Why are Covered Bridges Covered?

On Friday touring thru Vermont we stopped at a few of the 104 covered bridges that still exist in that state. OK, so the first question I get is the obvious one...Why are they covered? Do I actually know this? No. I actually never thought to ask that question myself! So I give it my best guess....they were covered to protect the bridge floor and the people crossing it, from the elements.

When I got back to my room I googled "why are wooden covered bridges covered?" Turns out they are not covered to protect the people or the flooring. The people would get rained on or snowed on before and after the bridge so that doesn't make sense, and the floor is relatively inexpensive to replace when needed and in fact the bridge tender would usually keep the floor of the bridge covered with snow to allow sleighs to get accross.

They were covered to protect the structural components-the trusses- which were made of heavy timbers and much more expensive to replace. If the trusses fell apart the bridge would fall. An unprotected wooden bridge would last maybe 10 years, a covered one will last for centuries.

Timothy Palmer built the first one in Philadelphia between 1800-1804. Over time there have been something like 10,000 covered wooden bridges built but today fewer than 800 still stand.

The dwindling number is not due to weather conditions but to "progress"....heavy traffic and heavy trucks, and also to teenagers burning them down for fun.

So that's the long and short of it. I took my newly acquired information onto the bus this morning and explained why indeed covered bridges are covered.

I can't wait till next week when they ask me the same question, I'll be ready....of course they probably won't ask. But I will tell them anyway.