Prior to commonplace ABS in cars, pumping the brakes when traction was bad was a commonplace braking technique taught across Canada for winter driving. An added

Prior to commonplace ABS in cars, pumping the brakes when traction was bad was a commonplace braking technique taught across Canada for winter driving. An added benefit was that the sudden, irregular flashes of brake lights ahead hopefully gave a good amount of warning to following drivers to let off their own gas pedal and do the same kind of brake pumping.