Analysis of distance headway

摘要

By means of the relationship between speed and distance headway, this paper attempts to directly determine the road capacity based on a new concept. At first it makes a comprehensive analysis of distance headway, including safe distance headway and desired one. The former is decided by the demand for the degree of safety, and the latter depends on the motorists' behavior, i.e. the model of traffic flow. Both of them are functions of speed. According to the characteristics of their curves, we can find a crossing point that is the capacity of a road segment. This capacity represents the maximum flow rate meeting the minimum safety requirement.