I used to hunt a CRP field that was right on US 50 in western Kansas. The cover was separated from the highway by only a typical mowed highway ditch. It was probably 120 acres and I would only run my dog if we were working all the way on the inside of the field, ie, as far as possible away from the highway. It's a 65 mph road and people routinely drive 70+. Not a problem now because it came out of CRP...