Ask Phoebe: Law clear on when it's murky enough to use the fog lights

Trucks' engine braking is driving one reader up the wall. Photo / APN

Fog lights are increasingly being used at night even when there is good visibility, particularly by SUVs, taxis and boy racers. Is this legal? David Danning, Auckland.

No. The police website says fog lamps should be used only when visibility is severely reduced - for example, in snow or fog. It is against the law to use fog lamps in clear conditions (day or night) as they can dazzle other road users.

There are legal limits on how many extra lights can be fitted on a vehicle and where they are mounted, as well as restrictions on cosmetic lighting. The law says lights must not dazzle, confuse or distract other road users, and sets out how and when you can use some types of vehicle lights.

If you don't get your lights right, not only could your vehicle fail its warrant of fitness, but you could be in for a hefty fine. You can get more information from the Transport Agency website at nzta.govt.nz

Is there a bylaw preventing trucks using their engine brakes along The Strand in Parnell or in any built up area for that matter? I know that this road is the main route for container trucks from the port to the motorway but The Strand is over 50 per cent residential and contains several apartment blocks and townhouse complexes. Where I live opposite the Saatchi & Saatchi building there is a tight corner and we are subjected to noisy engine braking all day and night - sometimes at 2am or 3am. I also know that the police CVIU (commercial vehicle investigation unit) stops trucks along this road for inspection but doesn't seem to be enforcing any engine braking restrictions. Jack Adamson, Parnell.

First, a little background, which I hope I've got right. Compression release engine brakes, also known as Jacobs brakes or "jake brakes", are the noisiest type of brakes. They are fitted mainly on big American engines such as Detroit, Cummins, Caterpillar and Mack. The system modifies engine valve operation to use engine compression to slow the vehicle.

Other large trucks, mainly continental and Japanese models, use exhaust brakes, which are quieter but less efficient.

The Auckland Council has no controls to prohibit engine braking across the city. But a recent change to the transport bylaws allows the council to introduce such a ban should it deem it necessary.

Such a ban would apply on any road where the permanent speed limit does not exceed 70km/h.

Because of this, and as long as vehicles comply with existing bylaws and their vehicles are within the manufacturers' specifications, the police can do nothing about the noise, as there is nothing to enforce.

The council has been working closely with the freight industry to discourage the use of engine brakes.

Engine braking is essentially a safety feature for heavy vehicles, as a supplementary system to the use of gearing, foot and hand brakes. And I guess we'd all prefer it if a 40-tonne truck has a decent chance of stopping.

* An amendment to Tuesday's column: Signs on Ireland Rd and Waipuna Rd apply to Transpower's work to upgrade its grid, in association with the Ameti project.