טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSami Edry
SubjectRed-with-Yellow Signal at Traffic Lights: Aspects of Safety
and Efficiency
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Mahalel David
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

In Israel, as well as in several other countries in the world, the traffic light includes a red-with-yellow phase. This signal is designed to inform the change to green light, but holds the same prohibition as the red light. Its main purpose is to increase the saturation flow to the intersection by reducing the start-up lost time . This method is not practiced in most countries around the world (USA, Australia, etc). In countries where the red-with-yellow signal exists, the appearance duration varies from one to two seconds. Some countries have reduced or omitted this signal, and some are considering reducing or totally omitting it. According to the Israeli guidelines, the red-with-yellow signal is fixed at two seconds and is an integral part of the inter green time interval, which is designed to insure the evacuation of the intersection at the end of the previous phase and before the beginning of the proceeding phase. One can say that the degree of reduction in right-angle road accidents, at signalized intersections, significantly depends on the calculation of inter green time interval. In Israel, Such kind of accidents is a significant proportion of all accidents at signalized intersections. Observations have shown that drivers often enter the intersection before the end of the inter green time interval, during the red-with-yellow signal. This study aims to examine the utilization of the red-with-yellow signal by the driver, and whether there is a difference between passenger cars and Motorcycles. In addition, the study examines the degree of effectiveness of red-with-yellow signal operation in reducing start-up lost time. The results indicate that a significant percentage of drivers taking advantage of the red-with-yellow phase. Most of the passenger car drivers begin their movement within the appearance of the red-with-yellow light. A smaller proportion also crosses the stop line during the red-with-yellow signal, ie, within the period of inter green time interval. Motorcycle riders cross the stop line during red light or at the very beginning of the red-with-yellow signal. In addition, it seems that the start-up lost time is very short (approximately 0.5 seconds) and in fact does not exist. The study's conclusion is that utilizing of the red-with-yellow by the drivers, makes it, in fact, a part of the effective green. Therefore, a removal of the yellow signal or at least a reduction of one second in its duration should be performed.