C++ Friend Functions and Linker confusion

I am trying to compile and run boost example code you can find at http://ift.tt/1SYbFY0, however, I keep running into some problem with linking the code. I get about 6 error messages that look very much like the one below.

LNK2005 "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class bus_stop const &)" (??6@YAAEAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AEAV01@AEBVbus_stop@@@Z) already defined in bus_destinations.obj

My guess is that the linker needs help sorting the friend functions contained. I would appreciate some help in resolving this issue, please.