ACCIDENT ANALYSIS ON TWO-LANE ROADS

Abstract

The effects on traffic safety, as measured by accident rates, of pavement width radius of curve, gradient, sight distance, traffic volume, and design speed on curved section of two-lane highways are discussed in this report. There is a distinct tendency for accidents to decrease with increasing pavement width up to about 7.5m, and there is a negative relationship between radius of curve and accident rate. Gradients of up to about 6 percent have a relatively small effect on the accident rate, but a sharp increase in the accident rate is observed on grades of more than 6 percent. There exists a negative relationship between available sight distance and accident risk. An accident rate of 2.0 accidents per million vehicles - Km is proposed in literature as a breakpoint between levels of safety and unsafety. Accident data for last 10 years were collected at various sections of two lane intercity roads, from police FIR in Roorkee, Mangalore and Meerut. Traffic count and road condition data were collected from concerned PWD offices at Roorkee, Hardwar and Meerut. These data were analyzed statistically to see the effect of influencing parameter on accident rate. It was found that the monthly variation in accident rate in a year is very marginal. Among various types of vehicles, trucks/lorry are involved in maximum and bicycle in minimum number of accidents. Further, it was found that accident rate increases with increase in AADT, where as accidents per million vehicles Km-year (MVKY) decreases with increase in AADT. Accidents and injuries per MVKY decreased over the period 1992-2001 and no particular trend was found for fatality rate. 1.05 percent of total road accidents occur due to bad road condition only. Accident prediction models were developed for each road based on accidents per Km-year, AADT and road condition rating.