Driving Safety News

Traffic Light Operation

Traffic light signals are generally timed or are set to be responsive to traffic conditions particularly when signals are run exclusively on timers.  Each direction of traffic flow is designated a particular duration of 'environment-friendly' time for its particular lane conditions to suit the prevailing traffic conditions at set periods during the day.


Traffic receptive signalling lights run using a mix of vehicle detecting devices or sensors in conjunction with timing systems and devices. When a traffic light signal is operated in this fashion, for instance, the light on the major road could remain in green for go forward mode at all times unless another vehicle is discovered approaching on an adjacent road.


Detectors can be utilized to establish when a vehicle gets to a pre-determined crossing point. In the event that way too many vehicles are getting “backed up” at an intersection or when vehicles have actually already moved forward into a turn lane (in order to trigger the traffic control lighting to change sequence).


This explains why it appears a driver may need to wait longer to move forward on a green light above their own lane as well as why they might not get a “green for go” light every single time they come to a certain intersection.


Have you ever before wondered how a traffic light "knows" you are there?


Many individuals believe that there are sensors in the road that identify the weight of a vehicle stopped on top of them. However, in practice this is often not the case at all.


There are all types of different detection technologies for vehicle control. From lasers to electronic cameras to rubber hose pipes loaded with air.


One of the most common method, without a doubt, is an arrangement normally referred to as an “inductive loop” system. An inductive loop system is merely a coil of special cable carefully embedded under the road’s surface.


This arrangement then acts somewhat like a magnet. When a vehicle drives over or stops on the “inductive loop”, metal in the car alters the magnetic field; the special cable detects the vehicle’s presence and informs a signal controller that an oncoming vehicle is now approaching the traffic lights.


Sometimes loops are set up entirely underneath the asphalt surface of a road and are completely invisible to the naked eye. In other instances, a groove is placed in the asphalt with a mechanical saw; the special cable is laid in this groove and then sealed with an elastomeric compound. Drivers can frequently see these huge rectangle-shaped loops in the road’s surface due to the fact that the elastomeric compound’s colour is noticeable.


The signal controller is the 'brain' of a traffic lights signalling system. It manages the selection and also timing of traffic movements based on varying demands of traffic as identified by the detectors.


The controller at one intersection could additionally interact with controllers at various other intersections and can be programmed to co-ordinate signals during peak traffic periods using timed interval operation hours to make best use of the effectiveness of directional traffic flows.