Working for a safe, affordable, vibrant, innovative, and interconnected city.
Learn More Home Page This Department
Link to Transportation Home Page Link to Transportation Home Page Link to Transportation About Us Page Link to Transportation Contact Us Page
Delivering a first-rate transportation system for Seattle Scott Kubly, Director







Site Index

Intelligent Transportation Systems (ITS)

Last updated: December 2, 2014

What are Intelligent Transportation Systems?

An intelligent transportation system (ITS) is a subtle but very important technology infrastructure. An ITS applies emerging hardware and software to the challenges of transportation congestion. It is also an effort to provide real time information to roadway users in order to improve safety, travel times and reduce fuel consumption.
Systems utilize different key elements including:

  • Countdown pedestrian signal heads
  • Intelligent signal control systems
  • Dynamic Messaging Signs (DMS)
  • License plate readers
  • Closed circuit TV (CCTV) systems

And more advance applications such as transit signal priority and traffic responsive operations. An ITS may also use live data to modify roadway control parameters and provide this information to current users through the Traveler’s Information Web page.

SDOT’s Traffic Management Center (TMC)

SDOT operates a single Traffic Management Center (TMC). It is the nerve center for SDOT’s operations activities. Real-time information is gathered from many sources including traffic detectors, CCTV cameras, ramp meters, WSDOT, road crews, incident response teams and the media. SDOT uses this information to coordinate responses to clear incidents that occur and notify the general public and the media of these events.

Dynamic Message sign


Elements of an Intelligent Transportation System:

Count down signalThe City of Seattle’s Department of Transportation (SDOT) operates a communication system composed of radio, microwave and fiber optics elements that touch all sections of the road network. It provides radio communications for those maintaining the roads and data transmission for those managing the roads. The data that is transmitted over the system comes from many ITS elements that are part of our overall traffic management efforts.

Count down signals are used in conjunction with conventional pedestrian signals to provide information to the pedestrian regarding the amount of time remaining to safely cross the street. Pedestrians will use this information to make better decisions about when to enter the crosswalk.

We are able to populate our traffic signals with wireless sensing technology to manage the increased traffic volume data and maximize the efficiency of the roadway. When the volume of both pedestrians and vehicles are low the traffic signal control system can bypass optimized timing routines and operate the intersection to respond to the detected demand.

Dynamic Message sign Dynamic Message signs (DMS) are used to give travelers information that can be used in making real time travel decisions. Such information might provide motorist with important information about traffic congestion, incidents, roadwork zones and projected travel times. These signs may also recommend alternative routes, limit travel speed, warn of duration and location of problem, or simply provide alerts or warnings.

Traffic Cameras (CCTVs) help SDOT detect congestion and traffic incidences and stay constantly aware of road conditions. The up-to-the-minute camera images are sent to our traffic management center for operations monitoring, to the web and dynamic messaging signs for travelers, and to the media. Operators also use the information gathered from the cameras to make operational changes to signalized intersections.

Traffic camera The Traveler’s Information Web site – website was launched to the public on March 26, 2009.  The map uses an interactive format and live traffic data to display traffic conditions for both city arterials and state highways on one map. Traffic camera images can be viewed by hovering on camera icons. Incidents, planned events and links to other key transportation sites are also posted to the website.

Transit Signal Priority uses a detection system to accommodate buses. SDOT currently has a few intersections running Transit Signal priority operations. This system detects buses as they approach signalized intersections. If a bus is detected and the signal is about to turn red for the bus, the signal instead will extend the green light for the bus in an effort to reduce delays for riders. SDOT is currently updating many signal cabinets for the future Rapid Ride Transit Corridors to support this operation.

Traffic Responsive Operation Systems are considered one of the most effective operational modes in traffic signal systems. SDOT’s current operation relies on historical data to develop patterns to fit the time of the day needs. Although the methods of using historical data works well for the most part, this breaks down whenever there is an unexpected increase in volume due, for example, to an incident or unexpected detour. In this case the traffic responsive operation system will take into account the volume increase and select from pre-evaluated patterns to fit the needs of the roadway. The traffic responsive operation system will also respond to unexpected low volume by reducing the background cycles to reduce delays.

ITS Strategic Plan

This plan provides a 10 year approach for implementing Intelligent Transportation System (ITS) in Seattle.  An ITS employs electronics and communications technologies on the street and automated traffic systems to enhance mobility for all modes by increasing the efficiency and safety of the transportation infrastructure.

The Seattle Department of Transportation (SDOT) has been implementing ITS for many years, primarily to address mulit-modal operations at traffic signals. Implementations have included:

  • Enhancing operations by adding communications links, installing new traffic signal controllers with additional capabilities, and increasing the frequency of traffic signal timing updates.
  • Using automated systems that detect congestion and change signal timing to speed traffic  clearance from special event venues (Key Arena, Safeco Field, Seattle Center, Benaroya Hall), from bridge opening, ferry off-loading, and rail crossings.
  • Improving traffic signal operations for all modes by adding detection for pedestrians, bicycles, and vehicles, and by installing improvements to vehicle and pedestrian signal displays, including audible displays for visually impaired pedestrian.
  • Installing and operating transit signal priority (TSP), and other transit systems for buses, streetcars, and light rail trains.
  • Implementing traffic cameras citywide to improve the response to outage and incidents.
  • Providing public area access to traffic information by implementing a website that includes real-time congestion information, traffic advisories and images from traffic cameras.
  • Deploying Dynamic Message Signs (DMS) to provide targeted traffic messages to drivers en route.

The investments and infrastructure in place provide a core set of services.  This infrastructure must be maintained to ensure safe, reliable and efficient operations, and properly managed to realize a positive return on the investment.  This Strategic Plan identifies this, the ITS “Core Infrastructure” as:

  • Traffic signal controllers, cabinets, detections and displays
  • The citywide ITS communications network
  • Traffic cameras that enable staff to view operations and dynamically adjust traffic signal timing if needed
  • DMS that provide on-street traveler information
  • The traveler’s website ( that includes congestion information, traffic advisories and traffic camera images.
  • The Traffic Management Center (TMC) that includes processing, monitoring, and communications equipment allowing staff to interact with the systems.
  • The staff that operate and maintain these assets.


Home | About Us | Contact Us | Site Index | News | FAQs | E-Mail Alerts