Use of Automatic Position Reporting System Data for Enhancing Transportation Planning Operations

Highway speed and travel times are generally the standard for evaluating highway network performance. Yet these data are often costly or difficult to obtain. As such, recent research has focused on exploiting new technologies (e.g., cell phones) as cost-effective sources of speed and travel time information. Consistent with this work, a new source of data and an acquisition approach that provides both vehicle speed and travel time measurements from ad hoc probe vehicles at modest cost are presented. In this system, probe vehicles collect Global Positioning System speed, heading, and position data and transmit them over amateur radio frequencies. Frequencies are monitored by personal computers, which are used to receive and process the probe data. System output consists of records containing traveler location, speed, and the time at which data were transmitted. Moreover, these data are managed and maintained as layers of points in a geographic information system and lend themselves to use in several applications. Contrasted with the system described, most traditional speed measurement systems (e.g., loop sensors) are restricted to collecting data at fixed points along major highways where sensors are installed. However, probe data facilitate regional analysis since acquiring information from probe vehicles does not depend on fixed observation points. Some of these applications and advantages of the data are discussed, and a detailed comparison of speed data retrieved from the presented probe system and data collected by traffic loop sensors is provided. The analysis demonstrates that the described probe vehicle system is an effective transportation data source.