1934,1955+2005 Four Bears Bridges over Lake Sakakawea on Missouri River near New Town, ND

(no Bridge Hunter; no Historic Bridges; John A. Weeks III; Satellite)

The continuous truss for this bridge was first built in 1934 40 miles down river of New Town at the City of Elbowood. When the Garrison Dam was built in 1955, the big truss was floated up the river to be used in this bridge. [JohnWeeks]

GhostsOfNorthDakota_bridge, this webpage contains several photos showing the construction of the piers.

NDtourism
"Design honors 19 tribal chiefs of the Mandan, Hidatsa and Arikara Indian tribes. It is the longest bridge in North Dakota, spanning nearly 1 mile."

 

New Town was built to provide new homes for the people that were displaced by the creation of Lake Sakakawea, which was created by the Garrison Dam.

This photo includes the construction of the replacement bridge.

GhostsOfNorthDakota_sanish

 

JohnWeeks
"The bridge was to be a precast segmented concrete box girder that was held together by post-tensioned cables that run though the bridge structure. The bridge required 482 of these precast segments, to be used to build 13 spans of 316 feet each, and 2 spans of 196 feet each, for an overall bridge length of 4,500 feet. The piers are interesting on the new bridge. Ice is a big factor, and some extreme forces could potentially hit the bridge if the ice on the lake goes out during high water in the spring. To protect against these forces, cone-shaped concrete piers 39 feet in diameter were built. The side walls of the cones are set at 65-degrees, which will deflect ice upwards, reducing the stress on the piers. The piers are each supported by 13 or 14 pilings driving into the riverbed between 90 and 160 feet. The piers range from 45 feet to 73 feet, and the bridge ranges in thickness from 8 feet to 17 feet, placing the roadway as high as 90 feet above the water."

So did these display remnants come from a deck truss or from the big continuous truss?

Street View, Nov 2021

'Today (Nov 11, 2024), I learned about two truss bridges because they had been destroyed. The other one was the Madawaska-Edmundston International Bridge.

Carl Bolander & Sons posted seven photos with the comment:

🟢 Four Bears Bridge Project - Part 1 

In 2005, Bolander was contracted to demolish and remove the Four Bears Bridge over the Missouri River near New Town, North Dakota. This included the existing 4,300 foot long steel box truss bridge and the concrete pier foundations. 

Key project highlights include:

🟢 Environmental Safety: Before demolition, our team meticulously inspected the structural steel for loose lead paint, ensuring safe removal and disposal in compliance with environmental regulations.

🟢 Efficient Demolition: The concrete bridge deck was effectively dismantled using hydraulic breakers, with the rubble carefully loaded onto material barges for transport to a concrete recycling facility.

🟢 Innovative Techniques: We employed pre-torching and blasting methods for the structural steel truss members, allowing for efficient removal and recycling. The steel sections were expertly retrieved from the riverbed using cranes and a five-point grapple system.

🟢 Precision in Pier Demolition: Our team utilized excavators and drilled holes in the concrete piers to place explosives, bringing them down to the necessary elevation while minimizing environmental impact.

🟢 Habitat Restoration: Using sonar technology, we precisely placed concrete rubble from the demolition on the riverbed, transforming it into a new fish habitat.

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