Braun Intertec has been retained to assist in the replacement of the great Four Bears Bridge -- a mile-long, three-span steel truss structure.

Originally built in 1933, the bridge crosses North Dakota’s famous Lake Sakakawea in the northwestern corner of the Fort Berthold Reservation.

Challenges

The bridge was moved to its current location in 1952. Because it was done in November, when weather in the area is unpredictable, work continued 24 hours a day, six days a week.

The structure has only a 20-foot curb-to-curb width, resulting in just one 10-foot lane for traffic in each direction -- with no shoulders. Replacing the bridge will improve access and safety through the area.

Solutions

To determine the bridge foundation type and size, we are performing soil borings on the lake. This involves placing a drill rig on a barge and advancing borings through 60 feet of water and 240 feet of soil.

The bridge replacement is estimated at $43.2 million, and will be funded through a combination of $35 million in federal funds and $8.2 million from the State of North Dakota.

The project is sponsored by the North Dakota Department of Transportation and the Mandan, Hidatsa and Arikara Nations. Construction is expected to be completed in the Spring of 2006.