Signal Operations

As a subset of operations & supporting infrastructure, this category includes strategies related to signals and signalization.

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  • Adaptive signals change traffic signal timings based on current traffic conditions. Using hardware, adaptive signals measure the traffic conditions of vehicles, bicyclists, and pedestrians and then utilize software to make timing changes based on the real-time data.

  • Emergency vehicle preemption (EVP) interrupts normal traffic signal timing to provide a green light to approaching emergency vehicles so that they can pass through intersections to get to emergencies safely and quickly.

  • Freight (or truck) signal priority (FSP) provides extra green light time so that a heavy truck can move through a traffic signal without stopping.

  • Planned event or incident signal timing synchronizes groups of traffic signals to favor traffic entering and exiting a special event venue or area in order to minimize congestion. It can also be used to divert traffic around an unplanned event, such as an incident or a regionwide evacuation.

  • Proactive signal timing review and optimization uses actual traffic performance data to operate and manage traffic signals. This strategy can help improve safety, reduce vehicle delays, and help more finely target maintenance activities.

  • Signal timing review and optimization synchronizes groups of traffic signals so that vehicles on a primary route can travel through multiple traffic signals without stopping. It can also reduce vehicle wait times at individual intersections by adjusting the length of green lights to match demand.

  • Traffic signals are an essential, cost-effective tool to manage the movement of traffic and provide solutions to a variety of mobility, safety, and system management goals. However, traffic signals are sometimes an unnecessary expense that can add to collisions, congestion, and delay.

  • Traffic signal priority and preemption settings modify the traffic signal timing and give priority to specific vehicle types, such as buses, light rail, streetcars, trucks, emergency vehicles, or trains.

  • Transit signal priority (TSP) makes it more likely that the light is green when a transit vehicle reaches a signalized intersection. This strategy reduces travel times for transit vehicles by avoiding the need to stop and start at signalized intersections.