A real-time travel time prediction system (TIPS) was evaluated in a construction work zone. TIPS includes changeable message signs (CMSs) displaying the travel time and distance to the end of the work zone to motorists. The travel times displayed by these CMSs are computed by an intelligent traffic algorithm and travel-time estimation model of the TIPS software, which takes input from strategically placed microwave radar sensors that detect the vehicle traffic on each lane of the freeway. Besides the CMSs and the radar sensors, the TIPS system includes the computer and microcontroller computing the travel times, 220 MHz radios for transmitting data from the sensors to the computer and from the computer to the CMSs, and trailers with solar panels and batteries to power the radar sensors, CMSs, and radios. The evaluation included two parts, the first part included an accuracy analysis between the predicted and actual recorded travel times, reported separately, and the second part included a survey of the motoring public regarding the acceptance of this system, reported here. Three crews driving independently of each other in the traffic stream recorded predicted and actual travel times at three CMSs to the end of the work zone for 12 hours each day for three consecutive days, resulting in 119 trial runs. The data recorder in each crew also recorded the license plate numbers of private non-commercial vehicles with Ohio license plates in the traffic stream. A total of 3177 different license plate numbers were recorded and a questionnaire was sent to each one by the Ohio Department of Transportation. A total of 660 completed surveys were returned and analyzed. About half (48%) of respondents were frequent users who drove through the work zone almost every day or more frequently. Survey responses indicated that the motoring public does perceive a certain inaccuracy in the travel times. However almost 97% of surveyed motorists felt that a system like TIPS providing real-time travel time information in advance of work zones and in advance of open exit ramps is either outright helpful or maybe helpful. In summary we may conclude that in the eyes of the motoring public the real-time TIPS system represents a definite improvement over any static non-real-time display system.
Publisher: Transportation Research Board
Publication Date: January 13-17, 2002
Full Text URL: Link to URL
Publication Types: Books, Reports, Papers, and Research Articles
Topics: Changeable Message Signs; Driver Perception; Intelligent Transportation Systems; Mathematical Models; Surveys; Traffic Control Devices; Travel Time