Sunday, July 3, 2011

Bridge Moving 101

Originally, the RecPath was slated to cross over two telephone pole bridges were built along Wesley Drive by Eagle Scouts a few years ago when the RecPath was just a hiking trail. During construction, we saw an opportunity to shift the RecPath alignment a bit in the field, and preserve some nice trees near the stream crossings. The contractors had never moved any bridges before, but they were game for it. Bill Dyer was able to be with them the day they moved the second bridge.

One of the timber bridges is shown with one of the trees that originally were slated to be cut down. The contractors (Pruzinsky & Sons & Fairview Tree Farm) placed steel plates over the streams to protect the stream bed, put gravel over the plates and used that crossing for all their heavy hauling.

Once the heavy machinery was back across the stream the larger excavator removed the steel plates and stone foundations were built where the plates had been.

Steel channels were placed under the bridges and the entire bridge was lifted over onto the new abutments. We weren't sure how well this would work because we didn't have any records when the scouts built the 8 foot wide by 20 foot long bridge. Trails volunteers scrambled that week to add extra floor beams and stiffen the bridges prior to the contractors reaching those crossings.

Everything went well and the contractors took the better part of a day to relocate each bridge.

A lot of care was taken to minimize disturbance of the stream bed, and to make the bridge abutments look as natural as possible. At this point all the heavy earthwork was done and the smaller equipment was placing the final surface of fine processed aggregate.

The steel plates were loaded into a truck and hauled up to the next work area. They really worked well to avoid disturbing the stream bed.

The contractors then worked on cleaning up the side slopes, placing stones, and a lot of wood chip mulch to stabilize all the disturbed areas.

Here is the finished bridge looking very natural and with a number of trees preserved along the stream. One of the good features of a Design-Build contract is that you have the flexibility to try things like this in the field. Good job by everybody involved.

2 comments:

  1. It seems the contractors have gone above and beyond on this entire project. Very nice work!

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    ReplyDelete