Here's a Lumec Helios streetlight fixture that's pretty common in Newmarket, although I haven't seen a lot of them anywhere else in Ontario. I've also seem them in Quebec too on the Autoroutes/Freeways there.
Yes, the Lumec Helios has only sag and flat optics.Yes its sealed,the reflector assembly is attached to the bottom door,and when its opened the socket/lamp is accessable by twisting it out, similar to an automotive halogen.