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

April 2010
Puget Sound,Washington,United States

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.

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

Author: Briglia, Peter M.,

Published By: Washington State DOT

Prepared by the University of Washington for the Washington State DOT

Source Date: April 2010

Other Reference Number: Report No. WA-RD 737.1



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Benefit ID: 2012-00812