The report presents papers which evaluate the safety cost-effectiveness of geometric design standards and also recommend minimum standards for resurfacing, restoration and rehabilitation (RRR) projects. Such projects may include resurfacing, minor widening of lanes and shoulders, minor alterations to vertical and horizontal alignment, bridge improvements and the removal of roadside shoulders. The papers are presented in the following sections: 1 - geometric design standards for resurfacing, restoration and rehabilitation projects: background and issues; 2 - state and local procedures for selection, design and construction of highway improvement projects; 3 - relationships between safety and geometric design; 4 - relationships between highway costs and geometric design; 5 - safety cost effectiveness of geometric design standards; 6 - tort liability and geometric design; and 7 - findings and recommended design practices for resurfacing, restoration and rehabilitation projects. Appendices contain design details of the following - summary comparison of non-freeway geometric design standards and guidelines; case study state and local RRR programs; summary of detailed safety relationships; relationships between accidents and horizontal curvature; relationship between accidents and sight distance at crest vertical curves; relationship between accidents and specific roadside features; physical and operational features affecting safety at intersections; highway accidents on the federal-aid system; initial cost to flatten highway curves; relationship between cost per accident eliminated and benefit-cost ratio approaches; effects of lane and shoulder widths on travel time; alternative lane and shoulder width standards used in system-level analyses.
Samenvatting