Actually on the South/North part it really is a tunnel. Only opens up to a gallery on the West/East part. Also there are some side arms to it that also qualify as tunnels, one underneath/parallel to Michigan avenue. Another tunnel would be the dig underneath the post office at the end/beginning of the Ike.
You could roar around the underground parking lots under Grant Park / Millennium Park in downtown Chicago. You could probably go in, roll the windows down, put a few miles on, tour every single parking aisle, and generally have your ears ringing for some time thereafter.
Of course, Chicago has miles and miles of tunnels underneath, just not many are accessible to cars. Most were made decades ago to shuttle coal, rolls of newsprint, etc. around and not create eyesores on the "surface" streets. Some of these tunnels, and others contain subways, communication cables, and other utilities. In 1992, workers digging holes in the Chicago River riverbed punctured one such tunnel, causing flooding in the lower levels of many downtown buildings. (Also that year, one of the famous draw bridges over the Chicago River, broke (lost the counterweight), flinging the road portion skyward.) Chicago is probably the only city that can brag that its rivers leak and its bridges fall up.
About 25-30 yrs ago I had a building at what is now called North Pier. In the lower lever were the tunnels you speak of, and the train tracks that were used for hauling heating coal etc. I loved going down there, as it was like stepping back 100 yrs in time (I might add, it was a bit spooky too).
I would say the best is lower wacker drive. Drive your car for a bit, get the TUBI nice and hot, it sounds better then... On lower wacker at night, minimal traffic, you can get up to about 40-50 MPH, right around that 3500 RPM mark to where the TUBI resognates the best and loudest. This will reverbarate all over the walls and cement on lower wacker, the sound is about ten times louder than in open air... HAH! Just becareful, you might find weak spots in the cement and cause a cave in.... I can't wait to do that.... ~
I remember going through "Hubbards Cave" (the enclosed portion of the Kennedy where it enters the north/south downtown leg) at a fairly "brisk" pace very late one night in the Dino with the roof off. There was no other traffic, and it was quite an acoustic treat. I think there is something about the geometry of the wall curvature, together with the glazed masonry wall surface that reflects and focuses the sound, creating standing waves at a certain "sweet spot". Interestingly, it works going in one direction, but not the other.
If all else fails, Rip through Mc Cormick place, we use to bring the cars there for vette fest (when held there, FYI its in rosemont this weekend). Its the tube where you walk from 31st exit to soliders field. Great for hearing pipes.. Nothing better than a 427 with side pipes half throttle down there. Awesomely Ear Piercing.. David
