View Q&A

I get asked this question pretty often.  Does the work that you are doing for Wisconsin address the minimum length issue?

I am considering placing a 100' minimum length requirement in the new manual, exclusive of terminals, when installation is not attached to a structure (parapet, barrier wall).  This essentially provides 137.5' of w-beam guardrail toward the length of need.   Are you comfortable with this or should we use a longer minimum installation?

MwRSF has recently obtained funding to investigate the minimum guardrail length issue. For the minimum guardrail length study, system lengths less than 175 ft will be evaluated in terms of effectiveness, working width, and dynamic barrier deflection.

Based on crash tested system lengths, we have suggested that a minimum system length of 175 ft be used for TL-3 applications. This system length includes the use of guardrail end terminals. Guardrail end terminals can be used to configure the overall system length. For example, the interior guardrail length would be 100 ft if each end included the use of a 37.5 ft long FLEAT guardrail end terminal. We recognize that there exists is strong likelihood that system lengths less than 175 ft will be capable of containing and redirecting heavy passenger vehicles occurring at high speeds and angles. However, we are unable to definitively provide guidance on the minimum barrier length for W-beam guardrail systems or on placement in front of hazards. For now, I would recommend that you maintain the use of the 175 ft system length.