Not heavy enough. The lines in the ground work by pressure altering the electrical properties of a cable. When enough weight is on it, i.e a car, bus, or truck, it will alter the electrical properties enough that the sensor picks up the change. Lighter objects like people, dogs, cats, bicycles, they won't push down with enough force.
In that case what about motorbike? A small-size guy in a small 125cc motorbike heavy enough to trigger the sensor? A big fat man riding a bicycle will trigger the sensor as well?
