Bob is barreling down the thruway in his truck at 40 m/s when a crash occurs in front of it. The driver wants to stop in the shortest distance possible. He slams on the brakes. Before the invention and implementation of the Anti-lock brake system, or ABS, the truck's tires would have locked up and the truck would have slid into the crash.
When brakes cause tires to lock up, the type of friction between the tires and road changes from static friction to kinetic friction. This decreases the total force of friction between the surfaces. Because of the decrease in force opposing the truck's motion, the truck cannot stop in a short distance.
How does the ABS prevent this?
The Anti-lock brake system prevents the tires from locking up. Therefore, the type of friction between the tires and the road is always static, the strongest type of friction. The implementation of ABS into modern cars and trucks has prevented crashes from panicked drivers, such as Bob, by allowing them to come to a complete stop in shorter distances than before possible, even better than experienced drivers using advanced braking techniques without ABS.