Typically, covered bridges are structures with longitudinal timber-trusses which form the bridge's backbone. Some were built as railway bridges, using very heavy timbers and doubled up lattice work. They tend to be in isolated places, making them vulnerable to vandalism and arson.
Europe The oldest surviving truss bridge in the world is the
Kapellbrücke in Switzerland, first built in the 1300s. Modern-style timber truss bridges were pioneered in
Switzerland in the mid-1700s. Germany has 70 surviving historic wooden covered bridges. • The
Holzbrücke Bad Säckingen spans the river
Rhine from
Bad Säckingen, Germany, to
Stein, Switzerland. It was first built before 1272, and has been destroyed and rebuilt many times. • Switzerland has many timber covered bridges, including
Kapellbrücke,
Spreuer Bridge, and
Neubrügg. • The
Ponte Coperto in
Pavia is a stone and brick arch bridge over the
Ticino River in Pavia, Italy. The previous bridge, dating from 1354 (itself a replacement for a
Roman construction), was heavily damaged by
Allied bombing in 1945. A debate on whether to fix or replace it ended when the bridge partially collapsed in 1947, requiring new construction, which began in 1949.
North America Most bridges were built to cross streams, and the majority had just a single
span. Virtually all contained a single lane. A few two-lane bridges were built, having a third, central truss. which enabled him to design stronger bridges with fewer materials.
United States About 14,000 covered bridges have been built in the United States, mostly in the years 1825 to 1875. However, most other early examples of covered bridges do not appear until the 1820s. Extant bridges from that decade include
New York's
Hyde Hall Bridge and
Pennsylvania's
Hassenplug Bridge, both built in 1825, and the
Haverhill–Bath Covered Bridge and the
Roberts Covered Bridge, in
New Hampshire and
Ohio respectively, both built in 1829. The longest, historical covered bridges remaining in the United States are the
Cornish–Windsor Bridge, spanning the Connecticut River between New Hampshire and Vermont, and
Medora Bridge, spanning the East Fork of the White River in Indiana. Both lay some claim to the superlative depending upon how the length is measured. The vast majority of America's remaining covered bridges can be found in the eastern states with the notable exception of
Oregon, which possesses a collection of around fifty. Among western states, Oregon's covered bridges remain popular because of the state's many waterways and ample supply of lumber, as well as their resemblance to the historic covered wagons synonymous with Oregon's territorial history. In the mid-19th century, the use of cheaper
wrought iron and
cast iron led to metal rather than timber trusses. Metal structures did not need protection from the elements, so they no longer needed to be covered. The bridges also became obsolete because most were single-lane, had low width and height clearances, and could not support the heavy loads of modern traffic. mostly in eastern and northern states. The 2021
World Guide to Covered Bridges lists 840 covered bridges in the U.S., although it states that only 670 of those were standing when the 1959 edition was published. The tallest (35 feet high), built in 1892, is the
Felton Covered Bridge, just north of
Santa Cruz, California. In 1900,
Quebec had an estimated 1,000 covered bridges. Relative to the rest of North America, Quebec was late in building covered bridges, with the busiest decade for construction being the 1930s. Initially, the designs were varied, but around 1905, the design was standardised to the
Town québécois, a variant on the
lattice truss patented by
Ithiel Town in 1820. The designer is unknown. About 500 of these were built in the first half of the 20th century. In Quebec covered bridges were sometimes known as
pont rouges (red bridges) because of their typical colour. Ontario has just two remaining covered bridges, the
West Montrose Covered Bridge and the very short
covered bridge in Latchford. == Roofed bridges==