Interchange accident exposure

SAFETY IS ONE OF THE MOST EMPHASIZED FEATURES OF HIGHWAY TRANSPORTATION TODAY. ITS OVERALL IMPORTANCE IS STRIKINGLY UNDERLINED BY THE SHOCKING STATISTICS OF TRAFFIC FATALITIES AND ACCIDENTS. THE ECONOMIC LOSSES INVOLVED ARE TREMENDOUS. THE ROLE OF GEOMETRIC HIGHWAY DESIGN AS A CONTRIBUTING CAUSE OF ACCIDENTS HAS LONG BEEN RECOGNIZED. ACCIDENT ANALYSIS HAS BEEN EXTENSIVELY USED TO EVALUATE DESIGN. AN ACCUMULATION OF ACCIDENTS AT A SPECIFIC POINT ON A HIGHWAY IS EVIDENCE OF A FAULT WHICH IS RELATED IN SOME WAY TO THAT LOCATION. IT IS LIKELY THAT A CHANGE IN THE DESIGN COULD REDUCE THE ACCIDENT SUSCEPTIBILITY. EVALUATION PROCEDURES RANGE FROM A MERE ACCUMULATION OF ACCIDENT REPORTS ON AN ACCIDENT SPOT MAP TO A RATHER DETAILED GRAPHIC PRESENTATION ON LARGE-SCALE SKETCHES OF INTERSECTIONS OR SECTIONS OF HIGHWAY. FURTHER, THERE ARE THE WELL-KNOWN STATISTICAL EVALUATIONS, GIVING THE ACCIDENT OR FATALITY RATE PER VEHICLE-MILE OF TRAVEL. FOR INTERSECTIONS, THE CONVENTIONAL STATISTICS ARE RATHER MISLEADING BECAUSE THE EXPOSURE TO ACCIDENT IS NOT PROPORTIONAL TO THE DISTANCE TRAVELED. THE EXPOSURE RATE AT INTERCHANGES IS DEMONSTRATED AS AN EXAMPLE AND COMPARED TO ACTUAL ACCIDENT EXPERIENCES AT SEVERAL LOCATIONS. A QUALITATIVE ANALYSIS OF ACCIDENTS AT THESE INTERCHANGES IS ALSO PRESENTED. /AUTHOR/