mgk920 said:
That is an aspect of Milwaukee history that I have never heard of before. What else do you know about this never-completed subway?
During the 1920s, TMER&L built a grade-separated, double-track, private right-of-way rapid transit line through the west side of the city and suburbs. The new line replaced the previous in-street route, which zigged and zagged its way through the same territory. However, there was a gap between the downtown interurban terminal (the Public Sercie Building at 3rd and Michigan Streets) and the beginning of the rapid transit line (at roughly 8th Street between Clybourn Street and St. Paul Avenue) where interurbans had to navigate some right-hand turns and in-street running for the few blocks in between those points. The "subway" was planned to eliminate that stretch of street running by directly linking the PSB (which would get an underground platform/boarding area) to the rapid transit line. So the proposed subway was really just going to be a tunnel about five blocks in length.
The western end of the tunnel was actually partially built, between 8th and 7th Streets. This was next to the newly-built Transport Building, which was the transfer terminal for TM's freight service (later became Aldrich Chemical). Of course, the Great Depression prevented TM from ever completing the tunnel project, so interurbans had to continue zig-zagging those few blocks down the middle of the streets until they were ultimately discontinued in 1951. Up through then, the incomplete subway approach was used for car storage. All of this was eventually obliterated by the time the freeway interchange was put in during the late-1960s. And the rapid transit line through the West Side itself became the right-of-way for the I-94 freeway.
There are very few details known about how the eastern end of the subway would have been arranged beneath the PSB, had it ever gotten that far. It could have been a simple stub-ended arrangement, or perhaps an underground loop around the block. Another challenge would have been passing beneath street trackage of the North Shore Line (at 6th and Clybourn Streets) and the Milwaukee Road tracks coming out of Union Station (near 4th and Everett Streets). But it is likely the only stops interurbans would have made in the tunnel would be at the underground PSB terminal, since the tunnel was only five-blocks long...so it would not have been like the usual kind of subway we're familiar with.
Of course, if this "subway" could have been completed, it could have been a catalyst for addional interurban tunnels in Milwaukee. Perhaps it could have motivated TM and the City to build a tunnel to link the Public Service Building with the private right-of-way of the northern interurban line on the North Side of the city (which had to traverse a few miles on city streets instead). Such an operation would have probably behaved more like a traditional subway too, since it would have been a distance of a few miles and at least a few intermediate stops, rather than just a few blocks and no intermediate stops.