I don't know why two centuries old is a concern. If you check out the listing for the Range Line Road Bridge in Wisconsin, http://bridgehunter.com/wi/milwaukee/P40070000000000/ you'll find several photos of bridges in England that were built hundreds of years ago. Here's the Greystone Bridge that was built in 1439 - and is still in everyday use. (The photo was taken by Alan Rosevar who was kind enough to allow us to use it here. Please respect his copyright and don't reproduce it anywhere - thanks!)
If the bridge is one century old, I'm not too concerned, but if it's two centuries old, then that is cause for concern.
Having used this wonderful bridge thousands of times,I can easily say that the original "cornerstone" is marked 1800 and was refurbished in 1900 (another "cornerstone")followed by a possible rebuild in 1964? In the 80's there was talk of replacing this beautiful bridge with a new, straight one. It can be quite dangerous but it is quite beautiful!