A ramp meter, ramp signal, or metering light is a device, usually a basic traffic light or a two-section signal light together with a signal controller, that regulates the flow of traffic entering freeways according to current traffic conditions. Ramp meters are used at freeway on-ramps to manage the rate of automobiles entering the freeway. Ramp metering systems have proved to be successful in decreasing traffic congestion and improving driver safety.
Metered ramp on I-894 in the Milwaukee area.
A Portland, Oregon ramp meter
A Milwaukee, Wisconsin ramp meter
Ramp Metering on the A19 in Middlesbrough.
Traffic lights, traffic signals, or stoplights – also known as robots in South Africa and Namibia – are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.
An LED 50-watt traffic light in Portsmouth, United Kingdom
Traffic lights can have several additional lights for filter turns or bus lanes.
Horizontally-mounted signals in Japan
A traffic signal in Halifax, Nova Scotia, with specially shaped lights to assist people with colour blindness