Guardrail Deflection Analysis, Phase I: (2010-11) (405160-24)

Designers are often faced with having to design beam guardrail systems to accommodate a variety of allowable maximum deflections to fit specific site conditions. Tools for determining those deflections are limited, and it is time consuming to research crash test data to review work that is already conducted. With the wealth of information available through crash test reports and Federal Highway Administration (FHWA) acceptance letters, information can be categorized and tabulated into a table for use by designers for selecting appropriate beam guardrail for the desired maximum deflection. The research team reviewed full-scale crash test reports to tabulate guardrail deflection. These crash tests were performed at Texas Transportation Institute, Midwest Roadside Safety Facility, Southwest Research Institute, and other testing facilities. Acceptance letters issued by Federal Highway Administration were also reviewed. Deflection results for 53 different guardrail configuration are presented herein. Based on these literature reviews, the following guardrail systems are synthesized herein;

• 12 gauge W-beam guardrail,
• Thrie-beam guardrail,
• 13 gauge buffalo guardrail,
• Nested W-beam guardrail,
• W-beam guardrail for special placement need such as for placement on a slope, with simulated culvert applications, and with various flare rates.

The tabulated guardrail systems include related specifications regarding the rail height, post size, post material, post spacing, blockout, and test designation. The rail height is from the top of the rail to the ground level. These tables present the maximum permanent and dynamic deflection, and working width.