The Electricians in the Streets Division of the Public Works Utilities and Operations Department oversees the operations and maintenance of the City’s traffic signals, lane lights, and flashing signals at over 6,600+ all across the City.

Special Signal Functions 

Traffic 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.

	Flashing Red 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.
	Flashing Yellow 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.
	Dark Signals 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 Utilities and Operations Department at (530) 757-5686 or, if after hours, the Davis Police Department at (530)747-5400.

Power Outages and Traffic Signals

In the event of a power outage, only a few of the City’s traffic signals (at major intersections) have battery backups. The most common occurrence during a power outage would be that the signals “go dark” (do not operate). Flashing only occurs during malfunctions of signals with power. Those signals with battery power backups will operate during an outage as normal until the battery runs out, when they will also go dark. Power outages will vary in the number of intersections impacted and in the duration of the outage. When the power is off at a signaled intersection, the intersection becomes a four-way stop. Often, power is restored in a short period of time, and signals will return to normal function, or revert to a flashing mode if there is an electrical malfunction, so drivers are advised to use caution at all times when approaching an intersection without power. Stop signs are not placed in intersections during an unexpected power outage. Stop signs are placed only when the outage is planned and work is taking place.

Scheduled Traffic Signal Outages

When repairs or work on the signals are necessary, the City’s electricians will schedule an outage for traffic lights. The signal will first be placed into flash to slow down traffic, before the power is shut off. When the crew is present and work is taking place, stop signs will be placed in all four directions for traffic control and safety. When work is completed, the power will be turned back on and the signal will start in flash mode. Normal operation for the signal can begin when the stop signs are removed, and the signal is returned to full function. 

Traffic Signal Malfunctions

Severe storms, wind events, and other factors can affect the ability of a traffic light to function normally. When a traffic signal malfunctions, but still has power, it will revert to a flashing mode. Drivers approaching a flashing signal light must make a complete stop before proceeding into the intersection when safe (the intersection is now a four-way stop). Signals in flashing mode can revert to normal function at any time, and without warning, so always proceed with caution when approaching intersections with flashing signals. 

When a signal is placed into flashing mode for a repair, and crews are on scene, often stop signs will be placed in the intersection to guide traffic and maintain safety. However, signals impacted by weather events or accidents will most likely not have stop signs posted. During weather events especially, dispatching equipment and personnel can be complicated, and often focused on responding to malfunctioning equipment based on established emergency response protocols.