Tuesday, July 9, 2024

1916,1947 UP/C&NW+CPKC/Milwaukee Bridge over Mississippi River in St. Paul, MN

(no Bridge Hunter? no Historic Bridges; John A. Weeks IIISatellite)

This is one of the flood incidents of 2024.

According to a topo map and John Weeks, this is UP/C&NW/Minneapolis, St. Paul & Pacific (Omaha) and CPKC/Milwaukee Road. The locals refer to it as the Omaha bridge. A more official name is River Bridge #15. John explains that this structure was one of the original 15 bridges to span the Mississippi River. The first crossing here was built in 1869, and it was a wooden drawbridge.
River View, Aug 2016

A bobtail bridge always has a counterweight on the short end to balance the bridge over the pivot.
The bridge is 1,055' (322m) long with a navigation channel of 160' (49m).
"Despite a fair number of trains using this crossing, the bridge is maintained in an open position except when trains are using the bridge. The unusual feature of the swing span is that the pivot point is not in the middle of the bridge. Rather, the river section of the swing span is 185 feet [56m] long, while the other side is only 75 feet [23m] long. This feature is called an asymmetrical swing bridge [or bobtail bridge], and it is the only bridge like it on the Mississippi River.According to a local legend, once the bridge was erected, the owner of the land adjacent to the rail line objected to having the bridge swing over his land. To solve the problem, the railroad simply cut off that part of the bridge, and balanced it out with the large concrete slug that hangs off the back end of the swing span. The real reason for the non-symmetrical swing span is that the navigation channel is so close to the shore. The result is that half of the swing span would swing over dry land, so why span that dry land with expensive steel when cheap timber and cheap concrete would do the trick?
[John also describes the corporate history of the bridge.]

Another view of a normal river level.

Flood of 2024

Compare the height on the piers to the river view at the top of these notes.
19:31 video @ 6:46

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