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CUMBERLAND LAKE & PITMAN CREEK BRIDGES

Difficult Foundations

This project involved the construction of 2 new steel girder bridges and concrete roadways adjacent to existing bridges. The challenge of providing the necessary equipment to this landlocked lake was accomplished by trucking to the site over 125 pontoon sections owned by Massman for assembly into crane barges and material barge.

The 6 new lake piers were constructed on two 11-foot diameter drilled shafts inside of 11.5-foot diameter permanent steel casing. The longest rock socket was 45 feet deep and was part of a 180-foot high drilled shaft. This rock socket drilling operation was successfully accomplished in spite of over 40 feet of lake level fluctuation.

On top of each pair of drilled shafts is an 11.5-foot high by 10-foot wide by 60-foot long strut. Next, two 10-foot diameter reinforced concrete columns are constructed an average of 80 feet. Each pier cap is 10 feet square and 80 feet long. The 85-foot wide concrete roadway is supported by seven rows of 8-foot tall steel girders.

The 8-foot tall steel girders were transported to the project by truck and then offloaded onto Massman barges for assembly into double rows of girders that were cross-braced together for stability during assembly and erection. The girders varied in length from 36 to 112 feet long with the largest single piece weighing up to 41 tons. The largest assembled double row of girders was 135 feet long and weighed up to 78 tons. The overall length of the bridge was 1406 feet.

The demolition of the existing 1,400-foot steel truss and concrete roadway on the Cumberland Lake project was accomplished by demolishing the roadway deck from above, blasting down the steel structure, blasting the existing concrete piers to below minimum lake levels and removing with barge-mounted cranes, the blasted steel and rebar pieces from the lake bottom.

Pulaski County, Kentucky