Also to add on to that, I want to mention that this bridge is QUITE high. You might think that the water below it is relatively shallow, but I assure you, Smith Lake is incredibly deep. Duncan Bridge is at least 200 feet above the flooded valley floor below. Here's a photo during the construction of the bridge in 1961 before the Sipsey River backed up behind the dam and created Smith Lake: http://sipseylanding.com/wp-content/uploads/2011/08/Duncan-Bridge-19611.jpg
Go through here all the time, but I guess I never realised until recently how interesting it is, architecturally. A nice contrast to the vast numbers of UCEBs in these parts.
Nice bridge to build across a lake, even back in 1967. Too often when a dam is built for a big lake, any road crossing is a causeway and a UCEB in the middle.