Several years ago I found a good supply of tri-rail (20" wide) and bought a semi load of it.  Worth the money cause it was taken down in a hurry with a chopsaw -- one end cut off - but that end was still bolted onto the next piece, so I got a tremendous supply of galvanized bolts as well.  Unbolt the cut off end, take it to the other end, overlap it a bit and weld it back on.  Cattle don't seem to mind.

Put up on the original I-beam posts.  2  -- 5'6" guardrail posts welded together end to end.  Use three of these rails spaced just wide enough to get your foot through in case you need to climb over.  Pretty good windbreak in bitter cold weather as well.

(guardrail (sm).jpg)

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