Create a Thriving Business District

TRAFFIC SIGNALS

Seattle is a growing city without a lot of space to build new roads. The Seattle Department of Transportation (SDOT)’s signal operations engineers therefore work with our existing network of streets, bridges, highways and traffic signals to effectively manage and improve the safety and functionality of the traffic system.

If your organization identifies one or more intersections that might need a traffic signal, call Joe Couples at SDOT Signal Operations, 206-684-5246. SDOT will begin an analysis to determine how the intersection measures up to City and Federal criteria used to determine the need for traffic signals. They will make a visual inspection, check crash history, measure pedestrian and car volumes and talk to the citizen or business person who reported the problem.

If the intersection merits a signal, then the location will be placed on the “new signal needs list.” Each year, a number of locations are identified for construction from the signal needs list. The number varies from year to year based on available resources.

If the intersection does not have enough traffic volume (pedestrians and vehicles) to merit a signal, SDOT will examine alternatives such as: using larger stop signs, painting a wider stop bar, increasing lane markers to better direct traffic or devising an alternate routing such as a right turn only designation.

Frequently asked questions:

How do we request pedestrian signals or crosswalk lights ?

SDOT does not generally install crosswalk lights because they have not proven to be very effective (crosswalk lights are blinking yellow lights above a crosswalk). Pedestrian signals allow pedestrians to push a button and change the traffic light in order to cross the street. The process for requesting a pedestrian signal is similar to requesting traffic signals. SDOT will do an accident analysis and if the intersection merits a signal, it will be placed on the new signal needs list. The cost of a pedestrian signal is less than a full signal.

How long does the signal request process take?

If a location is determined to merit consideration for a signal, it could be up to a year after the completion of the signal warrant study. After funding is approved in the City’s budget process, the signals are designed, parts are ordered and construction usually takes place between April and October. For requests that do not merit consideration, the study results are usually available in six to twelve weeks.

Benefits and challenges of new signals :

BENEFITS

• Increases safety and may reduce the number of “right-angle” crashes.
• May reduce side street crossing delays.

CHALLENGES

• May generate overall increase in traffic volumes on surrounding street or increase “rear-end” accidents.
• Can interfere with smooth traffic flow. It is optimal to have both directions of the major arterial flowing. Sometimes one or both directions can be stopped when a new signal is installed.