EVALUATION OF TRAFFIC CONTROL IMPROVEMENTS ON LOW VOLUME HIGHWAYS

THE EFFECTIVENESS WAS MEASURED OF TWO SPECIFIC TYPES OF OPERATIONAL IMPROVEMENT; OVERHEAD FLASHES AND TRAFFIC SIGNALS INSTALLED AT LOW VOLUME, HIGH SPEED RURAL INTERSECTIONS, IN REDUCING TRAFFIC ACCIDENTS ON LOW VOLUME, HIGH SPEED RURAL HIGHWAY INTERSECTIONS. A BEFORE AND AFTER STUDY APPROACH, ENCOMPASSING MINIMUM TIME FRAMES OF ONE YEAR PRIOR TO AND IMMEDIATELY AFTER INSTALLATION OF THE DEVICE, WAS UTILIZED. ACCIDENT EXPOSURE DURING THE TWO PERIODS WAS COMPARED ON THE BASIS OF EXPOSURE RATES, SEVERITY INDICES, AND EQUIVALENT PROPERTY DAMAGE ONLY (EPDO) ACCIDENTS AND RATES. THE EPDO RATE, RATHER THAN THE NORMALLY USED ACCIDENT RATE, WAS FOUND TO BE THE MOST RELIABLE AND SIGNIFICANT INDICATOR OF ACCIDENT CONSEQUENCES. THE STUDENT "T" TEST WAS SELECTED TO EVALUATE ANY DIFFERENCE IN EPDO RATES BETWEEN THE BEFORE AND AFTER PERIODS. IT WAS DETERMINED THAT THERE IS AN ASSOCIATION BETWEEN THE INSTALLATION OF FLASHING BEACONS AND A REDUCTION IN EPDO RATES. NO STATEMENT CAN BE MADE CONCERNING SIGNALS BECAUSE THE RESULTS OF THE ANALYSIS WERE NOT HIGHLY SIGNIFICANT. THE PERCENTAGE RATES OF CHANGES RELATING SIGNALS AND FLASHERS TO ACCIDENT TYPE, SEVERITY, TOTAL ACCIDENTS, AND EPDO ARE SUMMARIZED IN A TABLE. IN THE COMPARISON OF FLASHING BEACONS BEFORE AND AFTER, THE STATISTICAL ANALYSIS PROVED THAT THERE WAS A SIGNIFICANT REDUCTION IN EPDO RATES ON THE AGGREGATE SITES AND THE FOUR-LEG, THREE-LEG, AND CHANNELIZED INTERSECTIONS. THE EPDO RATE INCREASE IN THE AFTER PERIOD ON NON-CHANNELIZED INTERSECTIONS WAS NOT SIGNIFICANT. IN THE MULTIPLE VEHICLE ACCIDENT CONSEQUENCES, LEFT TURN ACCIDENTS APPEARED TO DECREASE IN THE AFTER PERIOD EXCEPT ON CHANNELIZED HIGHWAY INTERSECTIONS. REAR END COLLISIONS TENDED TO DECREASE AS DID CROSSING AND OTHER ACCIDENTS IN THE MULTIPLE VEHICLE CATEGORY. THE SEVERITY COMPARISON INDICATED A REDUCTION OR, NO CHANGE, IN THE FATAL GROUP AND A REDUCTION IN TYPE A (EXCEPT AT NON-CHANNELIZED INTERSECTIONS), TYPE B (NO CHANGE AT THREE-LEG INTERSECTIONS), AND TYPE C (NO CHANGE AT THREE-LEG AND NON- CHANNELIZED INTERSECTIONS). THE EPDO CATEGORY WAS MIXED WITH INCREASES IN FOUR-LEG AND NON-CHANNELIZED INTERSECTIONS AND REDUCTIONS IN THE OTHER CONSEQUENCES. THE SEVERITY INDEX FOR ALL GROUPS DECREASED EXCEPT AT NON-CHANNELIZED INTERSECTIONS.

• Supplemental Notes:
  • 94 Pp, 1 FiG, 14 TAB, 12 REF, 4 APP
• Corporate Authors:

  North Carolina State University, Raleigh

  Highway Research Program, P.O. Box 5993
  Raleigh, NC  United States  27607
• Authors:
  • Cribbins, P D
  • Bennett, J W
  • Walton, C M
• Publication Date: 1969-6

Subject/Index Terms

• TRT Terms: Before and after studies; Channelized intersections; Crash rates; Crash severity; Crash types; Flashing traffic signals; High speed ground transportation; High speed vehicles; Intersections; Loss and damage; Property; Rural highways; Speed; Traffic control; Traffic control devices; Traffic signals; Traffic volume
• Uncontrolled Terms: Low cost roads; Property damage
• Old TRIS Terms: Overhead traffic signals
• Subject Areas: Highways; Operations and Traffic Management; Railroads; Safety and Human Factors;

Filing Info

• Accession Number: 00221036
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 5 1970 12:00AM