THESIS ABSTRACT

Abstract

Road traffic crashes are a major safety concern on rural roads in Nepal, where challenging terrain, sharp curves, limited road width, step gradients, and limited roadside protection are causing an increase in the number and severity of crashes. The Government of Nepal has been adopting different safety measures, including W-beam crash barrier installation. This study assesses the perception of drivers and speed performance of crash barrier installation along the Chakchake–Bhingri road section in Pyuthan District. Driver’s perception survey on overall safety of W-beam barrier installation was analyzed using relative effectiveness index (REI), and result shows improved road safety, confidence, and alertness perception for drivers. The overall road safety (1-10 scale) of the study road section increased from 5.6 without a W-beam crash barrier to 7.1 with a W- beam Crash barrier. Vehicle speed was determined with and without W-beam crash barriers for two wheelers, light, and heavy vehicles. Descriptive analysis of speed data shows significant speed reduction for heavy vehicles and two wheelers, while an increase in the 85 th percentile speed for some sections indicates the risk-taking behavior or driver with a barrier. Multiple regression analysis shows that the presence of a crash barrier reduces vehicle speed by approximately 2.38 km/h (p < 0.001), after controlling for other variables. However, road geometry factors such as road width, curvature, and gradient exhibited stronger influences on speed variation. The qualitative approach includes validation of the driver’s perception and speed performance results with key informant interviews (KII), and quantitative findings were supported by KII. KII highlighted that the increased safety perception leads drivers to operate vehicles in safer environments, which ultimately helps in increased effectiveness due to barrier installation. The findings suggest W-beam crash barrier installation should be prioritized on narrow roads with sharp to medium curves based driver perception and speed performance of vehicles, where additional lane widening could further strengthen the outcome.

Keywords

Crash barrier, vehicle speed, road safety, relative effectiveness index, regression analysis, Key informant interview.