run away truck braking systems do they have one?

by gary
(portland or)

i am a car driver, and know nothing about big rig trucks, but i was wondering.... if a truck is a run away, is there an emergancey braking system, that if a car hit the back of a trailer rig it will apply an emergecy braking system to help stop the truck... like a State Patrol would apply it for a truck racing out of control?