Here are the Answers to Your Covered Bridge Questions
by Kelsey Canfield
Q: Why are covered bridges covered?
A: The roofs were placed on the bridges simply to keep them protected.
With the main support system of the bridges being inside, it is of the greatest importance to keep the beams clear of rain, snow and even sun.
The harshness of Indiana’s climate would leave the bridge rotten from the rain and snow, and weathered from the sun. Not the greatest combination if you need to use this bridge to travel from place to place.
Q: Why does the bridge say “Cross this bridge at a walk”?
A: Early cars had a gear called ‘walk’…..nah. Just kidding! When bridges began to be built, there were no automobiles. Their primary form of transportation was by horse or a horse drawn carriage. Bridges, like many structures, have a natural frequency of vibration. A force that’s applied to an object at the same frequency as the object’s natural frequency will radiate and amplify the vibration of the object. This is called a mechanical resonance. If a horse walks across the structure, they apply a force at the frequency of their step. If their frequency is closely matched to the bridge’s frequency, the horse’s rhythmed step will amplify the vibrational frequency of the bridge. If the mechanical resonance is strong enough, the bridge can vibrate until it collapses from the movement. So, long story short...if you are planning on taking your horse drawn carriage through a covered bridge on a romantic date, take it slow through the bridge - at a walk. As for traveling in your car, take it slow. No need to peel out and blaze through the bridge in fear of the bridge collapsing.
Q: Why are there so many bridges in Parke County?
A: Parke County has a large number of creeks and streams wandering through the landscape. Hence the building of bridges to cross said streams. With an abundance of trees in our area, bridge builders harvested these ancient trees to create the lumber necessary to build these covered bridges. The county was dotted with bridges over every stream and in multiple points of each stream. As the years passed, many still stood. Others were replaced due to flooding, and some were never rebuilt. Then came a time in the early 1900’s that more modern bridges were replacing the older wooded covered bridges. Steel and concrete paved the way to more sound and reliable bridge options.
While others replaced their covered bridges, Parke County continued to just maintain what we had - in part due to the cost of the upgrades. We may have been poor-but we are rich in history!
