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Very Shallow Guardrail Post at Subsurface Obstruction

Question
State MO
Description Text

The following is a description of my guardrail repair situation.  Location photos are attached.

 

Object being shielded is an existing retaining wall 2 feet off right edge of roadway shoulder.

Existing guardrail totally destroyed in vehicle crash.

Existing rail was offset 5 to 10 feet behind curb and "U-shaped" gutter.

New guardrail will be installed along edge of shoulder with posts through the "U-gutter" and face of rail blocked out in front of curb face.

"U-gutter" behind curb and guardrail will be filled with rock to provide smooth transition from pavement to roadside without a dropoff behind curb.

New guardrail will attach to wall with a thrie-beam shaped bridge anchor section, then thrie beam/w-beam transition section, then 87.5 feet of w-beam guardrail, then 50 foot crashworthy guardrail end terminal (ET-2000).

A new 10 foot section of concrete barrier was poured at end of retaining wall to provide solid attachment for new bridge anchor section.

Approximately 50 feet upstream from the wall is a 48 inch drainage pipe that crosses at right angles to the roadway approximately 24 inches deep.

Guardrail post falls directly on the pipe (we drilled into pipe).

We are unable to offset post due to equipment mobilization issues which preclude us from drilling any more holes through concrete "U-gutter".

 

I would like to either skip this conflicting post or use a short post on top of the pipe.  Please review and provide a response for how best to handle the conflicting post.


Working Width and Zone of Intrusion

W-beam Guardrails

Midwest Guardrail Systems (MGS)


Date February 10, 2005
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Attachment P6260009.JPG Attachment P6260016.JPG Attachment P6260024.JPG
Response
Response
(active)

As we discussed on the phone, one short post in the middle of a run of guardrail should not need any other treatment.  In order to be safe, you should consider nesting the G4(1S) W-beam for 25 ft over this region. MGS with an omitted post does not require nesting adjacent to the omitted post.

I noticed that there is a curb all along this section.  The current recommended treatment for G4(1S) guardrail with curbs is to incorporate nested rail throughout the entire area where there is a curb.  When MGS is used in conjunction with a curb and an omitted post, the W-beam should be nested for a minimum of 37 ft - 6 in., roughly centered on the omitted post location. MGS placed adjacent to curb does not require nesting except near omitted posts.


Date February 11, 2005
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