Safety and cost-effectiveness of clear zones in Iran

Abstract

This paper examines different clear-zone improvement alternatives in rock cuts, and compares the likely effect on safety and construction costs. Where a roadway passes through rock cuts, the construction cost of providing the clear zone is very high. This paper is based on research that demonstrates a method for selecting the appropriate clear zone in rural two-lane highways in Iran based on the site and traffic conditions expected at the site. A method is described for determining the rock-cut width that best balances the cost of construction with the improvements in safety that would result from a wider clear zone in the rock cut. The objective of this study is to quantify the societal cost of rock-face accidents, so that the costs and benefits associated with different clear-zone policies can be explicitly addressed during the preliminary design process. This study shows that the need for extra clear-zone width in steep and bendy routes (specially with external curves of less than 195 m radius) is more...