At ‘This Place in History’, we’re in Jeffersonville with Executive Director of the Vermont Historical Society Steve Perkins.
“We’ve talked about a lot of covered bridges, but we’re in a pretty special place here. Very specifically, we’re in Cambridge Junction, in the village of Jeffersonville, in the town of Cambridge,” began Perkins.
“We had a lot of these spaces that grew up because of the railroad. Any time a railroad came through, you often had businesses or roads that were built to serve where that railroad crossed. Sometimes it wasn’t necessarily in the middle of town. You have a lot of places called ‘junction’ throughout Vermont. Think of Cambridge Junction or Essex Junction.”
“So where we are right now is where the railroad came together, but also some roads on one side of the Lamoille River and the other side. A guy named George Holmes decided he needed to connect his business on one side of the river to the railroad, so he built the covered bridge that we’re going to look at today,” said Perkins.
“This is a different kind of construction. We’ve looked at a number of different bridges on this program and many of them have been Town Lattice Truss construction, which was really easy for the layman builder to put together. This type of construction is called the Burr Arch Truss bridge. It was invented and patented by Theodore Burr way back in 1817. He actually developed it in 1807. And it combines the idea of an arch bridge, like a stone arch bridge, with what’s called a King Post truss, which is how early post and beam houses were built,” explained Perkins.
“You can see this structure really easily on the inside of these bridges. All of the bridges built in Cambridge were built in this style. So right behind us here is the arch. Rather than building the arch out of stone, the arch is built out of wood. The arch is in two pieces on either side of this framing. And this framing is called King Post framing. King Post means you have these straight up-and-down posts, which are then supported by beams that come at an angle, creating triangles.”
“Now in the past, they’ve built bridges out of just King Post Truss and they’ve built bridges out of just stone arches. This guy Burr was the one to put them together. His thought was that the arch supported the road and that the truss system supported the bridge over the road. I think there’s a lot of debate with engineers now about which is which, but both of them support you and keep you from falling in the water,” concluded Perkins.
“Fun fact for the day: At 135 feet, this is one of the longest Burr Arch Truss spans in the United States.”
At ‘This Place in History’!
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