EVALUATION OF AN ALTERNATIVE TRAFFIC LIGHT CHANGE ANTICIPATION SYSTEM

A driving simulator was used to study the efficacy of an alternative s ignal phasing program. The new Traffic Light Change Anticipation Syste m (TLCAS) utilizes a flashing amber in conjunction with a solid green indication to warn drivers of the impending onset of the solid amber i ndication. This new program was expected to provide drivers with addit ional information with which to make safe stopping or crossing decisio ns, and reduce behavior associated with increased accident rates at si gnalized intersections. Additionally, a new measure of first response variability was introduced to evaluate the effect of the new program o n driver behavior. The results indicated that the new system has the a bility to reduce the number of red light violations. Of the 1148 targe t intersections, 43 violations were recorded for the regular program c ompared to 9 for the TLCAS program. The severity of decelerations was also impacted. The regular program displayed average maximum decelerat ions of 3.1 m/sec(2) compared to 2.5 m/sec(2) for the TLCAS program. H owever, the TLCAS program showed an increased variability in first res ponse five times larger than the regular program. This finding, in con junction with traditional measures, indicates that the new system perf orms comparably to an increased amber duration by increasing the poten tial for conflicting decisions between successive drivers approaching an intersection. Altogether, the results suggest that this alternative signal phasing program would not improve intersection safety. The fin dings also suggest that further study of the longitudinal behavior aft er the introduction of a TLCAS program may be warranted. Specifically, future studies should examine whether subjects engage in appropriate adaptive changes when confronted with a solid amber period warning aft er becoming familiar with the TLCAS. (C) 1997 Elsevier Science Ltd.