A review of motorway signals

Research carried out on motorway signals is reviewed. Attitude and driver response studies show that the recommended speed limits displayed on the current signals are not well respected. Two major studies of improvements to the signals have been carried out and a third is underway. From these it is concluded that: (1) drivers would respond better to signals if, along with the speed limit, information were added telling drivers why the signals are in use; (2) signals should be operated automatically whenever possible; and (3) signals should be sited at a closer spacing of about 1 km. (A)