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V.A.O.T. Historic Bridge Committee Proceedings

Historic Covered Bridge Committee Notes of June 23, 2005 for:


Present at Meeting:

  • Committee members:
    • J.B. McCarthy
    • Warren Tripp
    • Eric Gilbertson
    • Nancy Boone
    • Bob McCullough
    • Pam Thurber
    • Scott Newman
    • Sue Scribner
  • Also in attendance were:
    • Mr. Stephen Barrett, Public Works Director with the Town of Brattleboro
    • Joe Nelson representing the Vermont Covered Bridge Society
    • Michael Canavan from The Federal Highway Administration
    • VTrans project manager John Weaver

Project manager John Weaver provided an overview of the bridge and its current condition using photos to assist in his presentation. Preliminary plans have been developed and were provided.

  • Roof System: It is the intent to salvage the existing slate roof. It is in very good shape overall. The town, using the services of Neil Daniels, added new interior bracing for extra support. It is proposed that a new standing seam roof be added to the walkway portion only.
  • Truss System: The bottom lower chord is a "conglomerate of bits and pieces" bolted together, likely in the 1980's. Some of the sections are quite short. Some sistering will be necessary and it is proposed that trunnels be used for connections so that the sisters are installed in a traditional manner. It is proposed that a new bottom chord be installed of glulam - it would be very close to the existing dimensions - with new blocking at x-brace connections. Extra support is proposed for the attached walkway.
  • Floor System: No changes to the floorbeams. The deck and running boards are currently very worn down. A new nail lam deck is proposed with runner. Curbing is shown on the plans to channelize traffic. The town questioned whether the runner planks should be full width as proposed or as existing to hopefully slow down traffic.
  • Substructure: Abutments are in good shape.
  • General: It is proposed that fire retardant and insecticide be applied both inside and out.
  • General Discussion:
    • The amount of sistering is unknown at this time. John is estimating 5 lattices but could be more. The committee in general would like to see this minimized. In order to get adequate connections, if a new glu-lam bottom chord is not installed, John Weaver expects that more sistering would be required. A point of consideration is that if more sistering occurs, it will add a significant amount of dead load which is already a factor due to the weight of the existing slate roof.
    • It was asked if there is a system laid out for determining if sistering will be required for individual members. The expectation is that the project manager, the VTrans Historic Preservation Officer, a representative from FHWA and the resident engineer, at a minimum, will inspect the lattices once the bottom chord is removed and mutually decide which will need sistering.
    • It was suggested that cautionary notes be added to the project plans advising that sistering will be minimized and how the determination will be made.
    • It was asked if Douglas Fir could be used full length in place of the proposed glu-lam for the lower bottom chord. John Weaver noted it is hard to dimension properly at that length (the bridge is almost 85' long) and there are problems with warping. It is not recommended. It was noted that installation of the glu-lam chord could be reversible if other material options present themselves in the future and is beneficial as less sistering will likely be required.
    • Finally, it was noted in general how unique this structure is due to its visible urban setting.

A motion was made to move forward with the details shown in the plans as provided by John Weaver with cautionary notes as discussed and that it be required that the VTrans Historic Preservation Officer be at the field meeting to confirm which lattice members need sistering. The motion was seconded and unanimously passed.

Respectfully submitted,

Susan Scribner

Chair, Historic Covered Bridge Committee

[This article was originally posted July 14, 2005]

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