Abstract
Improved average operational speed, regularity in service and circulation time of the buses have been obtained in Paris and Marseille where road lanes have been reserved for buses and other services such as police and the fire-brigade. A method is described of the setting up of a model to measure and evaluate the gains and losses in travel time. It is shown that in some cases (e.g. peak hours) private traffic may even benefit by it, as expressed in time gained. Some tentative guidelines (e.g. roads at least 3 lanes wide) are proposed for the practical application. The whole organisation of the bus network should be reviewed and reconsidered at the same time.