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Guardrail Blockout compressive Strength

Question
State	NE
Description Text	The importance of the 12” blockout in the MGS, from what I recall - is to keep the tire of the pickup away from the post. Could a lightweight blockout weaker than what was tested improve the performance of the MGS? Assuming the answer is no; Is there a minimum compressive strength of a guardrail blockout between the post & the back of guardrail? Or What’s the strength needed to redirect the pickup away from the post when impacted?

Question

State

Description Text

The importance of the 12” blockout in the MGS, from what I recall - is to keep the tire of the pickup away from the post.
Could a lightweight blockout weaker than what was tested improve the performance of the MGS?
Assuming the answer is no; Is there a minimum compressive strength of a guardrail blockout between the post & the back of guardrail?
Or What’s the strength needed to redirect the pickup away from the post when impacted?

System Performance Evaluation

System Types
Road Closure Gates
Thrie Beam Guardrails

Applications

System Features

Date August 15, 2018
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Response
Response (active)	The blockout was used to reduce wheel contact with the posts for both vehicle types and to hold the rail up longer during lateral post movement & rotation. The standard MGS was tested with 12” blocks (MwRSF and others), 8” blocks (TTI), and no blocks (MwRSF and others). We found improve performance for larger blocks versus no blocks, although all options worked for base configuration. With weaker blocks, those that fracture or crush, we would expect acceptable performance in the base configuration. However, I could not say that it would be improved performance over that observed with 12” wood blocks. Even with blocks, we may still have wheel contact with posts for both vehicle types. Unfortunately, we do not know the minimum compressive strength to provide similar safety performance to that observed for standard MGS with 12” wood blocks.

Response

Response
(active)

The blockout was used to reduce wheel contact with the posts for both vehicle types and to hold the rail up longer during lateral post movement & rotation. The standard MGS was tested with 12” blocks (MwRSF and others), 8” blocks (TTI), and no blocks (MwRSF and others). We found improve performance for larger blocks versus no blocks, although all options worked for base configuration. With weaker blocks, those that fracture or crush, we would expect acceptable performance in the base configuration. However, I could not say that it would be improved performance over that observed with 12” wood blocks. Even with blocks, we may still have wheel contact with posts for both vehicle types. Unfortunately, we do not know the minimum compressive strength to provide similar safety performance to that observed for standard MGS with 12” wood blocks.

Date August 15, 2018
Previous Views (120) Favorites (0)