brake reaction distance; brake lag distance
Technical term in driving and traffic engineering: the distance a vehicle travels from the moment a driver perceives a need to stop until the brakes are actually applied. Often contrasted with 制動距離 (braking distance) and 停止距離 (stopping distance).
The brake reaction distance is determined by the driver's reaction time and the vehicle's speed.
The stopping distance is the sum of the brake reaction distance and the braking distance.