Abstract
Tests have been carried out under controlled conditions in which one car was overtaken by another whilst a third, onco- ling, car was limited the interval available. The start of the interval was signalled by the experimenter and the driver then began to overtake if he thought the interval large enough. The three cars started each run at the same time and travelled at approximately the same speed. Eight drivers each made runs at speeds of 20, 25, 30,40 and 50 mile/h in the same car and the size of the interval was varied, so that in about half the runs overtaking was successfully completed.