Covered bridge
The Cogan House Covered Bridge, Pennsylvania | |
| Ancestor | Truss bridge, others |
|---|---|
| Descendant | None |
| Carries | Pedestrians, livestock, vehicles |
| Span range | Short |
| Material | Typically wood beams with iron fittings and iron rods in tension |
| Movable | No |
| Design effort | Low |
| Falsework required | Determined by enclosed bridge structure, site conditions, and degree of prefabrication |
A covered bridge is a timber-truss bridge with a roof, decking, and siding, which in most covered bridges create an almost complete enclosure.[1] The purpose of the covering is to protect the wooden structural members from the weather. Uncovered wooden bridges typically have a lifespan of only 20 years because of the effects of rain and sun, but a covered bridge can last over 100 years.[2] In the United States, only about 1 in 10 survived the 20th century.[3] The relatively small number of surviving bridges is due to deliberate replacement, neglect, and the high cost of restoration.[4]
Surviving covered bridges often attract touristic attention due to their rarity, quaint appearance, and bucolic settings. Many are considered historic and have been the subject of historic preservation campaigns.
- ^ "Covered bridge". Encyclopædia Britannica. Retrieved 8 October 2012.
- ^ "Ohio's Vanishing Covered Bridges". Federal Highway Administration. Retrieved 8 January 2019.
- ^ "World Guide to Covered Bridges". National Center for Wood Transportation Structures. Retrieved 8 January 2019.
- ^ Ross, Robert J.; et al. (August 2012). "Use of Laser Scanning Technology to Obtain As-Built Records of Historic Covered Bridges" (PDF). U.S. Department of Agriculture. Research Paper FPL-RP-669. Retrieved 9 January 2019.