Title: Assessing the accuracy and reliability of freeway traffic monitoring stations using GPS probe vehicle speed data

Authors: Piyali Chaudhuri, Aleksandar Stevanovic, Peter Martin

Addresses: Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Dr Rm 1650, Salt Lake City, UT 84112-0561, USA. ' Department of Civil, Environmental and Geomatics Engineering, Florida Atlantic University, 777 Glades Rd. Bldg. 36, Rm. 225, Boca Raton, Florida 33431, USA. ' Department of Civil and Environmental Engineering, University of Utah, 122 South Central Campus Dr Rm 104, Salt Lake City, UT 84112-0561, USA

Abstract: Freeway performance measures are extracted from Traffic Monitoring Stations (TMS) which gather traffic volume and speed data. Reported freeway speeds are usually aggregated over periods of 20 or 30-second or 1, 5, or 15-minute by traffic agencies. This paper examines the accuracy and reliability of reported TMS detector speeds. The study compares speeds collected by GPS-equipped probe vehicles with aggregated detector speeds. The paper evaluates how various aggregation intervals impact accuracy and reliability of TMS detector speeds and determines the optimal aggregation interval. Results indicate that shorter aggregation intervals are appropriate for high variability traffic conditions during peak periods.

Keywords: TMSs; traffic monitoring stations; loop detectors; freeway speeds; probe vehicle speed data; accuracy; reliability; optimal data aggregation; aggregation intervals; traffic volume; GPS; global positioning system; motorway speeds.

DOI: 10.1504/WRITR.2011.041717

World Review of Intermodal Transportation Research, 2011 Vol.3 No.4, pp.338 - 352

Received: 22 Sep 2010
Accepted: 16 Mar 2011
Published online: 01 Aug 2011 *

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