A before- and -after study on green signal countdown device installation

摘要: This paper reports a before-and-after study which evaluated the difference in driver response along an approach of signalized intersection installed with green signal countdown device (GSCD). The main purpose GSCD is to provide drivers timing that would help them make informed stopping/crossing decisions during critical phase-change period. Using special-purpose data logger, four continuous days before-and series at various months’ after-GSCD were collected. findings indicated red-running violations significantly reduced by about 65% 1.5-month but its effectiveness tended dissipate over time as violation numbers had bounced back almost before-GSCD level. dwindling effect curbing longer term generally occurred under high traffic flows. On other hand, vehicles choosing stop onset amber increased 6.2 times installation. increase red-stopping was however sustainable term, albeit relatively small reduction noted. practically effective encouraging actions heavy In effect, one may conclude performance only encourage stopping not red-violations.