EFFECT OF SIGNAL HEAD LOCATION ON STOP-LINE ENCROACHMENT

A common concern among traffic police officials in Saudi Arabia is the fact that drivers encroach on the area beyond the stop-line while wai ting on red at signalized approaches. In a measure to prevent this fro m occurring, officials have removed the far-side signal head, leaving only the one on the near-side, arguing that drivers will be able to se e the signal only if they stop upstream of the near-side signal head w hile waiting on red. This study tested this argument by comparing stop -fine encroachments at approaches with near-side only signal heads wit h those having near and far-side configurations in Dammam, a city on S audi Arabia's east coast. This study concluded that encroachments are significantly higher in the first case than in the second, suggesting that, for the study approaches, this measure has exacerbated, rather t han helped, the situation in the study sample. It seems that the exist ence of the far-side signal head enforces the law in that it deters dr ivers from encroaching the area beyond the stop-line. Further study of this phenomena is recommended.