Interchange Critical Movement Analysis for Planning and Preliminary Design Applications

Abstract

A procedure that can be used to compare a variety of common interchange types or make decisions about their design is described. The technique is based on the critical movement analysis approach traditionally used for signalized intersection analysis. This approach defines the rules for quantifying the sum of critical flow ratios for various interchange types. The concept of interchange delay is defined, and an equation for quantifying it is described. Simulation data are used to calibrate a series of models that relate the sum of critical flow ratio to interchange delay. A procedure that describes how these models can be used to obtain a quick estimate of the delay associated with a particular interchange type, given specific volume levels, lane assignments, and ramp separation distances, is documented.