Route choice is often assessed with either a modeling technique or field observations. Field observations have historically used a variation of license plate matching. The proposed technique assesses route choice and travel time that uses an anonymous Bluetooth media access control (MAC) address sampling technique as a surrogate for license plate matching to assess route choice. The Bluetooth sampling technique was used to evaluate the impact of an unexpected bridge closure in northwest Indiana, including an assessment of the proportion of vehicles using each of four alternate routes. The Bluetooth technology also provided a means to collect travel time data for each alternate route; these observed travel times were also compared with travel time estimates obtained by route classification and link distance. In general, the route choice behavior was consistent with observed travel time estimates. The Bluetooth sampling technique is cost-effective to deploy, and although results are approximate, direct measurement of travel times and route choice is useful for public agencies to assess mobility and travel time reliability along alternate routes.

Typically, speed limits are reduced in work zones to safely accommodate construction activities and motorists on the roadway. This paper presents a methodology to evaluate the temporal and spatial effects of techniques designed to encourage compliance with work zone speed limits. The evaluations were performed over short and long segments within and adjacent to an Interstate construction work zone in suburban Indianapolis, Indiana, with the use of vehicle probe data. Space mean speed was measured by using 13 Bluetooth probe data acquisition stations, which provided a random sample of unique identifiers for approximately 11% of the passing vehicles. These space mean speed data were used to compute a series of comparisons between a day with no enforcement activity and a day with exceptionally high enforcement. During enforcement, the space mean speed decreased by approximately 5 mph throughout the 12.2-mi study segment. Within 30 min after the enforcement detail ended, however, space mean speeds increased, and there was no statistically significant residual impact on the space mean speed. Even at the absolute peak of enforcement, 75% of the probe vehicles exceeded the speed limit in all but one of the segments that had a posted speed limit of 45 mph. In addition, 25% of the probe vehicles exceeded the posted limit by more than 5 mph in all 45-mph segments during peak enforcement. The study is perhaps the largest ever conducted with respect to concurrent enforcement and extensive space mean measurement. The data represent an upper bound on the impact of enforcement activity on work zone speeds and should be of interest to public agencies as they consider compliance techniques.

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Travel time reliability (TTR) is considered a critical piece of information in highway performance evaluation. The L02 project from Strategic Highway Research Program 2 (SHRP2) has developed a holistic method using statistical probability functions of travel time as the TTR measure to build highway performance evaluation and monitoring systems. Compared with single-value reliability measures, the L02 measure is able to identify sources of unreliability and quantify their associated impacts. To validate the adaptability of L02 measure, TTR analysis on the I-15 freeway corridor in Salt Lake City, Utah using probe data has been conducted. The result is compared against output from the quadrant-based TTR measure that is currently used by the Utah Department of Transportation. Through cross-validation, it is determined that the two suites of measures demonstrate good consistency in relation to reliability assessment and unreliability source diagnoses. In addition, the study provides a method to calibrate the quadrant-based TTR measure, and new critical values were developed based on the cross-validation.

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