11 June 2012
Preparations are under way to move the northern truss of a historic bridge in Vermont to allow the deck to be widened.
The bridge will be split lengthways to allow the northern truss to be moved about 3.8m so that new steelwork can be installed to create a wider structure.
Above: Staging and temporary wood bridge deck have been erected for worker access when disconnecting the north truss prior to widening. The bracing across the top will have temporary supports until the north truss is reconnected.
The widening is being carried out by the design-build contractor Harrison & Burrowes Bridge Constructors, with oversight by the USA's Vermont Agency of Transportation (VTrans), which owns the bridge. Finley is consultant for the scheme.
The Checkered House Bridge is the largest truss bridge in Vermont and represents a bridge type commonly used to replace bridges lost to the disastrous 1927 flood. As such, historic resource agencies wanted it to be preserved instead of building a new structure over the Winooski River.
Temporary bracing has been installed to support the bridge on the north side so that the truss can be disconnected. This involves the removal of bolts and rivets.
The truss will then be moved on rollers to its new location on abutments that were built last year. The move is expected to be carried out in the second half of this month in an operation that is due to take about five days.
New steel will then be put in place to reconnect the truss to the rest of the bridge.
From the side, the bridge will look as it always has since it was built by American Bridge in 1929. When looking along its length, the steelwork will no longer be symmetrical to ensure that the public can easily distinguish between new and original steelwork.