View Q&A

Its it possible to reduce the MGS deflection to 12 inches
measured from back of post to hazard?  Such as nested rail with quarter
post spacing or use larger posts similar to w-beam to parapet transition
designs?

Thank you for your time,

We do not have any data to support the reduction of the MGS deflection to the level of 12 inches measured from back of post to hazard. During NCHRP 350 TL-3 testing of the MGS, we evaluated a ¼ post spacing system that had a dynamic deflection of 17.6” and a working width of 36.7”.

The working width value is taken from the front face of the guardrail. As such, this would correspond to a clear distance from the back of the post to the hazard of only  15.4”.

There is potential to further reduce that deflection through the use of larger posts and or nested guardrail. However, we have not developed that kind of system to date. In order to determine what the deflection reduction would be and the effect on the overall performance of the barrier, further analysis and/or crash testing may need to be conducted on a modified system.