SPONSOR: Oregon Department of Transportation

BUDGET: $39,775

ABSTRACT: The Oregon Department of Transportation (ODOT) maintains an extensive freeway surveillance, management and traveler information system in the Portland metropolitan area. The statewide advanced traveler information system (www.tripcheck.com) provides traveler information across the state. The Oregon Department of Transportation's (ODOT) advanced traffic management system (ATMS) in the Portland metropolitan area is capable of computing estimated travel times for key freeway segments. The estimated travel times are currently relayed to travelers using variable message signs (VMS) located at key locations along the metro freeways. At this time, ODOT is considering reporting computed travel times on additional dynamic signs as well as disseminating travel times using other mechanisms such as the 511 phone system and the TripCheck web site. Prior to investing additional resources towards expanding the dissemination of travel times to Portland travelers, ODOT expressed interest in researching and understanding the accuracy of the current travel time calculations. Travel time estimations created by real-time processing of freeway loop detector data have been compared with travel times recorded by probe vehicles simultaneously driving on predetermined freeway routes. In general, the statistical analysis revealed that the travel time predictions by the ATMS perform very well. Only some locations did not result in statistically valid results suggesting that the calculated travel times were the same as the probe vehicle times. One target result of this project was some recommendations of those locations where additional detectors would improve travel time predictions. A methodology was followed that resulted in identifying seven locations that would likely have a significant impact on improving travel time predictions.

PRODUCTS:

journal Monsere, C., Breakstone, A., Bertini, R.L., Deeter, D. and McGill, G., "Validating Dynamic Message Sign Freeway Travel Time Messages Using Ground Truth Geospatial Data." Transportation Research Record: Journal of the Transportation Research Board, No. 1959, Transportation Research Board of the National Academies, Washington, D.C., 2006, pp. 19

report Deeter. D., C. Monsere, A. Breakstone, R.L. Bertini, "Evaluation of Freeway Travel Time Estimates: Final Report." Oregon Department of Transportation, Salem, Oregon. August 2005

conferenceproceedings Breakstone, A., "Using Ground Truth Geospatial Data to Validate Advanced Traveler Information Systems Freeway Travel Time Messages." Insitute of Transportation Engineers, District 6 Meeting , Kallispell, M., July 13 2005.