Until recently no German specification existed for the use of grade separated junctions at rural two-lane highways. In the research presented here traffic safety and traffic flow of two-lane rural highways with interchanges were analysed. With the results conditions could be defines under which the use of interchanges is not only efficient but also necessary. An empirical research program was also developed. Accidents for the whole road were analysed in a microscopic and a macroscopic way. Measurements of speeds at spots were made. Conflicts in merging areas were measured at several locations and different times in order to assure data from merging areas of different length and with variations in the traffic flow. In a multi critical analysis all layout aspects were considered. Furthermore, economic and environmental aspects were considered. Finally, application recommendations were formulated dependent on the traffic volume, the required travel speed and on the distance between junctions. (A)
Abstract