Samenvatting
This paper considers the effect on the operating costs of lorries and buses due to the increased wind resistance encountered at motorway speeds. It is argued that the installation of more powerful engines to overcome drag and maintain established motorway speed leads to an increase in the load cost per km. Speeds of 70 and 90 km/h are considered, and the calculations show that for fully laden transport the specific cost increases considerably for low values of frontal area, and diminishes much less markedly as this value increases. With reduced loads, and the potential transport capacity unchanged, a greater frontal area can considerably increase the cost of transport.