Thursday, October 26, 2017

BNSF/BN/NP Bridge over Missouri River at Bismarck, ND

(Bridge Hunter, no Historic Bridges, John A. Weeks III, 3D Satellite)

Built in 1905 with the granite piers of an 1882 bridge. BNSF plans to replace this bridge.

John A. Weeks III
This photo shows the angle on the upstream side of the piers to help lift and break the ice flows to protect the piers.
Street View
From Bridge Hunter

Based on a paper written by Ed Murphy of the ND Geological Survey, the railroad (first Northern Pacific, and now BNSF), have had endless problems with the eastern pier of the High Bridge. Just after completion, the east pier began shifting towards the Missouri River at a rate of 3 to 3-1/2 inches per year. A number of repairs were attempted, but none seemed to work. In 1898, the pier was dug out and moved back onto a larger foundation. By 1902, the pier was already 4 inches off center. After further investigation, it was suspected that the city water reservoir located on a hill above the railroad track was leaking large amounts of water, causing the entire hillside to slide towards the river. The NP built a tunnel under the area to try to drain the water, but the pier continued to move. More projects were completed in 1918, 1923, and 1940 to try to slow down the landslide. In 1951, the NP undertook a major project to cut down the hill and regrade the area. This helped the situation by slowing down the movement to 1/3 of an inch per year, but did not stop the movement. [John Weeks]

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