Planning a trip to any of Ohio's 140 covered bridges? Here's what you need to know to fully appreciate and understand these historic treasures.

Planning a trip to any of Ohio's 140 covered bridges? Here's what you need to know to fully appreciate and understand these historic treasures.

Don't worry if you're not already an architectural genius; this will get you up to speed. Feel free to drop your newfound covered bridge knowledge on your fellow travelers to impress them. (Just make sure you get it right.)

It may seem obvious, but bridges are so covered mainly to protect it from weather and other outside forces. It's said that early-19th century builders quickly learned that a covered bridge lasted two or three times longer than an uncovered one, and judging by those who have survived for 150 years, their decisions seem to have paid off.

All covered bridges are primarily categorized by truss types. A truss is basically the connected framework, in this case of wooden or metal beams, that holds together the bridge.

Ever driven on a windy road through a lot of trees and come across a little bridge with the short, metal frame on each side? That's a truss. (Specifically, that's a pony truss, like what the Ponn "Humpback" Bridge in Vinton County used when they redirected traffic from going through the bridge to going around it.)

These truss designs are usually repetitive and triangle or diamond shaped. Experts on covered bridges can tell exactly what kind of bridge it is by simply looking at it's truss. If you really want to get fancy, the individual angled boards on the truss are called a strut.

The really unusual bridges have an elongated arch shape, either within the truss or the bridge itself. That's what made the Humpback Bridge renowned and how it got it's nickname the slight curve in it's design meant the center of the bridge was built to be higher than at either end.

The Burr Arch truss bridges are popular in New England, but many in Ohio feature the regular King and Queenpost trusses. These are the common triangle-shaped patterns with one (king) or two (queen) primary conjoining posts.

Throughout the country, there are two dozen types of bridges, many with just a handful nationwide, according to the Federal Highway Administration.

In fact, the FHWA released a very extensive report on bridges from 2005 that's easily accessible online.

Once you're ready to get started, there's a few resources that are best when preparing for a trip to covered bridges. If you're looking locally within southeast Ohio, try contacting the area counties' travel bureaus. They usually have a website or pamphlet dedicated to their bridges.

Venturing outside this region, some of the best places to go are up in Fairfield County near Lancaster and Ashtabula County in northeast Ohio. These counties each have more than a dozen bridges, and Ashtabula County features a covered bridge museum and festival.

Pennsylvania is also well known for their bridges, with more than 200 (it's the only state that has more bridges than Ohio). There are also hundreds of bridges throughout New England, especially in Vermont and New Hampshire.

For more information on covered bridges, consider contacting historical societies, county travel bureaus or doing a cursory online search.

History awaits.