Effectiveness of Speed Limit Pavement Markings at Transition Zones Along Expressways

Transition zones are usually equipped with speed limit signs only. Drivers usually miss the speed limit information provided through the roadside signs and travel faster than the posted speed limit. This driving simulator study evaluated the effect of speed limit pavement markings on driving behavior. Speed limit encircled markings were placed on the road surface at transition from 120 to 100 kph. The markings were based on forced perspective illusion where size of the markings was gradually increasing in the traveling direction. Eighty-one drivers with a valid Qatari driving license participated in the study. The study results showed that the speed limit markings motivated drivers to reduce their traveling speed while entering the lower speed zone. Compared to the untreated scenario, in the scenario with speed limit markings, drivers' mean traveling speed was lower than the speed limit (i.e. 100 kph) after entering the transition zone. Furthermore, speed limit markings increased drivers' attention, making them realize that they are entering the lower speed zone. Based on the results from this study, speed limit markings are recommended for policy makers as a low-cost speed calming measure for areas where speed limits significantly drop such as transition zones on highways or school zones.