Abstract:
THE CONGESTION INDEX IS DEFINED AS A MATHEMATICAL RATING OF HIGHWAY CAPACITY DERIVED FROM THE RATIO OF EXISTING DESIGN HOUR TRAFFIC VOLUMES TO THE PRACTICAL HOURLY CAPACITY OF A RURAL HIGHWAY SYSTEM. THE DEVELOPMENT OF THE CONGESTION INDEX REQUIRES THE FOLLOWING ITEMS OF BASIC DATA: (1) FAIRLY EXACT INFORMATION CONCERNING THE RELATIONSHIP OF THE 30TH HIGHEST HOUR IN THE YEAR TO THE ANNUAL DAILY AVERAGE TRAFFIC FOR A HIGHWAY SYSTEM, (2) COMPLETE DATA ON CONTINUOUS RESTRICTED SIGHTS, AND (3) DETAILED INFORMATION AS TO THE GEOMETRIC DESIGN FEATURES OF THE COMPLETE RURAL HIGHWAY SYSTEM. AN INDEX PROVIDES A MEANS OF RELATING RURAL HIGHWAY CONGESTION TO ACCIDENT RATE. ALSO, THE INDEX IS VALUABLE AS A GUIDE IN THE PROGRAMMING OF PROJECTS FOR IMPROVEMENT. A LOW CONGESTION RATING INDICATES SATISFACTORY GEOMETRIC DESIGN. IF IMPROVEMENTS ARE REQUIRED ON ROUTES OF THIS CHARACTER, THEY ARE DICTATED BY OTHER FACTORS. THE LOW CONGESTION INDEX SHOULD BE VALUABLE IN PREVENTING OVERDESIGN. THOSE SECTIONS OF A RURAL HIGHWAY SYSTEM SHOWING A HIGH CONGESTION INDEX MUST, IN THEIR REDESIGN, PROVIDE ADDITIONAL TRAFFIC CARRYING CAPACITY. THE EXTENT TO WHICH A NEW DESIGN MUST PROVIDE SUCH CAPACITY CAN BE ACCURATELY MEASURED THROUGH THE APPLICATION OF THE PRINCIPLES INVOLVED IN THE CALCULATION OF A CONGESTION INDEX. /AUTHOR/
Supplemental Notes:
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