I attended OIT (Oregon Institute of Technology) which is actually a Oregon State four year school in Klamath Falls Oregon in 1993. Klamath Falls is about 30 miles south of Crater Lake, and is quite volcanically active. In fact, the entire town, and the school in particular are sitting right on top of a fault line. The school has about five various buildings for classrooms, a library, the college center, the Administration building, and one dorm building. In the middle of the campus is a large concrete building which houses all the heating equipment. Most the steam tunnels around the school run directly under sidewalks, keeping them totally clear of snow during the winter (which explains the way all the concrete sidewalks have 'potholes.') The heating building sits right on top of a large piece of the fault line itself, in fact the last part of the tunnel is actually a smallish lava tube that has very large steam pipes running through it, nothing more then a small animal would be able to get through here. This is also the hottest parts of the tunnel, very close to 200 degrees. To keep all the equipment cooled down, two very large 10 foot diameter fans are built into the top of the building. Steam tunnel access itself is achieved primarily through an access grate about 100 yards south of this building. Tunnels run to all buildings on campus. The only buildings that are locked are Campus Security, Administration, and the Dorms. (As the basements are also used in all three of these buildings.) The newest building, Hall which is also the Computer Sciences building has about 100 feet of new (1992) tunnel, but again, no lock. You can also access the tunnels through the drop floors in both the main computer lab, and two of the computer labs in Hall. There is an elevator in the College Union that goes down to the basement with quick access to the steam tunnels, but it's accessible with only five keys on campus. Most the tunnels are very large, 5-6 feet across. They are also meant to be emergency routes in case of heavy snow. While they are quite wet, they are well lighted if you access them from Campus Security, or the Administration building. (There are light switches at both locations on the outside of the locked doors, i.e. unreachable from inside the tunnels.) I first found out about the tunnels when working in Food Services in the Student Union. After a particularly heavy snow, the head of food services and I both took a food cart normally wheeled across campus down the elevator to the basement, and across to the P.E. building, then onto Hall Building. I later found out that many people used the same tunnel to access the indoor swimming pool in the PE building, and the computer lab for extra time on the mainframe during the early 80's, but campus security had cracked down hard on that. I was only ever able to get in once again through the Elevator (which I had a key to, being a manager of Food Services), and explored enough to find out about the Administration and Campus Security being locked. As far as I know and have heard, everyone else who's ever gone into the tunnels has been caught, as they regularly patrol the tunnels themselves.