MASH TL2 31-inch W-Beam Guardrail (602921)

MASH Problem Statement No. 2014 MN/WV/FHWA-61

Final Report:  Test Report No. 602921-1: MASH Test 2-11 of the 31-inch W-Beam Guardrail with 12.5-ft Post Spacing

TTI Research Supervisor:
Nauman Sheikh, P.E.
Associate Research Engineer
Texas A&M Transportation Institute
TAMU 3135
College Station, Texas 77843-3135
(979) 845-8955
[email protected]
Pooled Fund Technical Representative:
Michael Elle, P.E.
Design Standards Engineer
Minnesota Department of Transportation
395 John Ireland Boulevard, MS 696
St. Paul, MN 55155-1899
(651) 3664622
[email protected]


The objective of this research was to evaluate the use of a 31-inch tall, strong-post W-beam guardrail with 12 ft-6 inch post spacing and 8-inch deep wood blockouts at MASH Test Level 2 (TL-2) conditions. A typical strong-post W-beam guardrail uses 6 ft-3 inch post spacing. A guardrail system with fewer posts will be less expensive and therefore more cost-effective on low-speed roads.

The 31-inch W-Beam guardrail with 12 ft-6 inch post spacing contained and redirected the 2270P MASH test vehicle. The vehicle did not penetrate, underride, or override the installation. Maximum dynamic deflection during the test was 36.4 inches. One of the blockouts separated from the rail element and post; however, the blockout traveled low to the ground and came to rest on the field side. It did not penetrate or show potential for penetrating the occupant compartment, or to show hazard for others in the area. The 2270P vehicle remained upright during and after the collision event. Maximum roll and pitch angles were 6 degrees and 7 degrees, respectively. Occupant risk factors were within the preferred limits specified for MASH test 2-11. The 2270P vehicle exited within the exit box criteria. The 31-inch W-Beam guardrail with 12 ft-6 inch post spacing performed acceptably for MASH test 2-11.

MASH TL-2 Guardrail prior to Testing
MASH TL-2 Guardrail after Testing


Not applied.