INVESTIGATION OF MEDIANS AND MEDIAN OPENINGS ON DIVIDED HIGHWAYS IN NORTH CAROLINA

ACCIDENT INFORMATION AND ROADWAY CHARACTERISTICS FOR EVERY SECTION OF MULTI-LANE DIVIDED HIGHWAY WITHOUT ACCESS CONTROL AND WITH NON-CROSSABLE MEDIANS WERE STUDIED TO DETERMINE THE OPTIMUM OPENING SPACING WITH SAFETY, ROADSIDE ACCESS, AND LEVEL OF SERVICE BEING STUDIED SIMULTANEOUSLY. THE ROADWAY CHARACTERISTICS CONSIDERED WERE MEDIAN WIDTH, SPEED LIMIT, ADT VOLUME, THE NUMBER OF SIGNALIZED INTERSECTIONS PER MILE WITH AND WITHOUT LEFT TURN STORAGE, THE NUMBER OF UNSIGNALIZED INTERSECTIONS PER MILE WITH AND WITHOUT LEFT TURN STORAGE, AND THE AMOUNT OF ROADSIDE INGRESS AND EGRESS PER MILE. THE EFFECT OF THESE CHARACTERISTICS ON THE ACCIDENT RATE AND LEVEL OF SERVICE WAS INVESTIGATED. DATA ARE STRATIFIED BY LOCATION TYPE AND ARE ANALYZED BY MULTIPLE REGRESSION TECHNIQUES. IT WAS DETERMINED IN THE DEVELOPMENT OF A PREDICTION EQUATION FOR ACCIDENTS THAT THE AVERAGE DAILY TRAFFIC VOLUME AND ROADSIDE ACCESS COMBINED WITH THE NUMBER AND TYPE OF MEDIAN OPENINGS ARE THE MOST IMPORTANT PREDICTORS OF ACCIDENT RATES. REAR-END COLLISIONS ACCOUNT FOR 33 PERCENT OF ALL ACCIDENTS ON FOUR-LANE, NON-ACCESS CONTROLLED HIGHWAYS, WITH UNSIGNALIZED AND SIGNALIZED INTERSECTIONS BEING THE MOST HAZARDOUS LOCATIONS, RESPECTIVELY. ACCIDENT RATES AND LEVEL OF SERVICE CAN BE PREDICTED FOR GIVEN SECTIONS OF EXISTING HIGHWAYS BY THE USE OF REGRESSION MODELS. THE FOLLOWING GENERAL CONCLUSIONS WERE REACHED' /1/ AS TRAFFIC VOLUME AND ROADSIDE DEVELOPMENT INCREASE, USAGE OF MEDIAN OPENINGS RAPIDLY BECOMES HAZARDOUS , AND /2/ AS ROADSIDE DEVELOPMENT INCREASES AND CROSSOVERS OF ANY TYPE ARE PERMITTED, ACCIDENTS WILL INCREASE. SEVERAL RECOMMENDATIONS ARE OFFERED AS GUIDES FOR FORMULATING POLICIES REGARDING /1/ MEDIAN PLACEMENT ON FUTURE FACILITIES , AND /2/ THE CLOSING OR ADDITION OF MEDIAN OPENINGS ON EXISTING FACILITIES.

• Supplemental Notes:
  • Hpr, 93 Pp, 1 FIG, 8 TAB, 11 APP
• Corporate Authors:

  North Carolina State University, Raleigh

  Raleigh, NC  United States  27695
• Authors:
  • Cribbins, P D
  • Horn, J W
  • Beeson, F V
  • TAYLOR, R D
• Publication Date: 1966-6

Subject/Index Terms

• TRT Terms: Average daily traffic; Crash rates; Crossovers; Design; Divided highways; Handling and storage; Hazards; Interchange ramps; Intersections; Left turns; Level of service; Median openings; Medians; Multilane highways; Optimization; Railroad grade crossings; Regression analysis; Regulatory signs; Roadside improvement; Spacing; Speed limits; Storage facilities; Traffic signals; Traffic volume; Width
• Old TRIS Terms: Freeway entrances and exits; Left turn only; Optimum design
• Subject Areas: Data and Information Technology; Design; Freight Transportation; Highways; Operations and Traffic Management; Railroads; Terminals and Facilities;

Filing Info

• Accession Number: 00224844
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Sep 3 1994 12:00AM