Travelers that used in-vehicle devices to alert themselves of freeway traffic congestion reportedly saved an average of 30 minutes each time they used the information to change their travel routines.
Experience with in-vehicle traveler information devices in Washington State
Made Public Date


Puget Sound
United States

An Analysis of the Puget Sound In-Vehicle Traffic Map Demonstration

Summary Information

This study tested the use of an in-vehicle traffic map device called TrafficGauge to determine the perceived and actual benefits of using in-vehicle freeway traffic congestion information in the Puget Sound region of Washington State. With assistance from the Washington State DOT (WSDOT) the University of Washington recruited participants from around the region to test the in-vehicle devices. Participant usage was monitored for a period of six months and customer satisfaction survey data were collected from November 2007 to May 2008 to evaluate user experience, and collect information on frequency of use and benefits gained.


An initial entry survey was used to collect baseline and demographic data, a daily survey was used to monitor day-to-day experiences, and an exit survey was used to evaluate overall impressions at the conclusion of the field test. A total of 2,215 participants completed an initial entry survey and 1,934 participants provided feedback during and after field testing.

In addition to evaluating user experience, network performance data were collected in Bellevue, Washington to examine if the congestion information provided had any noticeable impacts on alternative route usage during unusually congested conditions on freeways. The analysis looked for correlations between performance on three freeways and the four arterials.


  • On average, the travelers surveyed indicated that they changed their travel routine once every 4.2 times that they used the TrafficGauge device.
  • Travelers reported that they saved an average of 30 minutes in travel time when they decided to change their travel routines based on the information provided.

The analysis of corridor performance confirmed that many travelers diverted from the freeways and used alternate routes based on the information they received from the device and the freeway conditions observed while en-route. Researchers noted, however, that even with modest levels of diversion from the freeways there was a noticeable increase in arterial congestion, and when this arterial congestion was visible from the freeway it discouraged further diversions.

An Analysis of the Puget Sound In-Vehicle Traffic Map Demonstration

An Analysis of the Puget Sound In-Vehicle Traffic Map Demonstration
Publication Sort Date
Briglia, Peter M.,
Washington State DOT

(Our website has many links to other organizations. While we offer these electronic linkages for your convenience in accessing transportation-related information, please be aware that when you exit our website, the privacy and accessibility policies stated on our website may not be the same as that on other websites.)

Application Taxonomy

Goal Areas
Deployment Locations