We have a variant of this installed on a tunnel (which is probably safer, but not as cool :) ): Directly after the last highway exit before reaching the tunnel

We have a variant of this installed on a tunnel (which is probably safer, but not as cool :) ): Directly after the last highway exit before reaching the tunnel is a light barrier installed. If something breaks the barrier the tunnel entrance will be closed by boom barriers (and warning lights, so nobody drives into the boom barriers). Then the police drives out to the tunnel, finds the culprit, pulls him out and unlocks the tunnel again. Obviously, this only works because there is enough time after the last exit to block the tunnel before the truck reaches it.