Evaluating the Accuracy of Speed and Volume Data Obtained via Traffic Detection and Monitoring Devices

Abstract

One of the most controversial topics facing traffic engineers, departments of transportation, and transportation agencies is using an appropriate device in collecting accurate traffic data without creating any negative influence on a traffic flow. Therefore, conducting a field evaluation of traffic data collection detectors become high-priority. This study was initiated to explore a proper device among three non-intrusive ITS sensors to collect a specific traffic parameter in comparison to the Pneumatic Road Tubes (PRTs). The three tested sensors were iCone, Radar Recorder, and Wavetronix SmartSensor HD. This study conducted a comparison of multiple traffic data collection sensors along on a rural two-lane road (US 24/40) with low traffic volume and a posted speed limit of 55 mph in both winter and spring conditions, in addition to some studies were conducted on iCone at different locations in summer. This thesis quantifies the difference in accuracy of the devices used for collecting speed and volume traffic data. Also, it identifies the difference in speed distribution due to the presence of tested devices, the accuracy and similarity between devices in gathering speed and/or counts data, and influences on driver behavior in addition to the usability of these devices. The results showed that the error in detected speeds and volumes for iCone and Radar Recorder in comparison with PRTs were 1.5 percent and 1.4 percent, respectively, while for the Wavetronix SmartSensor HD was 2.1 percent. The error in detected volumes for the iCone and Radar Recorder in comparison with the PRTs were 8.6 percent and 7.8 percent, respectively, while for the Wavetronix SmartSensor HD was same as PRTs detected. Regarding driver behavior towards deployed devices on the roadside, the largest reduction in speeds was observed when the Wavetronix SmartSensor HD was used. It was also observed that an iCone installation was easier than other devices and it fits to work zones because of its shape. Based on the results, to collect traffic volume data for each traffic lane separately, regardless of driver response, the Wavetronix SmartSensor HD is recommended. When collecting individual vehicle data is required, with taking into consideration the driver response, the Radar Recorder is recommended. As long as individual vehicle data are not required, the iCone could be a convenient option especially for short time data collection and more specifically at work zones.