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Road safety has emerged as a global priority due to the multifaceted consequences of road traffic accidents (RTAs) in modern society. The study is focused on the development of an accident prediction model (APM) and identifying the influence of geometric factors on road safety. The study section of the highway was divided into 190 identical segments based on geometric characteristics. Eight models have been developed for establishing the relationship between crash numbers and respective parameters. The significance of the models has been validated by the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). The study unveils that the shoulder and lane width, numbers, and radius of the horizontal curve significantly influence RTAs. However, the gradient and shoulder type have less impact on road accident frequency. The research recommendations for the improvement of safety are increasing the radius of the curves, lane, and shoulder width. Similarly, the study suggests the reduction of the number of horizontal curves for the reduction of crash frequency.

A pavement is considered a multi-layer system that distributes the vehicular load over a large area and transfers it to the foundation. Flexible pavement is mainly deteriorated due to the failure of its layer as well as the subgrade soil. Resisting the vehicular load requires the appropriate thickness of the sub-base and base with optimization of cost. This study aims to find the effect of the cement-treated base on thickness, unit cost, and life cycle cost. Design traffic was estimated for 15 years design period with an annual traffic growth rate of 5% for the Pathlaiya-Nijgadh Section of the East-West Highway of Nepal. The thickness of the granular base and the cement-treated base was 500 mm and 357.43 mm for design traffic of 34.86 million standard axles (msa) and the total pavement thickness for design traffic of 34.86 msa was 590 mm and 457.43 mm respectively. The comparison of cost estimates for the base course revealed that there was a 5.63% reduction in the per km cost of the cement-treated base as compared to the granular base. The cement-treated base seems to be a viable alternative to the base course for road construction as compared to the granular base. The pavement maintenance using a Cement-Treated Base (CTB) was 47.31% more economical than pavement maintenance using a granular base course. The total cost including initial investment and the cost of the maintenance of the pavement construction using CTB was 24.39% lower than that of the granular base.

Rutting and fatigue are the most common pavement distresses that are caused due to overloading, subgrade strength, and poor construction quality. The strength of the pavement layer can be improved by the construction of cement-treated layers. This study suggested that the cement-treated base is the effective modification technique for a granular base course by evaluating the unconfined compressive strength, and modulus of rupture. The unconfined compressive strength revealed that a cement-treated base is an effective treatment for the improvement of strength. Similarly, flexural strength indicated that a cement-treated base is an effective method to reduce the fatigue damage of the base course, and 5% cement content is sufficient to resist crack formation on the base course. 5.34% cement content in CTB developed a stiff mix with a stronger ability towards applied load dispersion that can resists deformation. In the meantime, unconfined compressive strength, modulus of rupture, and modulus of elasticity obtained at 5.34% cement content on a cement-treated base satisfied the minimum requirement as set by the Department of Roads, Government of Nepal.