This report provides guidance on selecting the appropriate barrier performance level for the installation of longitudinal barriers. The report presents performance-level selection guidelines to help designers determine the most appropriate guardrail test level for any route. Further, sitespecific guidelines not only identify what guardrail test level should be incorporated but also can be used to determine when guardrail use is not cost beneficial. Supplemental procedures for identifying appropriate guardrail test levels have also been developed. These procedures expand the applicability of the guardrail selection guidelines to many unusual hazards that cannot be included in development of general procedures. The report will be of particular interest to designers with responsibility for designing roadside safety features. The following appendices to NCHRP Report 638 are only available online: Appendix A, Guardrail Use Guidelines for Benefit/Cost = 2 (at: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_638appendixA.pdf); Appendix B, Guardrail Use Guidelines for Benefit/Cost = 3 (at: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_638appendixB.pdf); Appendix C, Guardrail Use Guidelines for Benefit/Cost = 4 (at: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_638appendixC.pdf); Appendix D, Guardrail Use Guidelines for Benefit/Cost = 1 (at: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_638appendixD.pdf). (Author/publisher)
Abstract