STUDIES OF: (A) TRAFFIC CONTROL CRITERIA FOR WIND AND VISIBILITY, AND (B) CAPACITY OF THE NEW STANDARD-PLAN SNOW FENCE
This report is composed of three Wyoming based studies: (1) Visibility study - to develop visual range criteria for traffic control during blowing snow conditions; (2) Wind study - to determine the relationship between wind speed and accident frequency; (3) Characteristics of the drifts behind the new standard-plan fences at saturation to determine the capacity and drift configuration of the new fences being used. The following methods were employed, respectively: (1) For all drifting events, averages and minimum visual range were determined over all 10-minute intervals having a minimum visual range greater than and an average visual range equal to or greater than 1200 feet; (2) Wind related accidents from October 1, 1971 - April 1, 1973 were reviews for concurrent average wind speed and range for the hour of the accident to derive a frequency distribution, a relationship was determined between the average wind speed and the maximum gust, and then these values were determined for the first ten minutes of each hour, over an 8-hour period centered about accident time; (3) Snow depths were measured behind all saturated fences. Respectively, the results were as follows: (1) The visibility results are subjective, with the relationship between the minimum visual range and average visual range approximated by the equation V minimum equals 98 plus 0.68 V average, where units are feet and the correlation coefficient r equals 0.91; (2) Of the 89 wind-related accidents reported, 26 occurred within a 5 mile distance of the study site and were used in this analysis, and the frequency distribution shows 46 percent of the accidents to have occurred at average wind speeds of 30 to 39 miles per hour; (3) Capacities of the 6, 8, 10 and 12 feet fences are 310, 560, 900 and 1300 cubic feet, respectively. The conclusions were that: Traffic control regulations should be put into effect for average wind speeds in the 30's as well; Visibility recommendations must be considered tentative; There is reason to believe that the exceptional snow depths and capacity behind the new fences are due to the 15 degree inclination to leeward, in combination with the horizontal slats. /SRIS/
- Sponsored by the Wyoming State Highway Department.
Rocky Mountain Forest & Range Experiment StationColorado State University, 240 West Prospect Street
Fort Collins, CO United States 80521
- Tayler, R D
- Publication Date: 1973-9
- Features: Figures; Tables;
- Pagination: 12 p.
- TRT Terms: Crash rates; Drift; Snow; Snow fences; Traffic control; Velocity; Visibility; Wind
- Old TRIS Terms: Wind velocity
- Subject Areas: Highways; Maintenance and Preservation; Operations and Traffic Management;
- Accession Number: 00127425
- Record Type: Publication
- Source Agency: National Safety Council Safety Research Info Serv
- Report/Paper Numbers: Final Rpt.
- Contract Numbers: 16-311-CA
- Files: TRIS
- Created Date: Mar 29 1976 12:00AM