Vermont Agency of Transportation
Historic Covered Bridge Committee Meeting
November 18, 2020
2:00 – 3:00 PM
(This Meeting was held via MS Teams due to COVID 19 virus)

Attendance:

• • VTrans Structures Section:
    • Kristin Higgins – Structures Program
    • J. B. McCarthy – Bridge Preservation Engineer
    • Andrew Lemieux – Bridge Design Engineer
  • VTrans Asset Management:
    • Pam Thurber – Bridge Management Engineer
  • VTrans Environmental Section:
    • Judith Ehrlich
    • Kyle Obenauer
  • Vermont Covered Bridge Society:
    • John Weaver
  • State Historic Preservation Office:
    • Laura Trieschmann
    • Jamie Duggan
    • Elizabeth Peebles
  • Special Consultants:
    • Bob McCullough
    • Eric Gilbertson
  • Engineering Design Consultant VHB:
    • Evan Detrick – Project Manger
    • Jason Keener – Design Engineer
    •  

• Projects

• Wolcott Fisher Covered Bridge:

  The Wolcott Covered Railroad Bridge has been programmed for a project as part of the conversion of the Lamoille Valley RR into the Lamoille Valley Rail Trail. The project is being managed in the Agency by Joel Perrigo of the Municipal Assistance Bureau(MAB) and VHB is the design consultant with Evan Detrick serving as the project manager.

  Evan Detrick and Jason Keener of VHB gave a powerpoint presentation outlining the design issues that are being considered for the covered bridge.

• History:

  This covered bridge was originally constructed in 1908 by the Boston and Maine RR and is a 103.5 ft long double lattice truss and carried train traffic until the 1960s. The bridge (or maybe the floor system in particular) was in poor condition in the mid-1960s and facing replacement with a new steel truss bridge. In 1968 the State of Vermont assisted in funding a project to replace the existing floor system with a four steel girders and new ties to carry the live load of the trains. A timber pier pile group was constructed in the Lamoille River creating two simple spans (42-51ft). The covered bridge trusses, siding and roof were left in place to carry their own weight along with snow and wind loading. The State of Vermont purchased the entire rail line in 1973. The bridge carried rail traffic into the 1990s under lease to several different railroad operators. Severe flooding in 1995 and 1997 damaged much of the line such that it was not profitable to repair for rail traffic. In 2002 the State of Vermont let a contract to remove the ties and track to prepare for this line to be converted to the Lamoille Valley Rail Trail. Currently several segments to develop this trail are under design including this section from Hardwick to Morrisville which includes the Fisher Covered Bridge.

  The State of Vermont, Division for Historic Preservation as owner of this structure since 1968, would like to stress the architectural and engineering significance of this bridge and is committed to be an active partner with VTrans in support the new use of this bridge on the LVRT.

  The following is a summary of proposed work for this covered bridge to be opened to the public as part of the Lamoille Valley Rail Trail:

• Existing Trusses and Roof System:

  The existing trusses and roof system have been inspected and are in good condition to support their own weight and anticipated loads. A more in-depth inspection is pending on the roof framing and roof condition. No work is currently planned on the trusses or roof. It was suggested that a fire retardant and insecticide be applied to all of the trusses.

• Existing railroad rails and ties:

  There are still railroad rails (main rails and guard rail) present in the bridge and for a distance off each end. There is a strong desire to keep the rails on the bridge with the installation of new ties and deck system constructed above the rails to support the bike path and snowmobiles including a groomer (H10 loading). There was a discussion around keeping the rails visible at the surface of the new deck so that these rails would be visible to the public. However, there was concern about the unevenness of the surface and the potential hazard to bicyclists. The current proposal is to construct the new riding surface of above the rails which will be re-installed on new ties. A rail line pattern will be developed on the new riding surface indicating the location of the rails just below. Possibly using a different type of wood for the rail location can be considered?

  There is also a desire to keep the approach railroad rails in place. It will be necessary to bury these rails in the new trail bed material.

• Bridge Railing:

  A timber plank railing is being proposed for use inside the bridge. There was discussion about using untreated hemlock or other appropriated untreated lumber for this railing. VHB will further investigate and report at the next meeting. There was discussion about the type of screening to use between the horizontal planks. Options ranged from black poly-coated chain-link, welded wire mesh or timber spindles. It was mentioned that a wire mesh may provide a better view of the covered bridge portion while provide the safety needed.

  The rehabilitated Highgate Lenticular Truss Bridge has a railing that may be applicable for use on this bridge.

• Trail Approaches to the Bridge:

  Several alternatives were discussed relative to the trail approach to the bridge. Proposals ranged from splitter islands, to round-a-bouts to a rail end of line bumper. These alternatives will be further studied and presented later on.

• East Abutment:

  The east abutment was originally construct of laid up stones. The river is alignment is such that this abutment is located on the inside of the flow. A new concrete bridge seat cap and backwall was constructed when the bridge was modified in 1968. The project proposes to reconstruct the concrete bridge seat cap and backwall as the bearing cap appears to be delaminating. The remainder of the laid-up stone abutment appears to be in good condition.

• West Abutment:

  The west abutment was also originally constructed with laid up stone however, at some point in the past most of the exposed stem was faced with concrete including a knee wall at the base. The knee wall and lower potions of the facing are in poor condition. It appears ASR and freeze thaw issues have been the reason for the current poor condition of this facing. Possibly ASR testing should be considered? There is no definitive understanding as to why this abutment was faced with concrete other than potential damage to the laid up stone abutment from stream flow as this abutment is located on the outside curve of the stream and most probably takes the brunt of stream flow, ice and debris damage. There was discussion about how much of this concrete facing to remove and replace with a desire to expose more of the existing stone abutment especially in the upper portions below the bridge seat.

  There are a set of steps just off the west end of the bridge that connect to the parking area. These step are in need of repair, replacement or relocation as part of this project. VDHP is not concerned with the disposition these step as they are not original. VHB in conjunction with the MAB will propose a solution for these steps.

• Schedule:

  This project is funded with 80% federal and 20%state funds. Construction for this segment is schedule to begin in 2021.

  VDHP and VTrans need to explore an on-going maintenance plan for this bridge rather than leaving it up to a third party (VST or local group).

  VHB will develop and present further details at a future meeting.

  The meeting adjourned at 3:30 PM.