Tuesday, March 15, 2005

Apple #47: Covered Bridges


Recently, I went for a drive through the countryside and passed a covered bridge. I don't think I'd ever seen one of those in real life before. It looked kind of strange, like a long gray house with an empty, open road stretching out from either side of it. It made me think, "Why the heck did people put a roof over a bridge, anyway?"

Apparently, since covered bridges are not built any more, lots of people aren't sure why they were covered in the first place. But many reasons have been offered as possibilities:

  • To shelter travelers during storms (but if that were true, why not build a roof over the whole road?)
  • To provide refuge from Native Americans on the attack (ditto, and also unsettling, since people find covered bridges so quaint today)
  • To hide the sight of water from teams of oxen who would otherwise balk at going over it (were oxen used in all parts of the US where covered bridges were built?)
  • To level off the farmers' hayloads as they passed through (sounds too cute to be true)
  • To provide additional support to the truss structure (this sounds more plausible, though my rudimentary knowlege of bridge construction makes me skeptical that these bridges would need a full-fledged roof to hold them up)
  • To protect the wood decking of the bridge, which would otherwise rot from too much sun and rain exposure. It was easier to build a new roof than it was to build a new bridge. This explanation I believe.

With the advent of steel and iron at the turn of the 20th century, people stopped using wood for bridges, and the covered bridge became obsolete.

States where you can still see covered bridges:

  • Maine
  • New Hampshire
  • Vermont
  • Connecticut
  • New York
  • Massachusetts
  • Virginia
  • Georgia
  • Alabama
  • Tennessee
  • Pennsylvania
  • Ohio
  • Michigan
  • Indiana
  • Illinois
  • Wisconsin
  • Iowa
  • Oregon
  • California
  • Nova Scotia, Canada

If anybody's an engineer and knows something about bridges and can shed additional light on this subject, please ring in. For your convenience, I'm going to open up the comments so that anyone can post one -- having your own blog is no longer necessary.

Ozaukee County, Wisconsin
History of the Covered Bridge (photo source, too)
Covered Bridges in Oregon (includes a very helpful explanation of various types of trusses. And this useful, authoritative page was made by two Oregon high schoolers. Go Springfield!)
Vermont's Covered Bridges
National Society for the Preservation of Covered Bridges

1 comment:

  1. I have nothing to add from an engineering standpoint, but would like to include a link to the covered bridge of my youth, just down the hill from my grandparent's house in Lowell, Michigan. My brothers and I used to climb up inside the bridge, stick our heads out just under the roof, and spit. Depending on the strength of the wind that day, the spit would curve a little, or curve a lot after it got beyond the bottom of the bridge.



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