This paper describes how the safety of highway travel poses an intricate challenge to transportation engineers in Florida and other states as well.One of the challenges that need to be addressed is the accuracy of the crash data. Accurate data are essential and start with location. In the current practice, police officers estimate the distance of the crash location from a reference point such as the intersection, bridge, etc. The implementation of the Global Positioning System (GPS) in identifying the location using geographical coordinates that can be inputted in Geographic Information Systems (GIS) software for analysis would eliminate the errors caused by the estimation of the crash location. A study of accuracy of GPS for crash location was conducted. Several concerns regarding the use of GPS suchas problems in attaining satellite signals, time taken to lock satellites, problems in maintaining a lock on satellites, and accuracy in locating crashes were studied. A comparison of the accuracy of GPS units used for this study and those used for a similar purpose (crash location) three yearsago indicate a significant improvement for GPS units of the comparable cost margins. The results also indicate that the time taken to get a stable reading (time to lock satellites) has significantly decreased in the past few years. While the study that conducted done in Iowa, Washington state and Wisconsin in year 1998 reported the average satellite locking time of 8minutes. The study that was conducted in Alabama in year 2000 reported 3 minutes satellite locking time. In this study the average locking time of 1 minute and 49 seconds was observed. The average accuracies of 14.17 feetand 12.47 feet for Magellan Meridian and Garmin 76S units were obtained while Pharos and Trimble Geoexplorer units were found to have average accuracies of 18.77 feet and 5.58 feet respectively.
Samenvatting