I attend Southern Methodist University in Dallas in the early 90's (gad, that dates me) and, out of curiosity, a group of us started investigating the tunnels that were rumored to run around under campus.

Tunnel Legend:
Supposedly, the underside of the SMU campus is riddled with with steam tunnels. This isn't exactly hard to believe, as almost all of the tunnels have ground-level ventilation and access hatches. Basically, if you find a metal plate or a metal grid set in concrete somewhere on the campus, you have found a steam tunnel. The ones with grates are the easiest to identify as you can look down and see the steam pipes. Also, there are places where the ground has sunk a bit except for where the tunnels are - it's pretty obvious when you trip over one of them .

Tunnel Plan:
I don't have a plan for the tunnels, but they seem to run from the physical plant on Airline road to most of the older buildings on campus. A number of buildings have been built since I graduated and I don't know exactly how they are connected. I did investigate the new Greer Garson theater when it was being built and I never found the connection to the tunnels.

What I do know is that the tunnels connect all the buildings in the North Quad (Mary Hay, Peyton, Shuttles and two other dorms) to the old Umphrey Lee student center (now the cafeteria and bookstore). I lived in Mary Hay and we used the tunnels to access Umphrey Lee after hours - generally to either raid the kitchen (in the basement) or the wine cellar (on the third floor behind the ballroom). This was generally considered to be a "Tuition Reimbursement" visit - SMU was expensive and most of us were broke. It's a lot of work to carry a case of wine through a steam tunnel, but the effort is generally worth it.

Tunnel Details:
The tunnels are concrete lined, 3 to 5 feet high and about 3 feet wide. They are lit in some areas and not in others. There are occasional rooms - generally near a building. Easiest access is generally from the mechanical rooms in the basement of the buildings. I discovered that the locks were easy to pick or the rooms were left open, which gave access to the tunnels - all you had to do was follow the pipes to a corner of the room and you would be in the tunnels.

Some of the buildings had metal grates guarding the entrances, which may or may not have been locked. Others (I think Umphrey Lee was one) just had hard-to-find and unmarked entrances. One thing to remember is that the tunnel entrance might not be in a wall facing the ultimate direction the tunnel takes. If I remember correctly, the mechanical room in Umphrey Lee was reached by taking the stairs from the loading dock down to the kitchen. There were two doors - one went to the kitchen and the other to the mechanical room.

Basically, we "fixed" the lock in the Mary Hay mechanical room so that we had easy access. In addition, I "acquired" keys to all of the mechanical rooms when I worked at the college one summer - made access to things much easier.

As I said above, it's been a few years, so the details I remember are a bit vague. I do remember that there were motion sensors in places in Umphrey Lee and the kitchen had cameras - which were pointed at the ceiling (hmm, maybe we weren't the only ones doing some raiding).

Security:
I'm sure the buildings are patrolled these days - they were starting to when I was there. Umphrey Lee was actually the easiest to avoid people in - we would go in before it was locked down and hide in the attic over the ballroom (usually with some "refreshments"). Once things quieted down (and after appropriate recon) we would raid the wine celler (behind the ballroom), send the goods down the dumbwaiter to the kitchen (no use carrying them farther than you have to) and then take the back stairs to the kitchen. The required doors were unlocked, goods were moved to the tunnel entrance, and then things were shut back down. We were always carefult to leave few signs of our presence.

Dorm security varied depending on the building layout. One of the tunnels exited into a junk room. We thought this was great until we discovered that the exit from the junk room was across the hall from the RA's room - and he generally had an "open door" policy - how inconvenient. Most of the other entrances were in basements where there was little activity after hours.

Scouting beforehand was definately a good idea - spend some time walking around the campus looking for tunnel entrances in the ground, strange patterns of grass dying (in the summer) and puffs of steam vapor in the winter. In buildings, check the basements for mechanical rooms, which are frequently identified. Also, watch where pipes go - they generally lead back to the mech room.

Another consideration is when to make visits - we generally preferred early Sunday morning as that seems to be the most "dead" time on campus. Buildings that were locked up tight were infiltrated in the early evening - generally we tried to hide in the attics or elevator control rooms. All buildings are easy to get out of as they have "crash bars" on the doors.