Impact of Differences in Driver-Desired Speed on Steady-State Traffic Stream Behavior

Abstract

This paper analyzes steady-state behavior of car-following models within state-of-the-practice commercial traffic simulation software. Car-following models are classified on the basis of their uncongested regime steady-state behavior into two categories. Apart from the INTEGRATION software that uses the Van Aerde car-following model, the research demonstrates that all state-of-the-practice traffic simulation software assumes a constant desired speed that is insensitive to the flow level within the uncongested regime. The paper then quantifies the effect of speed variability, as a common approach to model driver differences with respect to desired speed, on steady-state traffic stream behavior. The paper not only demonstrates that speed variability has a significant impact on the speed at capacity but also develops procedures for calibrating the steady-state relationship while accounting for the effects of speed variability. Finally, the effectiveness and validity of the proposed procedure are demonstrated with an example.