Unlike in most large cities, it would be so easy to figure this out in Detroit. We have thousands of miles of underused, or unused, right-of-way including railroads where tracks have been removed and surface streets that are 3X wider than they need to be. You could start by taking every spoke road [[with the exception of Woodward) and eliminate half the car lanes and convert to rail.

I'd still rather see the area contained within Grand Blvd connected with additional streetcar lines to bring together our cities greatest assets and re-densify the core, but that will probably never happen.