I ran across this spot while looking for a good place to
photograph the tunnels. Even though I've worked close to here I
didn't know it existed so I just had to put a cache there to share
the view with others.
The St. Clair River Tunnel was the first full-size submarine
tunnel built in North America. Prior to its completion railroads
had not been able to pass beneath rivers. This accomplishment was
only possible by combining three elements of tunnel construction:
the shield method of excavating, the cast iron tunnel lining, and
excavating in a compressed air environment. The St. Clair River
Tunnel is important in the history of engineering because it was
the world's first true test of the feasibility of constructing
railroad (and later vehicular) tunnels through the soft, porous
ground commonly found beneath rivers
The tunnel was completed in 1890 and operated for over 100 years
however the bore diameter of 19’ 10” could not handle larger
freight cars and a new tunnel, 27’ 6” in diameter was opened in
1994
There is no hint but the picture below was taken from the cache
location
