-on number plate is aluminium and complies with the above, it is not legal.

Q: Transit has done a significant amount of landfill at the Onewa Rd interchange. In the early stages it used what appeared to be sand, and then covered this with white tags. They were fairly large rectangular tags with coded writing on them. What are they and what purpose do they serve? Greg Thornton, Manurewa.

A: The tags mark the position of wick drains. These are hollow plastic tubes up to 20m long that go down into the ground and act like the wick on a kerosene lamp, with the pressure from the ground forcing the water up.

The water then runs away into the local waterway system, and the ground is compressed. And the coded writing? That would be telling.

Q: What are the parallel blue lines that appear from time to time along the side of the state highways? Paul Brown, Northcote.

A: The Transit person responsible for the maintenance of state highways tried to fob the Herald off with stories of aliens and UFOs, but we are made of more sceptical stuff. The real story is much more prosaic.

The thin blue lines are calibration marks, to enable a high-speed data machine to take accurate readings of the road surface. The machine, which is mounted on a truck, emits an infra-red beam to measure the quality of the road surface with respect to skid resistance, rutting and surface texture.

The blue marks ensure that readings can be taken in the same place each time, so that comparisons can be made and repairs done if necessary.