ESTIMATION OF TRAVELING TIME BETWEEN RAMPS AND DISCHARGE CONTROL ON EXPRESSWAY

Abstract

In this paper traffic congestion caused especially by traffic accident is analyzed theoretically and traffic control method for congestion on the expressway is considered.The process of spread and vanishment of congestion is first analyzed by using Kinematic Wave Theory. A theoretical method of estimation of traveling time between ramps is also considered. The results show that the congestion does not vanish easily even after the accident is cleared away, and that the traveling time between ramps increases with spread of congestion and soon it becomes that drivers can get to their destination earlier by way of a surface road than by the expressway in case of heavy blockade of lanes or heavy traffic flow.Therefore traffic control procedure should be implemented to prevent the spread of congestion and to shorten the traveling time. A method of recommending discharge from the upper off-ramp is introduced as a control procedure. The beginning time of the recommendation is determined by comparing traveling time on the expressway with that on the alternative surface road.There is a possibility that the congestion continues spreading and reaches the upper off-ramp since not all drivers obey the recommendation. In such a case, a method of enforcing discharge from. the off-ramp is introduced as a control procedure. Simple criteria for changing recommendation of discharge to enforcement and for removing the enforcement of discharge are shown.