The research summarized in this paper investigated the need for changes in the passing sight distance (PSD) criteria used for design of two-lane highways and for marking of passing and no-passing zones on two-lane highways. PSD models from the AASHTO Green Book and the MUTCD were first comparedwith models developed in previous research to determine the most accuraterepresentation of the passing maneuver. It was determined that two models, developed by Glennon and Hassan et al., warranted further consideration.Field studies were then conducted in Missouri and Pennsylvania and recentfield data from a study in Texas were also evaluated to validate the assumptions made in the passing models. It was determined that based on current driver behaviors no change in the PSD criteria used for marking passing and no-passing zones was needed. The research found that two-lane highwayscan be safely designed with any set of PSD criteria equal to or greater than the PSD criteria used in marking passing and no-passing zones, insteadof the longer PSD values currently used in design. The use of the currentPSD marking criteria in design will provide desirable consistency betweenPSD design and marking practices.
Samenvatting