Close inspection of the bridge underside reveals stalactites forming on the beams and stalagmites forming on the ground underneath
Photo taken by Calvin Sneed in July 2010
BH Photo #172848
The 1896 Wartburg 15' shows a bridge here so the ferry must have been earlier.
Same deposits as Big Walnut Creek in Indiana.
These photos are very interesting—the white deposits are mostly a sodium carbonate material resulting from a process called alkali-silica reaction (ASR), where the highly alkaline cement binder in the concrete reacts with the high silica content in the aggregates to form a white gel. This gel expands and cracks the concrete over time to form crack patterns in the concrete (photo #12). This process takes many decades to occur, so you normally won’t see this in newer structures. Some of the heavy white stuff running down the side of the pier might be calcium deposits from either the river water or water running down from the roadway, but the white deposits seeping from the cracks in the concrete is likely the sodium from the ASR.
They've done some work in the area. The large mound of dirt is gone, replaced with concrete posts and turned into a hike and bike trail. Additionally, I found some abutments downstream from where the bridge is located. Looks like the bridge listed at this page is the second bridge.
You're right.. this bridge was closed in 1999 when the new Brewster Bridge was built the same year, a half-mile downriver. You can see the new bridge in the distance through the trees to the left in the Street View.
I was shocked to find the calcium carbonate deposits forming stalagmites and stalactites underneath the beams. It is absolutely fascinating. This is the second bridge in East Tennessee where I have found those deposits forming. I thought those were common only in caves, not in the open.
Notice the pier construction. That's how you can tell a bridge built back in the day by the state highway department. The piers are always rounded with notches and groves every few feet.
I think the concrete bridges are just as historic as the steel trusses, but I'm more partial to trusses!
PS Based on Historical Imagery in Google Earth, this bridge was likely open until at least 1998. The new bridge wasn't built until some time between 98 and 07
I find abandoned concrete bridges to actually be as interesting as abandoned through-truss bridges. Thanks for this add, Calvin!