Abstract
A 30 km portion of a mountain road that lies along A1-Baha descent suffers from frequent rock failures, mainly in rainy seasons. Failures in both natural and man-made rock slopes are formed mainly of wedge, planar, and toppling failures, and rockfalls. Slope stability analyses were performed to identify the stability/instability zones. Probability analyses of casualties along the road have been performed using the rock slopes factor of safety and probability of failure analyses. Areas of high probability of failure have high probabilities of casualties. The probability of a vehicle running into a landslide is calculated at rush hours. The results indicate that an increase of support measures will decrease the likelihood of failure and casualties in the areas that are prone to failure. The highest risk sections along the road are those characterized by the lowest factor of safety, and lowest support measures, particularly at rush hours on rainy days.