Abstract
The value of a signal shown on the rear of an automobile when the accelerator is released was investigated by measuring (1) the magnitude of decelerations in coasting passenger cars, (2) the ability of drivers to detect coasting of a vehicle they are following, and (3) coasting periods used by a number of drivers on various trips. It was concluded that a coasting signal could not reliably indicate that braking would follow and was largely unnecessary for detection of coasting, but could aid in reducing the development of critical conditions when coasting periods exceed about 5 sec. A signal given only when coasting duration exceeds 5 sec. would not occur frequently and would provide valid information on most occasions.