ERIC Number: ED312438
Record Type: Non-Journal
Publication Date: 1988-Jul
Reference Count: N/A
Speed Variance and Its Influence on Accidents.
Garber, Nicholas J.; Gadirau, Ravi
A study was conducted to investigate the traffic engineering factors that influence speed variance and to determine to what extent speed variance affects accident rates. Detailed analyses were carried out to relate speed variance with posted speed limit, design speeds, and other traffic variables. The major factor identified was the difference between the design speed of the highway and the posted speed limit. It was determined that speed variance will be minimal if the posted speed limit is between 6 and 12 miles per hour lower than the design speed, and that outside this range, speed variance increases with increasing difference between the design speed and the posted speed limit. Other findings were that: (1) drivers tend to go at increasing speeds as roadway geometric characteristics improve, regardless of the posted speed limit; and (2) accident rates do not necessarily increase with increase in average speed but do increase with increase in speed variance. The results can be used to estimate changes in speed variance due to changes in traffic characteristics and, therefore, can provide traffic engineers with a means for controlling speed variance due minimize accidents. (Author/KC)
Descriptors: Motor Vehicles, Road Construction, Safety Education, Signs, Traffic Accidents, Traffic Control, Traffic Safety, Vehicular Traffic
AAA Foundation for Traffic Safety, 1730 M Street, N.W., Suite 401, Washington, DC 20036.
Publication Type: Reports - Research
Education Level: N/A
Authoring Institution: AAA Foundation for Traffic Safety, Washington, DC.