Barrier installations are warranted (or justified) only at highway locations where the consequence of an errant vehicle leaving the roadway is judged to be more hazardous than the impact with the barrier installation. A six degree-of-freedom mathematical model was found to be useful in describing dynamic behavior of a vehicle during impact. Predictions of vehicle and barrier behavior correlated with results obtained from full-scale crash tests. Crash conditions simulated with a computer were used to identify and evaluate vehicle static and dynamic as well as barrier parameters. Vehicle weight, yaw mass moment of inertia, and deformation constant were found to be significant.

This document presents a synthesis of current information and operating practices related to roadside safety and is developed in metric units. The roadside is defined as that area beyond the traveled way (driving lanes) and the shoulder (if any) of the roadway itself. The focus of this guide is on safety treatments that minimize the likelihood of serious injuries when a driver runs off the road. This guide replaces the 1989 AASHTO "Roadside Design Guide."

At head of title: National Cooperative Highway Research Program.

This roadside safety design package has been developed to satisfy a need for training in this area. It is hoped that all persons involved in the design, construction, operation, and maintenance of highways will become familiar with the concepts contained in the program. The concepts and practices discussed come from those contained in the AASHTO publication, "Highway Design and Operational Practices Related to Highway Safety". They are discussed in considerable depth in this program and should provide a good working knowledge of roadside safety design. Much of the program is oriented around freeways; however, the principles apply equally toward the lower order highway.

TRB's National Cooperative Highway Research Program (NCHRP) Report 663: Design of Roadside Barrier Systems Placed on MSE Retaining Walls explores a design procedure for roadside barrier systems mounted on the edge of a mechanically stabilized earth (MSE) wall. The procedures were developed following American Association of State Highway and Transportation Officials Load and Resistant Factor Design (LRFD) practices. Appendices A through H to NCHRP Report 663 are available online. Titles of Appendices A through H are as follows: Appendix A: Design of MSE Wall; Appendix B: State-of-Practice Survey; Appendix C: Detailed Drawing of MSE Wall for Bogie Test; Appendix D: Bogie Test MSE Wall Construction Procedure; Appendix E: Detailed Drawing of MSE Wall for TL-3 Test; Appendix F: TL-3 MSE Wall Construction Procedure; Appendix G: Crash Test Vehicle Properties and Information; Appendix H: Crash Test Sequential Photographs--