The Georgia DOT Intelligent Transportation System, known as NaviGAtor, covers 140 freeway miles in the Atlanta metropolitan area. The NaviGAtor system includes a traffic management center (TMC), freeway management components, advanced traveler information systems, and an incident management program. TMC operators use vehicle detectors, closed circuit television (CCTV) cameras, dynamic message signs (DMS), and ramp meters to collect traffic data and manage incidents. When TMC operators identify an incident, they dispatch a Highway Emergency Response Operator (HERO) to provide motorist assistance or traffic control, and disseminate traveler information via DMS, the NaviGAtor web site (www.georgia-navigator.com), and a telephone information service (*DOT or 404-635-8000).
The benefits of the NaviGAtor incident management program were determined during a before-and-after study that analyzed twelve months of data (i.e., May 2003 to April 2004) from incident logs. The "before" conditions were estimated by analyzing incident information when a HERO could not respond, analyzing incidents that occurred outside of the NaviGAtor coverage area, and using public safety dispatch logs and personnel surveys to predict incident timelines when no NaviGAtor resources were employed. By comparing "before" conditions with "after" conditions when NaviGAtor incident management strategies were utilized, the benefits were determined in four areas: safety, mobility, energy and environment, and productivity.
The program resulted in an average 46-minute reduction in incident duration time and reduced incident delay by 7.25 million vehicle-hours. The NaviGAtor incident management program reduced the average incident duration time from 67 minutes to 21 minutes or by 69 percent. There were an estimated 13,544,000 vehicle-hours of delay before the program was implemented and only 6,290,000 vehicle-hours of delay after NaviGAtor. This amounts to a 54 percent reduction in delay.