Traffic performance on two-lane, two-way highways : examination of new analytical approaches

Abstract

This project presents research on estimating traffic performance on two-lane, twoway highways. The main research objective is to examine two new approaches / methodologies in estimating the Percent-Time-Spent-Following (PTSF), a major indicator of performance on two-lane highways. The first new approach, named the weighted-average approach, is based on the weighted average of speeds for various vehicle types within the traffic stream. The second new approach, named the probabilistic approach, is concerned with using probabilities in estimating the PTSF. The need for this investigation has arisen from the concern that the current analytical procedures, namely the Highway Capacity Manual (HCM) 2000, provide erroneous results as suggested by previous research. The project reviews recent literature on the HCM procedures and evaluates their effectiveness using both theoretical and empirical analyses. Furthermore, the two new approaches were evaluated using empirical data from three study sites located throughout Montana's two-lane, two-way highway system.