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Intelligent Transportation Systems (ITS)

Last updated: December 3, 2015

Here at the Seattle Department of Transportation (SDOT), we use a variety of technologies to improve multi-modal travel across the city. These technologies are known as Intelligent Transportation Systems, or ITS. ITS plays a key role in a safe, efficient, and innovative transportation system that works for all travelers. When people know what’s going on in real-time, they can make more informed travel choices.

Click on one of the pictures below to see how ITS can help you! You can also learn more about how we utilize ITS by watching this video.

ITS improves transportation safety and mobility through the integration of advanced technologies into the transportation infrastructure. Much of what we do is not visible to the traveler. At the most basic level, ITS technologies:

  • Detect vehicles and people in the street.
  • Sends this information to a computer located either in the field, such as at an intersection, or to a central location (the SDOT Transportation Operations Center or TOC), for processing and action by computer systems or by staff to improve operations.

The following provides an overview of some of the ITS services that we use in Seattle.

SDOT’s Transportation Operations Center (TOC)

The heart of ourITS infrastructure is the Transportation Operations Center (TOC). We gather real-time information via traffic detectors, CCTV cameras, ramp meters, and information service providers. We use this information to better manage traffic incidents and let the general public and media know what’s going on.  At the TOC, we manage incidents from 6 AM – 10 PM daily and remain on-call after hours, making us 24/7 capable.

  • 200 Traffic Cameras
  • 34 Dynamic Message Signs
  • 12 corridors with travel times on the Dynamic Message Signs
  • Travel times posted to web for the 12 corridors and the entire downtown area
  • Congestion monitoring on an additional 10 corridors posted to the web
  • 1100 traffic signals, including 6 corridors where the signals respond to traffic volumes
  • An estimated 25 incidents that affect traffic every day
  • 100 major events or road closures every month
  • Travelers web site (and iPhone app, plus Twitter feed)

Managed Incidents Report

In the TOC, we record the number of incidents managed as they occur throughout Seattle. The graph below summarizes the number of incidents managed each month for the past few months. When an incident occurs, we notify the public via Twitter and Dynamic Message Signs. We also coordinate with the appropriate agencies to ensure that the impacts of the incident is effectively mitigated. This also includes communicating with our Maintenance & Operations Division to get SDOT presence at the scene of the incident so we can get updates quickly.

One of our goals in the TOC is to identify potential conflicts such as construction projects and special events earlier to allow for planning efforts that could save time and money.  Some closures are larger and with this coordination effort, it can be done in such a way that will allow for more work to be completed within the closure area and prevent multiple impacts to the traveling public.  That said, in-street construction will cause congestion but the impacts can be minimized by providing information early to the public so they can better plan their trips. For information on future construction projects, visit our Construction Look Ahead website.

Closed Circuit Television (CCTV) Cameras are also controlled by our TOC. We have cameras installed throughout the city to monitor congestion, incidents, closures, and other traffic issues. The ability to see the roads provide our engineers with the necessary information to manage the incident and identify alternate routes. It also helps our staff send out critical information to the public through means such as Dynamic Message Signs, our Twitter feed, and the Traveler’s Information Website. You can see where our cameras are installed here

Travelers on one of Seattle’s major corridors may have noticed these electronic signs. These Dynamic Message Signs (DMS) are controlled by our TOC to send out information relating to traffic such as incidents, bridge closures, travel times, congestion, and lane closures. With this type of information displayed, drivers can make real time route choices given the traffic conditions ahead. You can see where our DMS’s are installed here

In some circumstances, important messages need to be relayed to drivers where DMS’s are not installed. An example of this is construction projects that result in closed lanes. In such cases, we deploy Portable Changeable Message Signs (PCMS). Many PCMS’s have to be manually programmed in the field; others can be remotely programmed from a computerized center such as the TOC. We own and operates both types of PCMS’s.

The Traveler’s Information Website was launched in March of 2009. The website contains an interactive map where the public can view still images and video from our traffic cameras; it provides real time traffic conditions and travel times throughout the city, and provides information on planned special events and major incidents. The traffic images are updated every minute and the video feeds are live streaming. Travel times can be accessed at certain key points throughout the city so travelers can better plan their trip. An iPhone application is also available for download on the website.

Another way to get real time information about traffic conditions is by following our Twitter feed @seattledot. We tweet about incidents, travel times, congestion, and other events that occur on Seattle owned streets. By following the Twitter feed, travelers can get quicker updates on incidents that may affect their travel.

In addition, we also maintain a separate account for bridge openings and closures. By following our Bridge Twitter feed @SDOTbridges, users will receive real-time tweets regarding bridge operations in Seattle. Bridges that we tweet about includes 1st Ave Bridge, Ballard Bridge, Fremont Bridge, Lower Spokane Bridge, Montlake Bridge, South Park Bridge, and University Bridge.

Many of our traffic signals work cooperatively with wireless sensing technology and detectors to manage traffic and maximize roadway efficiency. When traffic volumes are high, the traffic signal control system can adjust timing plans accordingly to respond to changes in demand. Many of the signals’ operational systems are based on historic data for the time of day. On some corridors, when traffic demand exceeds a certain threshold, the signal timing will adapt to that extreme. We call this our Traffic Responsive Operation.

Transit Signal Priority (TSP) is provided on Rapid Ride corridors, and uses wireless communications to allow buses and traffic signals to communicate with each other. When the signal detects that there is a transit vehicle approaching, it can extend the green time or shorten the red time for the vehicle if the current situation allows for it.

On many of Seattle’s roadways, bike detectors are installed to create more optimized trips for bicyclists. When a bicyclist is found on a detector, it communicates with the traffic signal control system so that it is aware there is a bicyclist waiting. This allows for the traffic signals to change lights appropriately.

Count-down signals are used along with conventional pedestrian signals to provide information to pedestrians regarding the amount of time remaining to safely cross the street. With more information provided on the transportation facilities, pedestrians can make more informed decisions.

ITS Strategic Plan provides a 10 year approach for implementing ITS in Seattle. We have been implementing ITS for many years, primarily to address multi-modal operations at traffic signals. Implementations have included many of the ITS elements and infrastructure mentioned above.

The investments and infrastructure in place provide a core set of services. This infrastructure must be maintained to ensure safe, reliable, and efficient operations. The ITS Strategic Plan identifies this as the ITS “Core Infrastructure.” ITS Core Actions were identified in the plan:

  • Continue controller/cabinet and equipment upgrades
  • Expand deployment of detection at traffic signals
  • Expand deployment of fiber optic communications network
  • Implement Systems that increase the reliability of the ITS Core
  • Maintain and/or upgrade existing and implement new systems at the TOC
  • Continue deployment of ITS equipment on the ITS key arterial network

Using ITS is a cost-effective way to optimize transportation operations without investing in large projects to modify the infrastructure. Our NextGen (Next Generation) ITS Strategy identifies construction projects that will result in major traffic impacts to the city’s transportation system and proposes ITS solutions to mitigate them. Reports were created to detail the NextGen ITS Strategy and can be accessed via the following links:

Task 1: Construction Mitigation
Task 2: Next Generation TMC
Task 3: ASC Corridor Implementation
Task 4: ITS Parking Strategies
Task 5: Implementation

How will we use ITS to further enhance transportation in Seattle? There are plans to use emerging technology to make traffic operations more efficient and safe in the City. Learn more about technology improvements we hope to make in the next 10 years in our Move Seattle plan (specifically, pages 14-15).

For other ITS related questions, please feel free to contact us at

Traffic Operations - What We Do & How We Do It

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