Least-cost design of highway geometry

In spite of being in existence for decades, the present practice of two-lan e horizontal curve design has several drawbacks. In consideration of the dr awbacks of the present design practice and based on expected total cost and expected change in total costs, models are developed for determining optim um degree of curvature for a given section of new or existing highway. A mo del is developed to accommodate the consistency and environmental constrain s that are critical in road construction in difficult terrain.