What is Intelligent Transportation Systems?
Variable speed limits in action on westbound SR 520 in Bellevue.
Intelligent Transportation Systems (ITS) is the technology that runs parallel to almost every mile of our state highway system. This technology makes up our Communication Backbone. It is composed of wireless, radio, microwave and fiber optics that help us manage the roadways through our Traffic Management Centers (TMC). It also provides traveler information to commuters. Information transmitted over the system comes from many ITS elements that are part of our overall traffic management efforts. ITS elements include:
- Active Traffic Management (ATM) – ATM is the newest technology in our congestion relief program. It allows us to add new roadway capacity and manage the demand through peak commutes and during incidents.
- Traffic Cameras (CCTV) - We operate an extensive network of closed-circuit television across the state to help detect congestion and incidents. The camera images are sent to our TMCs for operations monitoring, to the Web for travelers and to the media.
Variable Message Signs (VMS) - A VMS is an electronic traffic sign used on roadways to provide motorist with important information about traffic congestion, incidents, roadwork, travel times, special events or speed limits on a specific highway segment. They may also recommend alternative routes, limit travel speed, warn of duration and location of problem or simply provide alerts or warnings.
Example of a VMS Sign-Border Wait Times
- Highway Advisory Radios (HAR) - HARs are licensed low-power AM radio stations installed along the roadway to provide alerts and general information regarding traffic and travel. The presence of a HAR transmitter is marked by a roadway sign instructing motorist to "Tune to a specific AM frequency".
- Road/Weather Information Systems (RWIS) - RWIS stations are installed along the roadway with instruments and equipment, which provide weather and road surface condition observations. We use this information to help with decisions on maintenance strategies and to provide information to drivers. These stations may measure air and road surface temperature, barometric pressure, humidity, wind speed and direction, precipitation, visibility and road surface condition (dry, wet, freezing).
- Ramp Meters - Ramp meters are traffic signals on freeway on-ramps that alternate between red and green to control the flow of vehicles entering the freeway mainline. Metering rates are adjusted automatically by the system based on prevailing freeway traffic conditions.
- Traffic Data Collectors - Traffic detectors are one of the key set of tools used to keep track of what is happening on the roadways. The most common detector we use is the induction loop, a simple low-voltage wire coil buried in the roadway that sends an electrical pulse when a vehicle passes over it. Other, less common detectors use infrared, radar, sound or video imaging to detect vehicles. The detection data is sent from the roadside to the TMCs to monitor operations and provide traffic conditions to the Web and the WSDOT 511 traffic information hotline.
- Traffic Management Centers (TMC) - WSDOT operates six regional TMCs . They are the nerve centers for our operations activities. Real-time information is gathered 24 hours a day, 7 days a week from many sources including traffic detectors, CCTV cameras, ramp meters, the Washington State Patrol (WSP), road crews, WSDOT's incident response teams , and media traffic reporters. We use this information to respond to incidents, deal with other problems that occur, and notify the public and the media of these events.
We have six TMCs that are located in Shoreline, Tacoma, Vancouver, Wenatchee, Yakima and Spokane. Each varies in capabilities and size to meet regional needs. The centers in Tacoma, Vancouver, Spokane and Yakima are co-located with other operating agencies. We also have a winter operations center on Snoqualmie Pass.
Key ITS Operations Offices: