Calculations have been made for the policy regarding speed limits for cars and lorries to get the lowest emissions and fuel consumption. Research has been done on motorways with speed limits from 50-130 km/h for cars and 50-100 km/h for lorries, highways with speed limits from 30-80 km/h, and roads in urban areas with speed limits from 10-50 km/h. Emissions from the polluting components such as nitrogen oxide, hydrocarbons, carbon dioxide and sulphur dioxide, are calculated. It is shown that a reduction of the emissions and fuel consumption can be achieved by decreasing the speed limits for cars and lorries on motorways. Optimal speeds should be 70 km/h for cars and 60 km/h for lorries. lorries. Besides the modification of the speed limits improvements can be achieved by a better traffic flow in particular in urban areas. Driving behaviour has also its influence on emissions. It is obvious that "quiet" driving behaviour, dependent of the situation and the use of an exhaust catalyser, is 35-85 percent lower than "wild" driving.
Abstract