"Calgary mulls downtown Green Line LRT route options"
http://www.cbc.ca/news/canada/calgar...town-1.3362093
I personally think this should be done properly. Spend the money, put it underground (as much as possible) like most modern cities do. Leaves the Centre Street bridge open to vehicles, bikes and current traffic. I feel any other option will simply slow any type of existing commute without massively altering the Centre Street landscape.
Vancouver's train line goes underground, and it works EXTREMELY well through the neighbourhoods.