Barrier Deflection Characteristics of 31-inch W-Beam Guardrail Systems with 8-inch Blockouts (603481)

Problem Statement No. 2014-FL/70
Final Report:  Barrier Deflection Characteristics of 31-inch W-Beam Guardrail Systems

TTI Research Supervisor:
Dusty R. Arrington
Associate Transportation Researcher
Texas A&M Transportation Institute
3135 TAMU
College Station, Texas 77843-3135
(979) 845-4368
[email protected]
or  [email protected]
Pooled Fund Technical Representative:
John Mauthner, P.E.
Design Standards Manager
Florida Department of Transportation
605 Suwanne Street
Tallahassee, Florida 32399-0450
(850) 414-4334
[email protected]


The purpose of this research effort was to provide updated maximum deflection values based on simulations and crash test results for installations of 31-inch W-beam guardrail systems (SGR47). The research summarizes the results of computer simulations and crash tests to determine maximum deflections for new 31-inch W-beam guardrail systems with standard W6×8.5 strong posts with wood block-outs(SGR47) and varying post spacing (full-post spacing, half-post spacing, and quarter-post spacing) of both single and nested guardrail elements.

Phase I of the research was performed previously to gather the available crash test data on W-beam guardrail systems and is discussed under separate cover. Phase II of the research was focused on simulating additional 31-inch guardrail systems to broaden the range of system configurations for which deflection data is available. This phase fills in the gaps in crash test data by simulating useful configurations using BARRIERVII, a two-dimensional finite element analysis program. These simulations were used to predict the deflection characteristics of specific guardrail configurations. The resulting data was then combined with crash test data to update the American Association of State Highway and Transportation Officials (AASHTO) Roadside Design Guide barrier deflection guidance table.

The information compiled from this research provides design engineers with updated deflection values for various configurations of 31-inch W-beam guardrail under AASHTO Manual for Assessing Safety Hardware (MASH) impact conditions. These values can be used to determine an appropriate guardrail configuration to use when clearance to a hazard or obstruction behind the rail is less than the design deflection of standard 31-inch W-beam guardrail.

Strong Post Nested W-beam Guardrail

Post Spacing Impact Location Downstream of Upstream End Anchor (inches) Maximum Barrier Deflection (inches)
Full (CIP) 828 46
Half (CIP) 852 26
Quarter (CIP) 852 17