PUBLISHED : Sunday, 01 June, 2003, 12:00am
UPDATED : Sunday, 01 June, 2003, 12:00am

Most people realise that cutting the number of vehicles on the road is one obvious measure to reduce greenhouse gases. With the renewed attention on the Kyoto Protocol, fewer understood how a reduction in harmful emissions can also be brought about by improved, steadier traffic flow. This goal can be achieved by lowering traffic speeds.

Exhaust emissions always contain larger amounts of carbon monoxide, hydrocarbons and nitrogen oxides when a vehicle is accelerating or decelerating, or when the engine is idling, than when the vehicle is cruising. Studies carried out after reduced-speed zones were introduced in Germany revealed that car drivers changed gears and used brakes much less often and burned 12 per cent less petrol. One study of the effects of traffic-calming schemes on exhaust emissions revealed reductions of 30 per cent in nitrogen oxide, 20 per cent in carbon monoxide and 10 per cent in hydrocarbons.

Slower speeds means safer, less intimidating roads that encourage more people to walk and cycle, and so bring about reduced pollution.

It is absurd that huge effort and expense goes into the manufacture of very fast cars and, in turn, leads to a massive waste of public revenue in devising and enforcing ways of slowing them down. The government should consider licensing only vehicles designed to run at much lower top speeds, with less powerful acceleration and greater efficiency at lower speeds.

The Bureau for the Environment, Transport and Works should investigate speed-reduction measures and encourage walking and cycling.