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Bolt Holes in Guardrail Posts

Question
State	IA
Description Text	We will be allowing the use of steel guardrail posts here soon, and I have a quick question. Does it matter to which side of the flange the holes are drilled? It seems that most states show the holes to the right of the flange on the elevation/front view. Would you see any benefit to drilling holes on both sides of the flange?

System Performance Evaluation

System Types
W-beam Guardrails

Applications
Midwest Guardrail Systems (MGS)

System Features
Material Specifications/Alternatives

Date June 8, 2011
Previous Views (19) Favorites (0)

Response
Response (active)	We typically place a hole on the upstream side of the front flange as well. However, I believe that the guardrail system would perform in an acceptable manner if the bolt were placed on the downstream side of the front flange as well. In most reverse direction impacts, the guardrail bolt would effectively be located on the downstream side of the front flange. Many suppliers are fabricating guardrail posts with hole punched on both front and back flanges as well as left & right sides of each flange. The additional holes allow for the post to be more easily placed at a guardrail slot location without concerns for direction, side, etc. In general, it would seem reasonable to try to follow a practice of placing guardrail bolt on upstream side of front flange. On another note, there may be a very slight increase in costs to punch all of the extra holes, depending on how the punching/drilling process was completed.

Response

Response
(active)

We typically place a hole on the upstream side of the front flange as well. However, I believe that the guardrail system would perform in an acceptable manner if the bolt were placed on the downstream side of the front flange as well. In most reverse direction impacts, the guardrail bolt would effectively be located on the downstream side of the front flange.

Many suppliers are fabricating guardrail posts with hole punched on both front and back flanges as well as left & right sides of each flange. The additional holes allow for the post to be more easily placed at a guardrail slot location without concerns for direction, side, etc. In general, it would seem reasonable to try to follow a practice of placing guardrail bolt on upstream side of front flange.

On another note, there may be a very slight increase in costs to punch all of the extra holes, depending on how the punching/drilling process was completed.

Date June 8, 2011
Previous Views (19) Favorites (0)