More and more intersections with traffic signals are being installed with vehicle detection loops. These loops are installed in the pavement behind the stop bar in left turn lanes and through lanes. When a vehicle stops on top of one of these loops, the controller receives an indication that a car is waiting for a green light. The controller then begins to complete its current function so it can give a green light to the waiting vehicle.
The stop bar is located at intersections so that a driver stopped at that spot has the best view of the traffic signals. The loops are placed behind the large white stop bar at the intersection. If a vehicle stops too soon, pulls up too far or even creeps up slowly past the stop bar, then the loop does not give an indication that someone is waiting to receive a green light. If the controller does not receive such indication, it will not give a green light to that car until another vehicle pulls up behind the 1st one and actuates the loop.
Stop Here on Red Signs
Stop here on red signs usually indicate that there is a loop in the pavement, however, there isn't always a sign. Stop at the stop bar for the best view of the traffic signal, to actuate a loop, and to provide the highest level of safety for everyone.