A friend has just bought 10 acres (and a house) that the M1 runs alongside. She has hugely increased her public liability! Very good move, IMO. My old yard had the M1 at the bottom of the boys’ field, with very dense hedging enhancing the fencing. It never really worried me, but given what an escape artist mine was once at the current yard, I should maybe have been more worried.
The m25 runs along the very top end of the farm mine are on, we don't keep the horses at that end as it's got storage units rented by people up there. We do keeps all lower gates shut at all times as a safety measure though.