Deployment of a Virtual Sensor System Based on Probes, in an Operational Traffic Management System

The Washington State Department of Transportation (WSDOT) operates a central traffic management system (TMS) for both day-to-day surveillance and traveler information. Past efforts developed the ability to create real-time traffic speed information by using virtual sensors that are based on transit vehicle tracking data. This project developed a way to provide real-time congestion information from Seattle area arterials and freeways to the WSDOT TMS by using the Intelligent Transportation System Backbone. This system harvests existing automatic vehicle location (AVL) data from within King County Metro Transit and transports the raw data to the University of Washington, where a series of operations converts the data into roadway speed information. This roadway speed information is color coded on the basis of specific, localized conditions for the arterials and freeways to reflect traffic congestion. The resulting traffic data product is then provided to WSDOT as a virtual sensor data source for roadways where presently there are no inductance loops. The project also created several user interfaces for traveler information, including a Java application that displays the spatial and temporal average speeds of transit vehicles on a map of the major arterials and freeways and a type of traveler information map. This report also includes a quantitative evaluation of transit vehicles as traffic probes. A comparison of statistics between virtual sensors based on transit vehicles as probes and those from speed traps presently used by WSDOT suggested this virtual sensor technology can be used to identify both recurring and non-recurring congestion with the accuracy associated with speed traps. This means that additional roadways that do not presently have speed traps can be instrumented without installing equipment in the roadway.

  • Record URL:
  • Corporate Authors:

    Washington State Transportation Center

    University of Washington, 1107 NE 45th Street, Suite 535
    Seattle, WA  United States  98105

    Washington State Department of Transportation

    Transportation Building, 310 Maple Park Avenue SE, P.O. Box 47300
    Olympia, WA  United States  98504-7300

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Dailey, Daniel J
    • Cathey, Frederick W
  • Publication Date: 2006-11


  • English

Media Info

  • Media Type: Print
  • Edition: Technical Report
  • Features: Figures; Maps; References; Tables;
  • Pagination: 38p

Subject/Index Terms

Filing Info

  • Accession Number: 01044315
  • Record Type: Publication
  • Report/Paper Numbers: WA-RD 660.1
  • Contract Numbers: Agreement T2695, Task 95
  • Created Date: Mar 10 2007 11:42AM