The City Of Lewiston

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Idaho's Only Seaport
Traffic Signals
The City has 35 traffic signals and 36 warning flashers.
  • Three signals owned by the State of Idaho are maintained by the City under a maintenance agreement between the City and State.
  • Six signals in the downtown area have preset timing intervals and do not change with the traffic volume.
  • Remaining signals are traffic actuated from 6' x 6' wire loops embedded in the pavement and are known as traffic detection loops. These loops detect vehicles as they approach the traffic signal and send information to a control cabinet located on a corner near the intersection. The traffic control cabinet then assigns most of the available green time to the heaviest traffic movements. Traffic signals on 21st Street, Thain Grade, and Thain Road are in a coordinated system; the goal of which is to safely move the greatest number of vehicles through the system with the fewest number of stops.

Waiting Time
In the traffic control box, priority is programmed for the main arterial, or the street with the majority of traffic. This means that vehicles traveling on side streets entering a street like 21st have to wait longer for a signal to change.

Emergency Vehicles
Some signalized intersections also have emergency vehicle preemption, meaning the emergency vehicle will have a preprogrammed green light priority. The purpose is to allow the emergency vehicle to pass through the intersection as quickly and as safely as possible.