5/29/2006:
Great Plains dwellers have been moving great big things from one place to another for a long time--things like teepees, claim shanties, railroad depots, barns, and even grain elevators. At times whole towns were moved to new locations when anticipated rail lines failed to materialize. In recent years, many a historic home has been moved out of harms way—be it rising water, the wheels of “progress,” or the wrecking ball.
This day in 1898 was moving day for one of the heaviest structures ever moved across the prairie. OK…“Across the prairie” is a bit of an exaggeration—this thing only moved about two and a half feet. But still…getting it moving and getting it to stop in the right place involved expert engineering, dangerous work, and a measure of luck. According to the Bismarck Daily Tribune the weight of the thing was calculated at 9 million pounds.
Railroad engineers move very heavy things—that’s their stock in trade. But this move was a bold undertaking for Chief Engineer E. H. McHenry and crew. Their task was to move the concrete and granite pier that holds up the east span of the Northern Pacific bridge over the Missouri River. The structure rests on land—on the eastern slope, in Bismarck.
This is no small bridge. The Mighty Missouri was a major obstacle when the rails reached Bismarck from the east in 1873. Crossing the Red, the Sheyenne, and the James had been relatively routine. The rails stopped at Bismarck for nine years, except for temporary tracks laid on the river ice, until the bridge was completed in 1882. The delay was due in part to the railway’s financial problems, but the expense and the physical challenge of bridging the Missouri were contributing factors.
The east pier was problematic from the beginning. Though it rested on a 20-foot thick concrete foundation well below the surface of the ground, the giant structure was sliding toward the river at 3 to 4 inches per year. After futile attempts to stop the movement, engineers set out to excavate and modify the foundation and slide it back into position in 1898. Preparation for the big move lasted eight months.
On moving day—May 29th—the massive pier sat ready to move on a system of steel rails and rollers that had been inserted between the old and new foundations. All of this was down in a deep excavation. As pressure was applied with giant screws and levers, the pier began to move, but so did the earth on the west side of the excavation. As a great crack developed in the earth, work was stopped and the workmen scrambled out of the pit to safety.
Minutes later, the wall of the excavation caved in, falling against the west side of the pier. The Tribune reported, “For perhaps a second the ponderous granite cylinder trembled at the impact. Then there was a slight movement of the whole pier in a forward direction, and…then the huge stone structure slid forward at a speed which seemed impossible for so ponderous a mass…The entire pier shot forward grandly, majestically, smoothly upon its steel rollers…and then stopped dead upon the foundation…nature had assisted the work of the engineers…”
The move was an astonishing success, but didn’t totally solve the problem. According to Edward C. Murphy of the North Dakota Geological Survey, the east pier has continued to move over the years and additional countermeasures have been needed…but nothing so dramatic as 9 million pounds of granite moving majestically back to it’s proper place.
Written by Russell Ford-Dunker
Sources:
Murphy, Edward C. “Movement of the East Pier of the Northern Pacific Railway Bridge at Bismarck, N.D.” North Dakota Geological Survey. Retrieved from http://www.ndsu.edu/instruct/schwert/ndgs/bism_brg.htm
“Pier Is Moved” Bismarck Daily Tribune, 30 May 1898, p. 3.