Slate Covered Bridge, Westport New Hampshire
Located on a road parallel to NH Route 10, the Slate Covered Bridge is no longer a vital highway river crossing, although a great convenience for residents of the Westport section of Swanzey. Its close proximity to the state highway on a surfaced secondary road makes it a popular attraction and easily accessible regional historical, artistic, and technological resource.
The Slate Covered Bridge in particular well illustrates the Town Truss construction designed and patented in 1820 by Ithiel Town, a New Haven, Connecticut, architect and builder.
The first truly American covered bridge design, it is characterized by a web of heavy planks crisscrossed at an angle of 45 degrees to 60 degrees, resembling a lattice, fastened together with wooden pins or trunnels at each intersection. It is an especially picturesque design, particularly in a well-proportioned structure such as the Slate Covered Bridge, although it suffers from the engineering defect of being structurally indeterminate (i.e. The stresses in the truss members cannot be analyzed by traditional means.).
Bridge Description
Spanning the Ashuelot River on the state secondary highway system, originally a part of trunkline NH 10, near Westport village, this bridge is located just off the present NH Route 10.
Built in 1862, this single-span bridge 122 feet long and 17 feet wide occupies the site of earlier covered bridges, cost $1,850.64, and takes its name from that of an early neighboring family, rather than any construction detail. Although it probably retains much of its original appearance, many parts, including flooring, roof, and support beams, have been repaired or replaced. It has the unusual feature of four long iron turnbuckle rods to reinforce its Town lattice truss construction. A tin roof, replaced sheathing, and roadway "tracks" indicate repairs. Abutments are of split granite; the side walls of the bridge are fully sheathed.
The National Society for the Preservation of Covered Bridges World Guide to Covered Bridges number is 29-03-06, New Hampshire Department of Public Works and Highways number is 080/090.
Portal (1978)
