I remember being taught this method of ambush/hasty defense. Normally a "volunteer" would be in hiding along side the roadway in a very confined area where vehicles can not go. The tanks would be buttoned up and their vision will be very limited on the sides of the road. In a lots of cases the tank commander and drivers will not see the rope lying across the roadway. At the last minute the mines are pulled across the roadway into the tracks of the tank. With track blown off the tank would be immobilized blocking the roadway. If properly done the same situation should happen to the last tank in convoy thus blocking any escape from destruction. The anti-tank mines used requires about 500 lbs of direct pressure to set them off. So there is no real danger of setting them off when they are dragged in front the tank.