Spacing of Intersections in Hierarchical Road Networks with Inward, Outward, and Through Traffic

Abstract

This paper develops a continuous network model for examining the spacing of intersections that connect different levels of roads in a hierarchical network. The model extends a previous model to incorporate inward, outward, and through traffic, thus providing a more appropriate framework for analyzing the intersection spacing. An analytical expression for the total travel time is obtained for a grid road network with two road types. The travel time is dened as the sum of the free travel time and the delay at intersections. The analytical expression leads to a clear understanding of the tradeoff between the accessibility to higher level roads and the delay at intersections. The optimal pattern of intersections that minimizes the total travel time is then obtained. The result shows how the road length, the intersection delay, the travel speed, and the traffic composition affect the optimal intersection pattern.