Last night, I saw a used CAT 302.5 mini-excavatoron eBay for under $10K. And a brand new 30-inch flail mower would run about $5,000. I think a small, heavy-duty purpose-made flat car would be better than hy-rail gear. Actually, with rubber treads, running a mini-excavator on the ties is not going to do any appreciable damage to the track. The whole rig weighs less than six tons and would spread out over four or five ties. Why complicate the issue?