Ask Phoebe: Police can't crack down on noisy engine brakes

Why do there appear to be no restrictions against engine compression braking by heavy commercial vehicles in downtown Auckland, in particular those accessing the port via The Strand in Parnell and Beach Rd? Both these areas have council-approved intensive residential areas. If there are controls or policies, why are they not enforced?
Mike Reynolds, Auckland.

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. These are quieter but less efficient and use engine-exhaust back pressure as the braking method.

Auckland City Council has never had any controls in place to prohibit the use of engine braking across the city. 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. It does not propose to introduce any changes to the bylaw, as it has no strong evidence that heavy motor vehicle braking is the sole contributor to excessive noise from such vehicles. Regular heavy traffic noise, from high volumes and road/tyre interface, all add to the cacophony.

Engine braking is essentially a safety feature for heavy vehicles, as a supplementary system to the use of gearing, foot and hand brakes.

Tony Friedlander, chief executive officer of the Road Transport Forum, says because of this safety issue, the forum does not encourage local councils to ban the use of engine brakes, although a quick Google search uncovered several councils that do.

These councils put up signs asking trucks not to use engine brakes in their area, and the forum encourages its members to heed the signs.

The slightly better news is that new-generation engine brakes bring with them reduced brake noise. Mr Friedlander tells of a motel owner at the top of the Ngauranga Gorge heading into Wellington, just where truck drivers test their brakes before heading down the hill. This has irritated the motelier for years, but he now notes a greatly reduced noise level.

I guess we'd all rather know that a 40-tonne truck has a decent chance of stopping than the alternative.

I would like to know when the relevant authorities are going to seriously police the bus lanes on the harbour bridge, particularly on the southern side. Recently, in the time it took me to travel from the Shelly Beach offramp 150m around the corner, 13 cars passed me in the bus lane. Most of these cars try to manoeuvre their way across lanes to get into the Southern Motorway lanes, thereby holding up traffic in the Fanshawe St lanes. I notice that Auckland City Council uses a video camera to record cars in bus lanes along Fanshawe St. Why can't the motorway authorities do the same?
Paul Estcourt, Torbay.

The New Zealand Transport Agency has an ongoing issue with unauthorised use of bus lanes. If one driver uses the bus lane illegally and gets away with it, then it just encourages others to do the same.

It's not safe to enforce a bus lane on a motorway using the same method as local authorities do (i.e. someone standing on the side of the road with a camera). Instead, the Transport Agency will enlist extra help from the police to enforce the law.