May 3, 2013 at 6:36 PM
South Park Bridge gets guts of steel
Sketched May 1, 2013
The giant pieces of steel were lifted and lowered so fast by the barge crane, I doubt many in South Park saw what happened here Wednesday.
Two years after construction of a new drawbridge over the Duwamish River started, workers are beginning to install the guts of the bridge — the actual steel mechanisms that will make the spans go up and down.
“Today is a milestone,” said project engineer Tim Lane, who joined me by the river bank and borrowed one of my sketchbooks to diagram how the “teeter-totter” will come together.
“You have to have the fat kid on one side,” he said, referring to the counterweight that will be held in place by these three3-story steel towers shown in my sketch.
Lane said the bridge is about two-thirds done and on schedule to open next spring. He expects the first draw span to be bolted to these pieces sometime in July.
The excitement of the engineering team was shared by Via Vadi cafe owner Maria Porco, one of the nearby business owners I met in 2010 when the old bridge closed permanently for safety reasons. “You know things are going to get better,” she said. “It’s starting to look like a bridge.”
— ooo —
Lane downplayed his sketching skills, but he quickly scribbled some great diagrams. The two “trunnion towers” installed Wednesday will be connected with more prefabricated steel beams and the whole structure will hold the south span of the bridge. The little circle in the side view is the trunnion, the pivoting point for the bridge’s span. Next to it you can see the counterweight, a big rectangle marked with an “x.”
After the towers were installed, I put on a hard hat and reflective vest and stepped down a 20-foot wooden ladder to access the space inside the pier, which is about the size of a basketball court. Lane and fellow engineer Jill Marilley gave me a crash course on the history of Seattle drawbridges, pointing out that most of them were built in the late 1910s and early 1920s following the construction of the Lake Washington Ship Canal. The original South Park bridge was built in 1931.
As we chatted, a worker drove the Genie cherry picker out of the way and the barge crane dropped a big container loaded with tools. Marilley commented what a special project this is for Seattle and for South Park. “Moveable bridges don’t get built very often,” she said.
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