MAKING TWO-LANE ROADS SAFER

The Federal Highway Administration's Interactive Highway Safety Design Model (IHSDM) is a suite of software analysis tools for evaluating safety and operational effects of geometric design decisions on 2-lane rural highways. IHSDM provides highway project planners, designers, and reviewers in state and local departments of transportation and engineering consulting firms with a suite of safety evaluation tools to support these assessments. The suite includes five evaluation modules: policy review, crash prediction, design consistency, intersection review and traffic analysis. Each module provides different measures of the expected safety performance of an existing or proposed highway geometric design. This article gives an overview of the 2003 release of IHSDM, which highway project decision makers can use to check designs for conformance with design policy, estimate their expected safety performance, and diagnose potential safety and operational issues throughout the highway design process.