Comstock's Covered Bridge, East Hampton Connecticut
Comstock's Bridge is one of only three covered bridges left in Connecticut. Because they sheltered their supporting members from decay, covered bridges were once common throughout America, yet comparatively few are left. Although no longer used by traffic, Comstock's Bridge is located in a state-maintained picnic area, and is widely accessible.
The short 30' span which serves as an entrance ramp on the east bank is typical of construction before covered bridges, although it is not known that it precedes the main span. In this short section, the trusses themselves, the weight-bearing members, are protected by being encased in wooden planks, but the floor and the projecting braces which hold the floor's supports are all exposed. Most New England bridges were built like this until covered bridges with their greater protection became the norm.
Comstock's Bridge exhibits a revolutionary step in bridge building, the use of iron at a key structural point. Although it cannot be precisely dated, it apparently was there in 1868 and cannot have been built before 1840, when its truss design was invented. The Howe truss overcomes the chief defect of designs that used wooden uprights: under load, the joints between vertical, horizontal, and diagonal members tended to work loose. For the wooden uprights, Howe substituted adjustable iron tie rods, in essence binding the whole structure together with iron and thereby providing rigidity and security to the truss previously unknown. This also made building easier, since complicated joinery was made less critical. Howe's design became widely accepted, and Comstock's Bridge is an example of the many bridges built with this innovation, a step toward the structural iron bridge.
Although much of Comstock's Bridge is not original; the floors, siding, roof repair, and reconstruction have generally been thoughtful, ensuring the retention of the appearance of a typical covered bridge. More to the point, however, the main structural element, the truss, is as it was, and together with the shorter span, is an important artifact in documenting attempts to build stronger and more durable bridges.
Bridge Description
Comstock's Bridge spans the Salmon River at the boundary of Colchester and Easthampton, Connecticut. Originally part of the road to Middletown, the bridge is now the focal point of a wooded picnic area; the highway, Connecticut Route 16, now crosses the river a short distance downstream. The main span is a covered one-lane (about 12') wide bridge, 80' long and about 15' above the river, having plank sides, a moderately pitched roof, cedar shingles, and oval portals. Two square unglazed window openings have been cut into the sides, and wooden latticed gates prevent vehicular traffic.
The bridge is borne by a Howe truss, which combines crossed wooden diagonals with iron tie rods for uprights. The stringers are built up of thick lapped planks, and the floor, laid parallel to the bridge over a diagonally=planked sub-floor, is borne by joists reinforced with diagonal supports. The east pier of this Span is of dressed granite laid as regular ashlar, but the west abutment is of both granite and a mixed-stone mortared rubble, suggesting a later rebuilding of the abutment.
A second wooden span of 30' connects the east pier of the covered bridge with the eastern abutment, built of unmortared rubble, mostly flat stones. This shorter span is uncovered, exposing the floor and its bracing, which projects at an angle from the sides. However, the trusses are boxed in with vertical Planking, and topped with a peaked cap. The design of this part and the difference in the abutments suggest that this is a remnant of an earlier bridge, but this is conjecture.
Most alterations have been made necessary by wear and tear, but nevertheless, these have been extensive. In the 1920's a truck crashed through the floor, necessitating much repair. The Civilian Conservation Corps in the Thirties did a great deal of work on the bridge, installing the gates and windows as well as making important replacements, such as roof and floor supports, stringer sections, and siding, for which they used old barn boards. Some of the older, narrower siding may remain. Similar repairs, including a new cedar roof and spacers between the sides and the structural members, were made when the bridge was renovated as part of a park. At one point the truss was braced with steel plates at the joints.
(1975)
(1975)
