Comparison of Analytical and Field-Estimated Lost Times at DDIs

Abstract

Diverging diamond interchanges (DDIs) are one of most successful unconventional type of diamond interchanges in the United States. This paper examines additional lost time due to internal link queue presence in DDIs. First, an analytical approach was developed providing a step-by-step method to predict the additional lost time at the crossover movements. Second, actual field data were collected to validate the analytical approach of comparing additional lost time using the team’s analytically derived approach to that of actual field data. The analytical method was proven to be a valid prediction of the additional lost time at the ramp terminal intersections. In addition, unique signal timing of DDIs is presented, showing efficient interchange operation under heavy traffic condition on arterials.