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MGS W-Beam Guardrail Grading vs. Strong Post Guardrail Grading

Question
State IN
Description Text
 The recommended grading around MGS w-beam guardrail is a maximum slope of 10:1, from the face of guardrail to a shoulder slope break 2 ft behind the back of the
guardrail post. This recommendation is for both signal and double face MGS w-beam guardrail. See the attachment. Can these same grading recommendation be
applied to strong post guardrail? Currently INDOT recommends a maximum slope of 20:1 rather than 10:1. Thanks




Date June 20, 2019
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Response
Response
(active) 		You are correct that the current guidance for the MGS recommends level terrain or 10:1 slopes in front of the barrier and for 2' behind the barrier for the standard installation. 

This guidance evolved from previous guidance used for the G4:1S W-beam and other NCHRP 350 barrier systems. As such, we believe it is acceptable for use with previous NCHRP 350 longitudinal barriers unless new evidence supporting shallower slopes is developed.
Date July 30, 2019
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