http://www.detroitthermal.com/

Fast-forward to the 2:00 mark to get a high-level overview:




Detroit Thermal provides many downtown and midtown businesses with steam energy that is used to heat buildings and water, as well as other functions too.

Here is a service map: http://www.detroitthermal.com/servic...vice_area.aspx

Here's another map:



Here's another map that better notes the transmission pressures: http://www.tvii.biz/detroit/LINKS/DT...450%20copy.jpg

The steam is transmitted under very high pressure through underground steam mains. Sometimes water will get into these pipes, and when that happens it causes a rapid expansion of the water and sometimes will cause scenes like this ConEd pipe in Manhattan:






I hope you find some of that interesting and helpful.