Private builder MTR Corporation of Hong Kong worked with the government of Shenzhen, China to build a new $7 billion rail system, even though they new from a study they commissioned that railway investment "is not financially viable on its own." The MTR concluded that if the Hong Kong government gave them property adjacent to the system they could make it pencil out.
From The Economist:
"The results have not been entirely successful. Some of the MTR projects reflect the worst of bleak government architecture but over time its portfolio has become a bit smarter; and these property holdings, along with the lease of advertising space, now account for more than 60% of MTR's revenues and presumably all of its very healthy profits, as well as providing the financial strength to support its spotless metro service."
