Theoretical issues related to two phenomena observed in a study of four freeway bottlenecks in san diego are addressed. It was observed that flow immediately downstream of the bottlenecks decreased bya small amount when it broke down and that flow breakdown appeared to be triggered by speed instability. Most of the flow decrease could be attributed to the increase in vehicle passage time that occurs when speeds decrease, and most of the san diego data are compatible with the linear car-following model of chandler et al. As extended by bexelius, although a number of questions about the validity and applicability of this model remain. This paper appears in transportation research record no. 1320, Freeway operations, highway capacity, and traffic flow 1991.
Abstract