Prior to the widespread implementation of ABS brake technology in light vehicles, driver training often included instruction to “pump the brakes” to avoid locking the wheels. Many driver education programs now recommend maintaining high brake pedal force and relying on ABS. It is sometimes asserted that drivers desiring to stop a vehicle quickly still “pump the brakes”. Investigators sought to understand whether drivers desiring to decelerate quickly pump the brakes, especially in a way that may deplete the vacuum stored in a vehicle's brake booster if so equipped, or whether they apply the brakes in a manner corresponding to their desired deceleration.
The National Highway Traffic Safety Administration (NHTSA) conducted a testing program to examine driver braking behavior in crash avoidance maneuvers. The data for those 245 test runs were reanalyzed, assessing patterns of brake pedal force application to determine whether pedal force variation was sufficient in magnitude and duration to reflect driver intent. Analysis included a survey of peak brake force applied and the number of significant brake force application peaks during the avoidance maneuver. Analysis was performed for the whole group and separately for subjects who did and did not view an ABS instructional video prior to testing.
Across all drivers, inputs were inconsistent with the idea of multiple brake applications to a force near the limit of the car's deceleration capability interrupted by a complete release of the pedal, supporting a hypothesis that drivers typically simply apply the brakes to achieve a desired rate of deceleration.