CapeCodOnline offered accelerated video and comments about the railroad bridge that spans the Cape Cod Canal. We've enjoyed a few of those 170,056 lowerings and it's worth the trip --
VIDEO: Railroad Bridge throws its weight around
BUZZARDS BAY — We are standing atop the Railroad Bridge and the world looks magnificent. Moments ago, Cape Cod Canal manager Larry Davis gave the go ahead, and the center span began to rise, 2,200 tons, smooth as silk, barely a sound, carrying us more than a hundred feet into the air.
Birds fly below us. The Cape curves away into a salty sunrise. A big wind bends around steel and the American flag snaps to attention. The hectic Bourne Bridge chugs away in the distance. And the canal runs through it all.
The vertical clearance from above mean high water: 135 feet
Time to lower bridge: 2.5 minutes
Length of center span: 544 feet
Source: U.S. Army Corps of Engineers
"There's not a spot on this bridge that I haven't been," says Davis, with obvious affection for the structure and appreciation of how much work it takes to keep it running.
"It's probably the nicest railroad bridge design I've ever seen," he says. "And I've seen quite a few of these vertical lift bridges. But none of them quite have the style, maybe the Art Deco-type of look that this one does."
And what puts the lift in this vertical lift bridge? Two giant counterweights, 1,100 tons each, in the form of steel-plated boxes filled with concrete.
"It sort of works like an old-fashioned window," says Davis. "You have counterweights over a set of pulleys. As the bridge goes down, the counterweights go up, then, as the counterweights go down, the bridge goes up."
Ups and downs are what the Railroad Bridge is all about. As of Friday morning, the bridge had been lowered and raised 170,056 times for train traffic since coming online in 1935, according to statistics provided by Davis' staff.
But what starts the huge counterweights on their up and down exchange with the bridge span? We head into the tower room at the top of the Buzzards Bay side of the bridge and meet the sheaves: four 34-ton wheels, 16 feet in diameter!
The cables that connect the counterweights to the bridge span are guided by the sheaves. An intricate system of gears, powered by a 200-horsepower motor, turn the sheaves, providing enough of a catalyst to get the lift process going, and the counterweights do the heavy lifting.
A twin system of sheaves does the same job in the Cape-side tower. And all that gear-stuff, and the cables and sheaves, are slathered in grease, like mechanical barbecue sauce. Fifteen types of grease are used in the bridge in a never-ending battle against friction.
We head down from the tower in a tiny elevator. Outside again, there's one more chance to see the water of the canal move below our feet, through the grating on the bridge. And another chance to admire the bones of this bridge, built during the heart of the Great Depression and still going strong.
"Some of the stuff that was built in the old days was meant to stick around," says Davis.
2 months ago