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Some time back, you inquired into the metric-height, W-beam guardrail system with half-post spacing that was previously developed for attachment to the top of concrete box culverts. Specifically, you asked whether this design could be modified and used in combination with the MGS. In 2007, we addressed this issue and provided an opinion on this matter. I have copied the response from the prior email and placed it directly below.

NDOR

(3) No crash testing has been performed on an MGS guardrail system attached to a concrete culvert. MwRSF currently has a Phase I project (Year 18) to conduct the initial concept development for the MGS bridge rail system. Phase II funding will be requested in the Year 19 program. Once the MGS bridge rail is crash tested and successfully evaluated, it may be necessary to acquire a smaller research project to adapt the system to culverts (i.e., top of slab, top of headwall, or back side of headwall).

WY: Is it acceptable for us to adapt this design for use with the MGS?  Given the MGS's improved performance, it would appear and acceptable design.

*****MwRSF: Due to the superior safety performance of the MGS, it is our opinion that the metric-height, W-beam guardrail system attached to concrete culverts should be capable of be adapted for use with the MGS. Since the MGS design will result in increased barrier deflections, it would be reasonable to increase the minimum post offset from 10 in. to 12 in. or more.