Exploration of Rural Road Safety on Basis of Average Accident and Road Geometry: A Case study of Rural Road Kaski, Nepal

Abstract

Road geometric design in an inappropriate manner leads to road traffic accident which is major aspect to be consider regarding to safety. To ensure safety hazardous location must be identified on basis of accident regarding to road geometric elements. The basic purpose of this research is to examine the critical aspect between road geometric design and traffic safety in the rural mountainous terrain of Kaski, Nepal. Basically, the study aims to identify geometric elements which contribute to accident frequency and quantify their relationship through well calibrated mathematical models.This research assist to develop a framework for identifying design inconsistencies which lead to loss of property and life. This is a case study related to Methlang- Gyarjati rural road where three test curves are selected to collect necessary primary data using mobile sensors and standard survey equipment. Test-retest was conducted to ensure data integrity. The research utilizes a predetermined linear model (Y=0.03X+0.54) to estimate average accident numbers based on operating speed (V85) due to lack of consistent historical accident records. The sensitivity of each geometric predictor are establish through statistical analysis using General Linear regression. The findings reveal that shoulder width (Sw) is the most significant predictor of safety, explaining approximately 63% to 65% of the variability in infrastructure-estimated baseline accident risk rather than curve length and radius which fail to meet driver workload demands thus indicating geometric inconsistencies in the study section. The model was formulated as Yav=1.9084-0.4543Sw which mathematically elaborate significant decrease in estimated accident frequency with increase in shoulder width. Thus, it can be said that rural road accidents are tied to geometric deficiencies rather than random factors. The widening of shoulders to at least 1.0m to 1.5m at curve sections must be prioritize which is very sensitive in reducing long term risk. Thus, model develop herein play a vital role for maintaining geometric consistencies, safety audits and hence prevent huge loss of life and property.