Abstract: Restraint for preventing inadvertent horizontal movement away from a loading dock of a vehicle on a driveway adjacent the loading dock, the restraint comprising an elongated restraint arm including a bracket at a first end thereof shaped to engage a component of the vehicle, the restraint arm being connected to the driveway for movement of the first end between a lowered position proximate the driveway and a raised position wherein the bracket is disposed to engage the vehicle component, a piston-cylinder arrangement for selectively biasing the restraint arm to the raised position, and a cam structure at the second end of the restraint arm for locking the restraint arm in the raised position in response to a horizontal force acting on the restraint arm in a direction away from the loading dock and for permitting movement of the restraint arm between the raised and lowered positions in response to a horizontal force acting on the restraint arm toward the loading dock or a vertical force acting on the restraint