Reddit reviews Access All Areas: A User's Guide to the Art of Urban Exploration

Oh yeah and buy this book rather than mine: http://www.amazon.co.uk/Access-All-Areas-Users-Exploration/dp/0973778709

Tunnels:

Most of the steam tunnels around campus are located under bike paths (easier to dig up if the need ever arises). It's pretty simple to figure out where the tunnels are by observing the location of the hatches you see, JULIE markings (steam tunnels are normally denoted with yellow spray paint), or by looking to see where water dries or snow melts a bit faster than everywhere else. The Campus Administrative Manual states that all new steam tunnels will be "shallow" tunnels (about 3 feet tall, most of which is taken up by the pipes). Instead of allowing maintanence workers to comfortably walk down the tunnels (most of the old tunnels are 8' tall and 6' wide - roughly 3' after the pipes and their supports), the sidewalk is broken up into liftable concrete pieces. Figuring out which tunnels are shallow and which are "normal" is often difficult.

Pipes:

The tunnels house pipes that transport steam, cold water, and in one place, fuel. Because steam is highly corrosive, the pipes are designed to be replaced periodically. New pipes are made of PVC and are well insulated, so they need much less care. On top of the pipes, there are assorted valves, steam traps, sump pumps, and other equipment.

Buildings:

The tunnels often connect to various buildings around campus. None of the dorms connect. Almost all of the buildings on the Quad (with Lincoln Hall being the notable exception) can be accessed from the tunnels. The tunnels lead into a mechanical room in the building (nicknamed the "hot room"). Exploring buildings from the tunnels is a great way to get caught - doors lock behind you, there's a much higher chance of someone being there late at night, etc. The only case I know of someone getting caught in the UIUC tunnels was a result of exploring a building.

Physical Dangers:

The tunnels are a hazardous place. The main reason I'm taking the time to post this is to make sure that if people do explore the tunnels, they do so safely.

The pipes are hot. The valves are hot. Steam leaks happen - best case, you hear a hiss and can locate the leak and avoid it. Worst case - the leaks are often periodic in nature. They'll burst some steam every few seconds/minutes. There is asbestos covering some of the pipes. This isn't a danger unless disturbed - try your hardest not to disturb it. There's a lot of rusty metal, and there are places where water collects. Pay attention to where you're walking, and avoid walking through water - you never know what could be in it.

Legal Dangers:

First off, the police will never follow you into the tunnels. They are not willing to risk their safety in order to catch someone for trespassing (technically criminal trespassing on state property). That doesn't mean, however, that you shouldn't be extremely careful entering the tunnels. If you are spotted, you'll have a much harder time getting out unnoticed. Getting out is much easier - pick a hatch in a secluded spot, that has a grate you can scan the area from. There is an increasing number of cameras around campus, and all outdoor cameras are equipped with an infrared spotlight. Be aware of when you're nearing a hatch or other opening, and keep your voice down, and do your best to hide your flashlight.

If you do get caught, you're likely looking at probation from the University, and about 60 hours of community service. Your employer will likely be notified, and most don't appreciate hearing about a court case. Student Legal Services, in the Union, is a great resource for times like this.

Getting In:

You only need to find one entrance. Once you're in, you can go around propping other hatches to maintain future access. Check construction sites. Keep an eye out for service vehicles. Pull on every hatch you see - eventually you will find an open one.

Resources:

inflitration.org is a great resource for urban exploration (specifically this page). If you find that information useful, I cannot recommend their book enough.

Protips:

Bring plenty of Gatorade (throwing the bottles in the freezer beforehand is a nice touch). Bring flashlights and extra batteries. Bring a small first aid kit. Bring at least one friend. Let someone know where you're going and when you expect to be back. These might seem like overkill, but people have gotten seriously injured. These simple extra precautions will go a long way towards keeping you safe, and the extra peace of mind will make your trip more enjoyable.

Stay south of Green. The tunnels on the north side don't connect together well, and many systems have a single entrance/exit.

Be considerate - there are a lot of random artifacts from earlier explorers (can you find a beer can with a pop top?). Don't take anything, and try to minimize your footprint. If you want to tag the walls, use chalk.

Some not well known secrets: There are multiple levels of tunnels. There's a mailbox where you can leave/read messages. If you're not careful, you can easily find yourself in the power plant (AKA "Hell").

Don't touch anything. The main reason access is tightly controlled isn't because of any liability reasons - a simple spin of a valve can have catastrophic consequences when it's controlling highly-pressurized steam. There are a lot of things that look like light switches - and most of them are. Some, however, control other equipment.

Finally, be alert, be careful, and be aware of your surroundings.

It is not. I am very serious.
Urban exploration, often called "infiltration" is an underground, often illegal activity closely related to better known activities such as parkour and graffiti.
I suggest your read the book Access All Areas: A User's Guide to the Art of Urban Exploration if you wish to know more about that activity.

Suggesting your own punishment is a good idea if "caught". i.e. saying, "Hh, I guess you want me to leave now." or something like that can help both parties out. Helps them because "they came up with the idea" and it helps you because all you have to do is leave.

"Access All Areas" by the late Ninjalicious can be a good resource for lots of this stuff, check it out. )

http://www.amazon.com/Access-All-Areas-Users-Exploration/dp/0973778709

Half of the fun of this activity is doing the research and scouting.

There is a really good book I highly recommend called: Access All Areas: A User's Guide to the Art of Urban Exploration. You can probably find a PDF for free somewhere if you can't afford it.
The book has a vast amount of good information to know about all kinds of urban exploration, including exploring construction sites.

Related book recommendation: http://www.amazon.com/Access-All-Areas-Users-Exploration/product-reviews/0973778709/

Ever tried Urban Exploration?

http://www.infiltration.org/hotels-plunge.html

The book-

http://www.amazon.com/Access-All-Areas-Users-Exploration/dp/0973778709

Sounds like you have some experience - so far I've only been to a couple of buildings around Oakland and read this book. Any advice for someone just getting started?