What is... Traffic Signals?

Traffic Signals are principally used as a safety feature to separate conflicting traffic flows, where spatial or financial restrictions result in the different movements not being physically segregated. This is achieved by temporal segregation, within the available road-space, in a safe, efficient, and equitable manner for all road users.

Although mainly used to control vehicular traffic, signals make a major contribution to the safety of vulnerable users with the provision of facilities for pedestrians, cyclists and even equestrian users. Traffic signals are a ubiqutious roadside feature across the world, however the adoption of more complex technolgies has resulted in the capability of signal installations being hugely improved. The advent of new communications capabilities and increasing computing processing capacity within traffic signal controllers has had a significant impact. Along with these, features such as:

- The use of Light Emitting Diodes (LED's) and energy efficient modern electronic assemblies contribute to dramatic energy savings compared with traditional systems

- New technologies used for detecting vehicles and other users, such as pedestrians and cyclists, making systems more responsive to current demand

- Enhanced integration with Urban Traffic Control Systems to synchronise individual intersection operation across highway networks

Other uses for traffic signals include Ramp Signalling, which overcome congestion issues caused by large numbers of vehicles joining the motorway, by 'metering' the flow of vehicles on the On Ramp.

For more information on traffic signals, have a look at our comprehensive book on the subject - Traffic Signals - the book