I currently work in that area (Won’t say what department for privacy reasons) and it is at times almost concerningly easy to get back there if our crew isn’t in our area working. To the point that sometimes we worry about it when we leave; but we’ve also never seen anyone stupid enough to do it. We use those service roads near daily and have always had the system of ‘guests couldn’t be that reckless, could they?’ and, well… :/