Backtalk - 03/20/2008

The Bay City Walking Dredge is the last one remaining in the U.S. of some 145 walking machines. The dredge was used to construct a portion of U.S. 41, called the Tamiami Trail, that connects Tampa with Miami through the Everglades and Big Cypress Swamp. of Bay City, Mich., the dredge had a unique propulsion design that let it handle drainage problems in wetlands environments. The machine dug a canal to provide rock fill for roadbed drainage for the road. The dredge, running on a 50-hp Charter internal-combustion engine, moved over rough, swampy, and slippery ground and through close-cut stumps, something that was difficult for other earth excavators. The walking mechanism was patented by Vincent G. Anderson, Thief River Falls, Minn., on July 2, 1918. According to the , Fall 1986, the first walker was designed by Albert N. Cross of Grand Rapids, Wis., in 1902. His design was modified in 1916 by Carl F. Wilson at Bay City in a form similar to Anderson’s patent. Wilson’s walker consisted of identical pairs of 30-ft bridge frames and weight-supporting runners on each s ide of the dredge. The bridge frame eased forward along the ground with the weight of the frame s moving from the corner runners to intermediary runners, using hoists and the motion of the bucket, until the corner pads could be repositioned. Once relieved of its load, the intermediary runners would be drawn forward and repositioned for another step. Each step covered 5 to 8 ft in 30 sec. The machine could be turned and backed up and required one operator and helper, which was one less than dredges on portable tracks. Dredges followed drilling rigs, which bored holes into limestone. The holes were then filled with cypress posts and dynamite that were electrically detonated. The world’s largest rubbish