View Q&A

Attached to this e-mail is a draft of KDOT's short radius guardrail standard drawing, which I've updated for the MGS. I'm aware you and Scott have been communicating wrt to this topic and no approved system has been designed or tested for the MGS. KDOT is interested in modifying our existing standard drawing in accordance with TTI's analysis and report (see attached) in the hopes of submitting the standard drawing for federal approval to allow KDOT to use the system on our projects in the interim period until such a time an approved short radius system becomes available. Please take some time to review the attached drawing and make any appropriate comments. I look forward to hearing from you and greatly appreciate your help. Please call if you have any questions or would like to discuss this further.

I do not recall giving any guidance that would support the use of the MGS as a short radius guardrail system around the nose of the device. Scott may have to refresh my memory on this issue. It is possible that we would have discussed eventually transitioning the w-beam to MGS after traveling along each of the two sides. For high-angle impacts on the nose, there may be some concern that the small car cannot be captured and instead would underride the rail. In order to improve capture, many prior studies had investigated the use of a thrie beam rail in the nose section under TL-3 test conditions. Although some promise was revealed in testing of the latter design, the project was abandoned. Unfortunately, the configuration of the primary side became unreasonably long, which made the overall system impractical to install.

Currently, it may be necessary to utilize the existing Yuma County system or modifications noted by TTI. After traveling down the sides, then the guardrail could be transitioned to the MGS. Please let me know if you have any questions or comments regarding this information.