By: Lane Enterprises, Inc
Our first ever Service Life Project of the Year Award goes to Lane Enterprises for their impressive 1938 Plate Arch Rehabilitation.
This Minnesota DOT project provided for the rehabilitation of Bridge No. 5265 by adding additional side plates to the interior and exterior of the existing structure to preserve the historical value of the Minnesota Historic Roadside Development Structures Inventory bridge. Another feature of this historic preservation project included ensuring the granite-faced headwalls and lake boulder footings were well-preserved.
The steps taken to develop the preservation plan involved unearthing and cleaning the structure in order to make a complete evaluation of its condition. Once exposed the structure was examined and found to be in excellent condition apart from the bottom foot and a half of the legs on each side of the arch (i.e. the side plates).
The rehabilitation plan developed as a result of the evaluation included the application of an asphalt based fabric to the outer surfaces of the arch, prepping the interior legs for an application of a protective paint coating, and then sandwiching the legs with new reinforcement plates that were bolted together through the existing legs before finally securing the new plates to the foundation with new support angles.
Especially nostalgic were the original markings of the structure that indicated an Armco product dated March 19, 1938, in addition to the dated corrugation depth of 1.5 inches as compared to today’s standard two inch depth.