Distance from pavement edge: The three edges should be flush with the pavement.Guardrail height: The middle of the steel should be 610 mm (24″) above the pavement.Dimensions: 508 mm high by 78 mm wide (20″ x 3″).Here are the specifications for Thrie beam: It is used on bridges and other, generally specialty, applications. Thrie beam is similar to flex beam, but with three leading edges instead of two. The standard specification is AASHTO M180. you’re not likely to get anything else very cheaply). Most state DOT’s have standards for both, and the manufacturers will build them all to the standard (i.e. Bolts are galvanized to ASTM A153.Įnd sections can be either turn down or a crash absorption barrier. Galvanizing: 600 g/m 2 (56 g/ft 2) according to ASTM A924 or A123.Steel Posts: Either 110 x 150 x 4.5 mm (4.3″ x 5.9″ x 0.18″) cold formed C-sections or W150 x 13 (W6x8.5) hot rolled structural shapes conforming to ASTM A36 or A588.Wooden Posts: Either construction grade Southern Pine or Douglas Fir, pressure treated, 203 mm x 152 mm (8″ x 6″).Distance from pavement edge: The two edges should be flush with the pavement.top of guardrail 31 inches above pavement). Guardrail height: The middle of the steel (bolts) should be 550 mm (25 inches) above the pavement edge (i.e.Significant research has gone into the placement of flex beam, and the following are the standard specifications: It consists of a w-shaped piece of steel with either wooden or steel posts. There are three types of guard rail in primary use today.Īlso called W-beam, flex beam is the cheapest and easiest to install, and thus the most popular guard rail in use today. Summary Report of 2021 MASH Virtual Roundtablesįor more information on Guardrail Inspection, Maintenance, and Installation Information, please contact the Office of Safety, Aimee Zhang ( 20.Guard rail absorbs the impact of out-of-control vehicles while guiding the vehicle to safer stops.NCHRP Roadside Hardware Replacement Analysis: User Guide.Florida Department of Transportation In-Service Performance Evaluations (ISPE) web page.FHWA Pilot ISPE Guardrail End Treatmentįor information on ISPE pilot, contact Ana Maria Eigen ( ISPE National Cooperative Highway Research Program Study: NCHRP 22-33 Multi-State In-Service Performance Evaluations of Roadside Safety Hardware.FHWA memo on In-Service Performance Evaluation (ISPE).AASHTO’s MASH Hardware 2nd Edition, 2016, Chapter 7 – In-Service Performance Evaluation.Texas A&M: Developing an In-Service Performance Evaluation (ISPE) for Roadside Safety Features in Texas.Transportation Research Board (TRB) Special Report 323: In-Service Performance Evaluation of Guardrail End Treatment.TRB's National Cooperative Highway Research Program (NCHRP) Report 490: In-Service Performance of Traffic Barriers.In-Service Performance Evaluation (ISPE) ISPE Resources and Guidance Roadside Safety Hardware: The Last Line of Defense (Fact Sheet).Letter from Tennessee Department of Transportation on X-LITE end terminal.FHWA memo on Information on X-LITE Guardrail Terminals.Report to Congress: Roadside Safety Hardware Identification Methods.Guardrail 101 (Purpose, Function, and Crashworthiness of Guardrails).Federal Highway Administration (FHWA) memos on guardrail installation and maintenance.American Association of State Highway and transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH). Guardrail Inspection, Maintenance, and Installation Information Guidance and Memoranda
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