Here is a project that is helping to give light rail a deservedly bad reputation, at least as far as capital costs go. The Detroit's Downtown Development Authority just approved $9 million to help build a $120 million LRT line. The good news is most of the money for the line is privately supplied. The bad news is Detroit doesn't have the necessary conditions for LRT to succeed. The biggest problem is Detroit is shrinking, specifically the employment base is shrinking. As employment centers are the biggest predictor of transit usage, this doesn't bode well. It's also not clear if there is any residential density near the stations in order to fill the trains, and as the city is losing population this is not going to get better. I also doubt Detroit is suffering from heavy congestion.
The biggest worry is more fundamental. Why are business leaders in Detroit fighting for a partially privately funding LRT line in the first place? Not having LRT is not Detroit's biggest problem. Not enough cars probably is closer to the top of the list. Granted, Detroit sees the demise of the carmakers and wants to broaden their industries and occupations, but direct subsidies to businesses and residents is a much better way to spend money than on LRT. Detroit should focus on generative economic policies, not redistributive transportation projects.