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A refined Analysis of the Bartonsville Covered Bridge
Town Lattice Truss Completed.
By Philiip C. Pierce, P.E.
October 7, 2000 - I sent out my final report on the refined analysis of the Bartonsville
Covered Bridge last week and I have talked to the owner of the bridge and my client: the Town of
Rockingham. I also sent a copy of the report to the VAOT and have talked to them.* * * * *
The Town Lattice trusses at Bartonsville were
found to have suspect strength as a result of the Statewide Study, yet that work was based on a
very cursory analysis. The Study could not fund a thorough analysis of all 75 bridges - hence the
more simplified approach. The bridge has been posted at 3 tons since the Study (See Editors note
I have concluded, after exhaustive work, that I
am willing to increase the capacity to 17 tons for permit vehicles. According to state practice, the
bridge would still be limited to a posting of 16,000 pounds as a consequence of having a timber
floor. In my opinion, this is good news for Rockingham, and they agree.
My work has included the preparation of a
three dimensional, finite element computer model and has included field testing to verify the
results of the computer simulation.
While being similar to work done at the Brown,
Paper Mill, and Hopkins covered bridges, the analysis work has continued to evolve further into
the realm of unknowns with the bottom chord/lattice connections (in my opinion, these
connections are the key to the analysis of a Town Lattice truss).
I believe this work has pushed the envelope and
is getting closer to quantifying the "hidden reserve" of these bridges. More could be done, but I
ran out of time and money in this assignment. More efforts will hopefully follow on another
While I am in no way able (or motivated) to
speak for the VAOT about the ramifications of this work, I believe that the several other Town
Lattice bridges, found to have similar suspect capacity as a result of the Study, may benefit from
such an investigation. It is not cheap and takes a lot of work, but raising the capacity without
doing any field work is attractive.
I hope to discuss the results of my work with
VAOT shortly. It may generate interest in tackling some of the other bridges in a similar
Mr. Pierce owns and operates Phillip C. Pierce, P. E., a consulting engineering practice
specializing in covered bridges. Mr. Pierce has over 27 years of experience with diverse bridge
and highway engineering assignments while employed within other consulting engineer firms.
Editors note - The Statewide Study referenced above alludes to the Long-Range Planning
Study of Town-Owned Covered Bridges. This Study was sponsored by the Vermont Agency of
Transportation and completed by a consulting engineering team led by McFarland-Johnson, Inc.,
of Binghamton, New York. Mr. Pierce served as the Project Manager for the Study. The focus of
the Study was to develop a long-range plan for preservation of all of the bridges for the indefinite
The Study included an exhaustive
evaluation of all aspects of the bridge, including current and future traffic needs, as well as an
evaluation of the structural condition and needs of the bridge. Five preservation plans were
investigated at each bridge -- from keeping the bridge open to moderate traffic to rehabilitation of
the bridge or constructing a bypass structure if the covered bridge was found to be unable to
economically and/or safely support the traffic needs. No covered bridges were to be destroyed --
all to be preserved whether able to remain open to traffic or not.
The Study was completed in 1995 and
included seventy-five covered bridges and culminated in a report for each bridge which was
provided to its Town owner to help them decide which preservation action to pursue for the
During the course of the survey, some
of the bridges were found to be theoretically unsafe, in which case traffic weight restrictions were
recommended until such time as more extensive engineering evaluation was possible. The
Bartonsville Covered Bridge was one such structure. Hence, the work reported on herein, was
sponsored by the Town of Rockingham as a result of the early finding of suspect strength. Mr.
Pierce conducted the work under contract to the Town.
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Joe Nelson, P.O Box 267, Jericho, VT 05465-0267
This file posted March 13, 2001, revised April 26, 2006