Natural Bridge in Virginia

Last week on vacation I took a road trip down to Kentucky and Tennessee. On the way back I stopped at the Natural Bridge in Virginia.

The natural arch spans 90 feet across Cedar Creek and is up to 215 feet over the creek floor and consists of a limestone strata. The bridge carries US highway 11 and when cross the bridge has fencing so you can't see the view from the top (believe me I tried).

When I was at the natural bridge my first thoughts were on how they inspect a land bridge and what type on monitoring they is performed on it. I thought it would be a simple google search but so far I haven't found any information on it.