I decided to update my map to include a connection to Metro Airport as well as Pontiac and Utica. The "Utica Line" (U) covers the inner-ring suburbs and allows for riders in those suburbs to bypass the central city if they are heading to the Airport which is now reached by an extension of the Michigan Line (M). The Woodward Line (W1) has also been extended and split with one spur ending in the business district of Troy and the other spur turning back towards Woodward and paralleling it to Pontiac.
I contemplated extending lines into Downriver or eastern Macomb County, but these areas don't really have issues with congestion outside of large construction projects. Rapid transit lines probably wouldn't make a different in commute times and the lines here would probably have low ridership compared to other routes. For the rest of the Metro area, I feel that rapid transit lines become less effective with distance relative to cost especially in the outer ring and far flung suburbs. At that point, bus service and commuter rails would be more useful.
