The scope of work here is to realign the roadway to remove a dangerous curve in the road, in this process we had to move one end of the 122′ long steel through truss approx. 18′ to a new pier that was built next to the old pier. This also required us to build a new abutment on the north end so the 70′ long pony truss would set on it and the new pier. The pony truss was picked up with a hydraulic crane, and set aside to have repairs done to it, and will be set back on its new foundations when all the new pier work is complete.
The through truss was a different story: First the south end was jacked up and the old stone abutment was removed and a new abutment was built under the structure, while the truss was supported 15′ above the existing ground for the new footing. After the new abutment was poured and cured the truss was set back down on the new abutment, but this time it was set on 3″ solid steel round pins, to allow the south end to rotate. Then the north end of the truss was jacked up and then let back down on a carrier beam that was setting on more 3″ solid steel round pins. An anchor post was attached to the new pier column, and the truss was pulled over to the new pier with a come-a-long inches at a time. While the north end, or pier end, was inched over to the new pier, the south end, or abutment end, was cabled to a Cat 322 excavator so it would just pivot, rather than roll off of the abutment.
The actual moving of the truss only took about 3-4 hours, but the preparation took a couple of weeks. We felt that this was the safest method to do this operation, because, except for when the abutment was being rebuilt the truss was never more than a few inches off of the concrete.
There were many changes from the original plans before this was accomplished. The original plans called for just relaying the stones in the abutment in the south end, but when we removed them, we found only one wall of stones, and they were cut into an existing rock ledge. This required us to go through a redesign of the abutment, but with the combined efforts of CLR, INDOT, WTH Engineering, and Farrarr/Garvey Engineering, the changes were made and progress was made.
A winter Iron bridge scene in Owen County Indiana