Traffic signals –the familiar red, yellow and green lights--as well as the specialized pedestrian lights, are designed to let people know who has the right of way at an intersection or crossing.
Traffic signals help manage traffic flow, allow pedestrians to cross, and give cross-street traffic a chance to enter the intersection.Pedestrian signals allow people to cross an intersection safely. Traffic engineers install pedestrian indicators on traffic signal posts using lighted words or symbols to indicate when it is safe to cross. New pedestrian signals use symbols which make it easy to understand by everyone.
Traffic Signal Coordination
Traffic signal coordination occurs when a group of two or more traffic signals are working together. The goal of the signal coordination is to establish platoons of vehicles that can move easily from one intersection to another without stopping, to improve efficiency and minimizing delay. In traffic signal coordination, the busiest traffic movements are given precedence over the smaller traffic movements. Although arterial streets benefit from signal coordination, some of the benefit is offset by increase in stops and delay to the side street traffic. If the motorist is waiting for a green light to cross the "coordinated" street where there is heavy traffic on the main street and very light traffic on the side street, they will probably feel like they are waiting for a very long time. In the past, coordinated signals have been removed from some of the corridor segments due to complaints about the side street delay.
Special Signal FunctionsTraffic Signal Preemption
The transfer of signal control to a special signal operation is called preemption.
Emergency Vehicle Preemption
Emergency vehicle preemption can be used for any authorized emergency vehicle, in Davis fire engines and marked Police cars are the only vehicles equipped with the necessary devices. The purpose of preemption is to obtain a green light for the emergency vehicle as soon as possible or to prolong an existing green light. To obtain a green light on the intended route, existing green light cycles for opposing movements, including pedestrian intervals, are abbreviated. After the yellow change interval, a green light is given to the approach to be used by the emergency vehicle.
According to the California Vehicle Code, when a red lens is illuminated with rapid intermittent flashes, a driver shall make a full stop before entering the crosswalk on the near side of the intersection. The driver may then proceed, subject to the rules applicable to making a stop at a 4-way stop controlled intersection.
When a yellow lens is illuminated with rapid intermittent flashes, a driver may proceed through the intersection or past the signal when it is safe to do so.
When a traffic signal has gone dark due to power failure it is considered to function the same way as a 4-way stop controlled intersection and a driver must stop and observe standard right of way rules before entering the intersection. Always stop at a darkened intersection, and then proceed with caution. Be extra alert since normal traffic patterns will be disrupted. Also, use extra caution when approaching railroad crossing. If you see traffic signal lights that are not working, please notify Public Works at (530) 757-5686 or, if after hours, the Davis Police Department at (530)747-5400