The research documented in this report was conducted as part of the Federal Highway Administration’s (FHWA) Evaluation of Low-Cost Safety Improvements Pooled Fund Study (ELCSI-PFS). FHWA established this PFS in 2005 to conduct research on the effectiveness of the safety improvements identified by the National Cooperative Highway Research Program Report 500 Guides as part of the implementation of the American Association of State Highway and Transportation Officials (AASHTO) Strategic Highway Safety Plan. The ELCSI-PFS studies provide a crash modification factor and benefit–cost (B/C) economic analysis for each of the targeted safety strategies identified as priorities by the pooled fund member States.
 

This study evaluates the safety effectiveness of horizontal curve realignment by increasing the radius of curved roadway segments on two-lane rural roads. One objective of this strategy is to reduce lane departure crashes, especially run-off-road crashes. The evaluation results showed substantial and significant reduction in crashes (total, injury and fatal crashes, run-off-road, and fixed object crashes, dark crashes, and wet-road crashes). The economic analysis revealed that increasing the radius of a horizontally curved roadway segment on two-lane, rural roads is a cost-effective safety improvement for reducing all types of crashes. This document is intended for safety engineers, highway designers, planners, and practitioners at State and local agencies involved with AASHTO Strategic Highway Safety Plan implementation.