Bluetooth traffic monitoring was developed at the University of Maryland Center for Advanced Transportation Technology in 2008. Based on the point to point data transmission protocol commonly referred to as Bluetooth, the system logs the unique identifier, called the MAC identification number, at both an upstream and downstream location.  Similar to license plate matching, the system match MAC identifiers to obtain a sample of travel time.  The system has since been patented and commercialized, and is now used frequently as a standard tool for travel time measurement, and origin and destination studies.

website_bluetooth (pdf)