The S-curve isn't a place where someone would normally pull off to use as a rest area unless it was a dire emergency. The green gate wouldn't be a place to go behind--that's always been a formidable gate, even when it was just a metal gate (the location just screams GO AWAY). So while someone COULD pull to the side, and certainly I've seen vehicles parked in that vicinity, it's just highly unlikely. The S curve has a "let's get through this and get the heck out" kind of feel. It's narrow and sharp, with signs indicating speed drop to 19, flashing lights, etc. When you walk it, it's relatively dark, and there's a steep uphill rise, although you can't tell from any photo, and plenty of vehicles have taken the curve way too fast and gone flying off the road. You always drive it wondering who is coming around the bend and how fast they are going. hope this helps.
