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The floating bridge

I’m an infrastructure geek, intrigued by the planning and architecture and design that lets millions of people live and get around in a geographically small urban area. If you don’t share that enthusiasm, please forgive the next eight paragraphs.

Evergreen Point Floating Bridge
across Lake Washington


The city of Seattle is built on an isthmus, with the Pacific Ocean to the west, and Lake Washington, 20 miles long and two miles wide, to the east. Swanky suburbs are on the other side of the lake, and several bridges cross the water. Because of the lake’s setting, depth, and its soft bottom, suspension bridges are impractical here. Instead, the lake’s bridges are of an unusual design — they float.

The bridges are built on concrete squares, called pontoons. The pontoons are hollow, so the concrete floats, and supports the entire weight of the highway and the traffic.

Today’s story takes place on the Evergreen Point Floating Bridge, or as it’s more formally known, Governor Albert D. Rosellini Bridge. Fun fact: It’s the longest floating bridge in the world. Another fun fact: The second-longest floating bridge in the world is nearby, on the same lake.

Maybe you’re wondering how boats get past a floating bridge? Water traffic on Lake Washington is almost entirely pleasure boating, and smaller craft can cross under the bridge’s approaches, at either shore. There’s not enough clearance, though, for big sailboats and other taller vessels, so schooners and yachts queue near the drawspan, in the middle of the lake.

Opening the drawspan is a complicated process that halts traffic for half an hour, so there are no bridge openings during rush hour Monday-Friday. When it’s needed, though, lights flash, bells sound, guardrails come down, and cars and trucks and buses stop, much like at a railroad crossing.

One section of the bridge, about 100 feet long, is designed to hydraulically hoist itself up and out of the water. Once it’s standing at about a man’s height, that section slides backward, on top of the adjacent section of the bridge. This leaves clear sailing below, allowing boats to pass, usually accompanied by a chorus of flipped fingers and foul language from people in vehicles backed up in both directions.

When the water traffic has sailed away, the raised section of the highway slides back over the water, and is gently lowered to sea level. Employees wearing vests and walkie-talkies doublecheck, making sure everything has clicked as it’s supposed to, and that the pavement is perfectly aligned. Then the guardrails are removed, and highway traffic resumes.

The bridges and the drawspan are quite impressive, but like everything else in modern life, once you’re accustomed to it you take it for granted. So what happened on December 22, 1989 came as quite a surprise.

The drawspan section,
with the deck raised about halfway

Nobody knew except the workers, but every Friday morning the bridge’s drawspan mechanism was tested — while traffic rolled across the bridge. First and always, the power settings were dialed back, so there wouldn’t be enough juice to operate any of the machinery. Only a few volts would be sent along the command wires, just enough impulse power to be measured, and show that the system was functional. In hindsight, this may have been less than the best possible protocol.

Investigators established that the bridge crew did nothing wrong. The power was at its minimum level, and nothing should’ve happened. But something happened. Without guardrails in place, with lights not flashing and bells not sounding, 100 feet of the freeway rose out of the water.

Quoting from coverage in the New York Times:

The drawspan lifted about four and a half feet, creating a wall that three vehicles drove into head-on. Several cars were left perched on the elevated section of the bridge, some with blown tires and mangled metal from hitting the rising span. None of the cars went into the water.

It’s a freeway, speed limit 55, so it’s surprising that only one person was killed — Raili Korkka, a 44-year-old Seattle woman. Her family must’ve hired a remarkably incompetent lawyer, as their lawsuit was settled three years later, with the state paying just $100,000. In a separate lawsuit, the state paid $1.9-million to someone who’d survived, but hired a better attorney.

I lived in Seattle in 1989, and drove that bridge frequently. I'd driven across it the day before. When it’s local and peripherally personal, you don’t forget, so the end of that lady's story pops into my mind now and again.

She never knew what happened. She was just driving along, when the highway in front of her became a wall. It was nobody's fault, just a crazy confluence of ordinary events, with a wild card dealt in. And you know, there is always a wild card.

 8/26/2021

itsdougholland.com 

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6 comments:

  1. "Be careful out there."

    ReplyDelete
    Replies
    1. It's beyond that, though. Something like this, no amount of "careful" can protect you.

      Delete
  2. This is not the kind of post I expect on this blog. You do that a lot. I mean that as a complement. You are a good writer.

    ReplyDelete

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