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Poland Bridge Inspection Items Addressed by Alpine Construction Team

Cambridge Junction, August 24, 2004 - Jim Ligon and his team returned to the Poland Bridge this morning to address two items cited by the Vermont Agency of Transportation acceptance inspection: Voids in the abutments, and reinforcement of the Burr Arch bearing plates.
      The Alpine team will force Portland cement into the abutments to fill any voids found and back the four bearing plates with grout.
       Said Ligon in an email to this writer, "The bearing plates are 1" steel, with a large gusset welded in the center to accept the through bolts. The high heat produced during that welding process of thick steel made the large plates curl very slightly. That issue was addressed a year ago when the plates were delivered to the project, with no corrective action determined to be required. My interpretation of the conversation with Bill Flanders was that someone on the inspection team was concerned that the plates had bent due to the loading of the arch members."
       A last minute decision allowed the bridge to open for the planned July 4th opening ceremony and to remain open. Said William Flanders, VAOT Site Engineer in an email: "The area in question was reinforced by the installation of hardwood blocks. This installation facilitated the bridge to remain open while discussions occur as to a permanent solution."
Poland Bridge. Photo by Joe Nelson, August 24, 2004 Poland Bridge. Photo by Joe Nelson, August 24, 2004
A form is placed around each of the four bearing plates to facilitate the introduction of grout between the plates and the abutment face. This is to prevent further flexing of the plate due to loading of the arches. Photo by Joe Nelson, August 24, 2004 The bearing plate receives the end of the Burr Arch. The tab accepts a through-bolt securing the arch to the bearing plate. The bearing plate is mounted on the abutment with threaded studs embedded in the concrete. The void behind the inch-thick plate was temporarily filled with a piece of hardwood, now to be replaced with grout. Drawing by Joe Nelson, August 24, 2004
       Traffic was permitted with the stipulation that only one vehicle at a time would be allowed on the bridge and a sign with this regulation was posted. Unfortunately, bridge users are either ignoring the sign or interpreting it to mean "One way traffic at a time only." Cars are streaming across at close intervals. In one instance, a large pick-up truck and laden trailer closely followed by a passenger car were seen to cross.
       The bridge remained open while the Alpine team worked.

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Joe Nelson, P.O Box 267, Jericho, VT 05465-0267
This file posted August 26, 2004