Validation of Origin-Destination Data from Bluetooth Re-Identification and Aerial Observation

Vehicle re-identification using Bluetooth (BT) signal data has emerged as an effective and economical means for collecting traffic data including Origin Destination (OD) information which is crucial for transportation planning. Direct vehicle tracking based on Time-Lapse Aerial Photography (TLAP) is also increasingly used for OD studies. Neither technique has previously been validated, so the objective of this study was to validate ODs generated using both techniques against a " ground-truth " OD. Traffic volume, Bluetooth-and TLAP-based OD data collected at an interchange in Madison, Wisconsin were used in this study. Significant variability (2.3% to 7.2%) in Bluetooth match rates were observed for the 12 OD pairs of the interchange. Uniproportional scaling of the sample Bluetooth OD (using average detection rate) resulted in poor fit to the true OD, but biproportional factoring (Fratar/Furness procedure) resulted in about 85% of the movements having GEH less than 5. Combining Bluetooth data from multiple days resulted in a better fit than using a single day's data. The analysis showed that Bluetooth can be used to obtain representative OD of an access-controlled network for planning applications. TLAP sample OD data was scaled using an origin-specific factor and resulted in reasonable fit to the true OD. Biproportional factoring resulted in a better fit with 100% of the movements having a GEH less than 5. Therefore, biproportional factoring is also recommended for TLAP data. INTRODUCTION Over the last few years, Bluetooth (BT) signal re-identification has emerged as a popular and economical option for several transportation applications including travel times, route choice, border crossing wait times, and Origin-Destination (OD) studies. In 2008, Wasson, Studevant and Bullock were the first to report using Bluetooth to track vehicles, pedestrians, and wait times at airport security lines (1). The University of Maryland's Center for Advanced Transportation Technology developed a portable Bluetooth monitoring system in 2008 (2). Although Bluetooth has been used for completing several OD studies, to date no research has validated its use for estimating OD matrices by comparing Bluetooth outputs with a true OD based on counts. Sun et al. presented a video based methodology for validating a Bluetooth based OD (3), but actual validation was not performed. Blogg et al. compared Bluetooth based OD to OD based on manual video tracking of licenses and automatic license plate recognition (ALPR) and found them to be similar (4). Conversely, Corradino Group compared Bluetooth with ALPR for an external OD study …