The tube needs only to be tapped lightly to count a passing vehicle. An automobile, motorcycle, bicycle and even a pedestrian walking over the tube are counted as one vehicle. To determine what type of vehicle has caused a pulse, two tubes must be stretched across the road, spaced apart, to record the axle spacing of the vehicles at the count location. If anything made of metal passes over it a count is sent to a controller box. The controller box then determines whether or not the light should turn or remain green.
Detector loops are very reliable, and relatively inexpensive to produce, install and maintain.
A person sitting at an intersection pushes buttons on an electronic board as cars pass by. Hand counts are done to record how many cars have turned right, left or gone straight through a busy intersection or for classification counts.