Driver Response to the Amber Phase of Traffic Signals

Abstract

Observations of motorist response to the amber phase of traffic signals obtained at five intersections, representing three speed zones, are presented. The data from these observations give an estimate of the probability of stopping for vehicles as a function of their distance from the intersection at the onset of the amber phase of the traffic signal. The results lend no support to a popular hypothesis, i.e., that drivers tend to “take advantage” of a long amber phase by treating it as an extension of the green. The results of the study are compared with other investigations pertaining to amber phase lengths and implications of this work for the design of amber phases is discussed.