You must have seen the barricades used by the traffic police of various cities at checkposts to stop the vehicles. Now such a barricade can be easily toppled over by anybody and so it cannot be used to force a real speeding vehicle to stop and it certainly cannot be used to stop a mob.

The problem is : Can you suggest a simple change to the barricade which will make it suitable to be used to really force the speedy vehicles to stop and more importantly, make it useful to handle a mob easily ?