Abstract
The present study deals with the question of whether or not drivers are consistent in their choise of speed and acceleration from the data of test to that retest ten days or ten weeks later. A new technique has been devided for this purpose. It was found that some drivers show a marked consistency in ther choise of speed and acceleration, and that those who are most consistent in any one road situation, are likely to be consistence in other situations whitin the limits of the experiment.