Warning Efficacy of Active Versus Passive Warnings for Unsignalized Intersection and Mid-Block Pedestrian Cross-Walks

Project summary:

This study evaluated the efficacy of active versus passive warnings at uncontrolled pedestrian crosswalks by comparing how these two warning types influenced the behavior of drivers approaching such crosswalks. In total, the research team completed: 1) a literature review of research findings relevant to cross-walk warning systems; 2) a field study of the relative warning efficacy of active versus passive warnings at selected pedestrian cross-walks; and 3) a design analysis of low-cost alternatives for pedestrian cross-walk warnings. Vehicle-crosswalk interactions were observed at 18 sites with passive, continuously flashing, or pedestrian-activated warnings, yielding 7,305 interactions in which no pedestrians were present and 596 interactions in which pedestrians were present. Vehicle velocities and accelerations were averaged for each interaction. Findings show no significant effect of warning type on overall velocities for either interaction type. With pedestrians present only, for average velocities at successive 5-meter distances from the crosswalk, a downward trend in velocities from 25 meters to 5 meters was observed for passive and active warning sites, but not for pedestrian-activated warning sites. Various lines of evidence point to a number of sources of ambiguity regarding the salience of uncontrolled crosswalk warnings, resulting in behavioral uncertainty by drivers interacting with such warnings. Mixed findings on the effects of warning type in this study point to the need for further analysis of this problem area.