Owner and Client:
The Town of Rockingham, Vermont

Engineer:
Phillip C. Pierce, P.E.
Treadwell, NY

Project Description:

The Bartonsville Covered Bridge, built in 1870, has been restricted to vehicles of no more than 3 tons, since a preliminary assessment performed as part of a state-wide study of covered bridges in Vermont, conducted in the mid 1990s. The structure is supported by 151 foot Town Lattice trusses - the longest single-span in the state of Vermont. The trusses were constructed with only a single level of top chords, which significantly reduces the capacity of the structure, compared with more traditional Town Lattice trusses have two levels of chords on both the top and bottom.

The assignment included an in-depth analytical evaluation of the bridge to more accurately determine its live load capacity. A sophisticated finite-element computer simulation was performed to predict component forces and behavior under dead and live loading. Follow-up deflection measurements of the structure under the influence of known vehicular loading, as a comparison to computer predictions, were obtained as a means to validate the computer simulation. The evolutionary evaluation culminated in the determination that the capacity of the bridge could be set at 17 tons without rehabilitation. (Obviously the client was pleased with that result.) This increased capacity allows the structure to be used by school busses, emergency vehicles, and snow plows. A report was prepared to summarize the findings and identify proposed improvements to the structure.

The work was completed in 2000.