I was reading Christian Wolmar's excellent Blood, Iron, & Gold. on p. 231 he says:
"Railways provided a far more enduring boost to the economy than the construction of roads or even canals had previously. Once a road was built, apart from the occasional patching up, it could be largely left alone. In contrast, railways not only needed continual maintenance, such as regular patrols checking that the track was safe, but also required a sizable organization to operate them involving thousands of workers."
``Boost to the economy'' is a really nice way of saying they incur many expenses.
Great quote, I think the whole railroad industry is slowly going out of business, here is an interesting article http://usgovinfo.about.com/od/consumerawareness/a/amtrakrip.htm