(Abandoned TCRT /NSP Power Tunnel)
There are many active and abandoned tunnels carved into the soft sandstone along the Mississipi River. Several of these date to the time of the Twin Cities Rapid Transit Company, which operated streetcars throughout the Twin Cities. The company's central power plant was located on the East Bank below St. Anthony Falls, and a hydrolelctric plant was also located nearby. Tunnels exist in a number of locations, both near the plant and farther afield, most of them being only short single stretches of passage with no branches, but a few with branches and shafts. Almost every TCRT tunnel exhibits the same iron arch cable supports, which helps identify such systems if one is encountered by surprise. The "Batcave" is such a tunnel, but with the added bonus that it intersects an apparently natural cave passage. It is likely that the natural cave is in fact erosional overbreakage above the North Minneapolis Tunnel, a large sewer interceptor built in the late 1800s. Such overbreakage occurs when excavated tunnels are lined with brick or stone hallways smaller than the original excavation, leaving a void space above the lining which can be enlarged by water and collapse. In some cases these voids connect to interesting things, but in the case of the batcave, it reaches a dead end at a rock wall behind which can be heard rushing water or sewage. The TCRT tunnel has been re-used sometime recently by the Northern States Power company, but was later re-abandoned. It is currently occupied by dead high-voltage power lines (but don't quote me on that if you lick one and it turns out to be live).
While much of the tunnel is bare sandstone, some parts are lined with cinderblock. The sandstone sections tend to migrate upwards as the cieling erodes and fills the floor with fine sand. Parts of the tunnel show evidence of flooding and lots of trash, especially 1980s style pop bottles and cans, probably from NSP workers or hobos.
The modern cable used to enter through a vault chamber and exit through a hole in the cieling at the far end of the tunnel. The power lines for TCRT streetcars likely entered through the mouth of the tunnel and passed up through the same hole to a TRCT substation or switching station.
The natural cave, and a muddy section. And to think some locals made fun of my Alaska fishing boots...
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