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A representative from FHWA resource center is asking for the report that MwRSF ran that involved 4" mountable curb and standard beam guard.  He also was wondering why NCHRP Report 537 indicates that standard  barrier can be installed at a zero offset and MwRSF's failed crash tests with standard beam guard.

If MwRSF could get me the report number and title and MwRSF's opinion on NCHRP 537 recommendation.

MwRSF performed two research studies for the Midwest Pooled Fund Program regarding standard strong-post W-beam guardrail installed over 4" concrete curbs. The research results from these studies are published in the following reports: TRP-03-83-99 and TRP-03-105-00. I will email you these reports in separate emails using the UNL DROPBOX SYSTEM.

MwRSF found that a steel post, wood-blockout, w-beam guardrail would rupture when placed over a 4-in. wedge-shaped, concrete curb. TTI found that a wood post, w-beam guardrail would redirect a pickup truck when placed over a 4-in. asphalt dike. MwRSF later obtained a successful test result when the single rail was replaced with a nested guardrail.

NCHRP 537 makes the statement regarding 4-in. curbs being placed flush with the guardrail face based on prior crash test data noted above, LS-DYNA simulations performed in the study, and the lower speed validation crash tests performed for NCHRP 537. As such, NCHRP 537 is silent on the issue of which W-beam rail system modified G4(1s) or G4(2W) can be used with single rail or nested rail.

Later, MwRSF demonstrated that the Midwest Guardrail System (MGS) could be used with a 6-in. curb placed slightly forward of the rail face.