The "last best chance" for connecting downtown Detroit with the rest of the metro area via commuter rail rests on a barely-surviving railroad right-of-way, extending west along the north side of West Jefferson Avenue from the 40-year-old Joe Louis Arena Parking Garage (which will soon be re-opened and re-named, and NOT demolished).
The garage is located adjacent to soon-to-be-renamed Joe Louis Arena Detroit People Mover (DPM) Station. The oft-ridiculed DPM system was intended to circulate rapid transit passengers to and from their actual downtown destinations -- unfortunately, the rapid transit systems were never built. In current practice, DPM circulates motorists between destinations and parking lots.
The north side of the garage was built with extremely-tall vertical clearances, which were intended to enable a commuter rail passenger terminal. West of the garage, Sixth Street Overpass crosses over West Jefferson and a parallel railroad right-of-way easement, which has been trackless and vacant for more than fifty years.
The garage was built on the site of Pennsylvania Railroad (PRR) Third Street Package Freight Terminal, which opened during October 1923. Elevated tracks from the Penn High Line entered the second floor of the stub-ended rail-freight facility. The Penn High Line tracks diverged from the elevated 1892 Fort Street Union Depot (FSUD) Viaduct tracks just east of Cabacier Street.
Demolition of the Penn High Line, along with the PRR freight terminal, was completed in 1962. FSUD and its eleven-block-long viaduct (the longest railroad bridge ever completed in Detroit) were demolished in 1974.
West of Sixth Street and east of Cabacier, the wooded embankment of the former - Penn High Line is still-extant and vacant, running along the north side of West Jefferson.
West of Cabacier Street, a narrow strip of vacant parkway still parallels the north edge of West Jefferson Avenue, adjacent to Fort Street Post Office.
There's still a chance that this former - railroad right-of-way could be revived as a commuter rail line, running along the north side of West Jefferson as far as the former - Michigan Central Railroad (M.C.R.R.) Mays Creek mainline (aka "the moat").
When M.C.R.R. relocated its Detroit terminus from Michigan Avenue at Griswold Street (near Campus Martius) to the foot of Third Street (today's Steve Yzerman Drive) in 1848, the railroad's mainline was moved to the former-bed of Mays Creek, which provided a naturally-occurring, depressed-diagonal, grade-separated "water level route" to the riverfront -- analogous to Grand Trunk Western Railroad's east-side Dequindre Cut (today's Dequindre Cut Greenway rail-trail).
This long-vacant "surface route" (relative to the 1910 M.C.R.R. Detroit River Tunnel far below) could be revived, extending the commuter rail line to Ford Motor Company's recently-acquired Michigan Central Station (MCS), and all points
northeast (Fraser, Mount Clemens, Port Huron),
north (Warren, Sterling Heights, Utica),
north-by-northwest (Ferndale, Royal Oak, Birmingham, Pontiac, Flint),
northwest (Livonia, Plymouth, Brighton, Northville, Farmington Hills),
west (Dearborn, Inkster, Wayne, Ann Arbor),
west-by-southwest (Dearborn, Allen Park, Taylor, Metro Airport, Milan),
southwest (Melvindale, Lincoln Park, Southgate, Flat Rock, Carleton, Toledo), and
south (River Rouge, Wyandotte, Trenton),
using existing heavy-rail lines.
Southeast of MCS, the long-vacant, grade-separated railroad right-of-way varies in width from 40 to 150 feet, allowing for the creation of a trail-with-rails greenway paralleling the south side of the revived double-track commuter rail line. West of MCS and the nearby rail tunnel portal, commuter trains could run along the still-active Canadian Pacific Railway (CP) mainline.
Running west toward Dearborn, this CP / Conrail mainline (like the Dequindre Cut Greenway on Detroit's east side) is grade-separated and limited-access. It crosses over streets on still-sturdy, century-old railroad overpasses, including the 1896 "Cloud Bridge" arch over West Grand Boulevard (the oldest railroad overpass in Detroit).
At Bay City Junction, West Detroit Junction, CP-LOU (near Wyoming Road), and Town Line Junction in Dearborn, heavy-rail lines diverge from the east / west mainline in all directions.
West of Town Line, Michigan Department of Transportation (MDOT) owns the Michigan Line mainline as far as Kalamazoo. This segment of Amtrak's Pontiac / Chicago WOLVERINE route is being upgraded to enable 110-mph rail passenger service.
The recently-proposed T LINE (T for Toledo) high speed rail (HSR) service will add a route extending due north from Toledo to the mix. This north / south rail line (which will probably make use of existing track) will "cross the T" (intersect) its east / west (Dearborn / Ann Arbor) segment near Romulus / Metro Airport. This east / west T LINE segment could (and should) be extended east to MCS.
One more option should be considered: There's a proposal to close a portion of John C. Lodge Expressway (M-10), aka Aretha Franklin Freeway, south of its Fisher Freeway (I-75) interchange. If this happens, heavy-rail commuter trains could be hosted at a new downtown rail passenger terminal to be located in the freed-up space under Cobo Center (recently re-named TCF Center).
If trains terminate under the convention hall, a conditional stop at the parking garage (amid expected private-sector development in the area) would still be useful.
I've always thought of Michigan Central Station as a potential "destination station", not merely a stop on the way to someplace else. Despite thirty years of emptiness, the old monument still ranks as one of the world's most-famous / infamous landmarks.
When the main floor "public" areas of Michigan Central Station re-open in 2022, I hope they will serve as a gateway to the surrounding West Corktown and Mexicantown neighborhoods, stationed alongside a budding commuter rail link running between Detroit's central business district (CBD), MCS, and (eventually) the rest of southeastern Michigan.