Any Doctor Who fan can appreciate the Doctor’s many incarnations. Each actor who takes on the role breathes new life into a storied and beloved character. The same can be said for storied and beloved bridges, too.
Take the Brookfield Floating Bridge on Sunset Lake in Vermont for instance. The current bridge is the eighth incarnation of a bridge that goes back 200 years. Carrying a single lane of Vermont 65 across the lake, the bridge is a tourist attraction and is beloved by Brookfield’s 1,300 residents. So you’ll understand why, in 2008, when the seventh bridge was closed permanently to traffic out of safety concerns, there was an outpouring of grief over the loss of the bridge.
But where there have been seven such incarnations in nearly 200 years, the Vermont Agency of Transportation hopes there will only be one in the next 100. That’s because the new bridge (completed in 2015) uses pontoons made from Fiber-Reinforced Polymer or FRP. The previous design had used foam filled timber barrels for floatation. Chosen for its high strength and long life, FRP is also less susceptible to cracking – the bane of any floating bridge.
Designers had a number of challenges to overcome, in particular is the fact that design codes for FRP bridges do not exist. This meant that engineers had to work with researchers, owners and Federal Highways to come up with the design criteria. And at a cost of about $340 a square foot, the result is an economical bridge that suits the bill and will last a very long time.
Check out these articles which offer more in depth background on the Brookfield Floating Bridge and how new and innovative materials were able to breathe new life into an old bridge.
Composite pontoons undergird update of 1820s-vintage floating bridge by Johanna Knapschaefer – September 30, 2015
Vermont replaces it’s floating bridge by Beth Garbitelli and published by the Associated Press – July 4, 2014.Views: 1054