V.A.O.T. Historic Bridge Committee
Proceedings
Historic Covered Bridge Committee Notes from meeting of February 14, 2002
for:
WILLIAMSVILLE COVERED BRIDGE (NO. 17), NEWFANE
BHF 0106(4)S
Committee members in attendance: J. B. McCarthy, David Hoyne, Warren Tripp, Bob
McCullough, Eric Gilbertson, Nancy Boone, Scott Newman and Sue Scribner. Project Manager
Roger Whitcomb and Project Engineer Todd Sumner were also in attendance as was Joe Nelson
representing the Vermont Covered Bridge Society and Michael Canavan from the Federal
Highway Administration.
This meeting was a follow-up to the last meeting held on November 26, 2001 where it was
agreed that Scott Newman would further pursue whether it might be possible to consider
installing glulam beams underneath the structure, considering approach grade and hydraulics.
Scott presented some Power-Point slides where 5-foot deep glulam beams installed
underneath the structure had been superimposed. This demonstrated that, with the present
approach grade, no impacts would be made below the Q100 level. It was questioned whether it
might be preferable to install steel beams underneath as they would not need to be as deep and
could be concealed by extending the siding. Discussion ensued relative to steel beams being more
flexible than wood with different deflections resulting. The properties of glulam are much more
compatible with wood than steel. The likely impact on the abutments was discussed. Both are
laid-up stone and at one end in particular, a fair amount of stone would need to be removed to
accommodate auxiliary support beams under the structure. It was agreed that the following three
alternatives seem most reasonable for consideration:
- Remove the 8" high glulam beams currently in place, perform minimal but necessary repairs/
replacement of members, and then use glulam beams underneath the structure as a supplemental
system. Much of the structure has had changes, reinforcements, etc. made to date and much of
this would remain.
- Remove the 8" high glulam beams currently in place and use glulam beams underneath the
structure as a supplemental system but strive for an in-kind (same dimension, species and joinery)
replacement of deteriorated members. It is recognized that a significant percentage of the
members may require replacement but replicating the original engineering and craftsmanship is the
objective.
- Replace most, and possibly all, of the existing members with new timber of larger size (and
possibly species) to accommodate the desired loadings. No auxiliary support system would be
used.
Discussion was suspended to discuss another covered bridge that was originally scheduled
for this meeting. While available time was short, it was suggested at the end of the meeting that a
vote be taken by those present on their preference of the above 3 options. All but 2 present voted
for Option 2 above. It was agreed by those with the dissenting votes that direction could be
provided to the Project Manager to move forward with Option 2. J. B. McCarthy, the Structures
Program Manager, expressed possible concerns with the costs that might be associated with
Option 2. We agreed that it would be left that the Committee recommendation will be to move
forward with Option 2, but that if the Project Manager, during the course of project development,
developed cost estimates that in his opinion render this option unreasonable, he will request
another meeting of the Committee.
Respectfully submitted, Susan Scribner
Return to top
|