Sketched Feb. 1
Nearly 200,000 people commute on the Highway 520 bridge every day, but in four years of living here I’ve only taken this route a few times. I’m still in awe of the bridge’s engineering and its unique location.
On a clear day this week, the view of Mount Rainier, Mount Baker and the Olympic Mountains from the bridge’s tower was breathtaking. Still, bridge technician Bruce Watkins said it’s easy to get used to it. He’s also used to seeing waves crash over the road and drivers run out of gas.
As a member of the bridge’s maintenance crew, Watkins also gets a view of the bridge from the inside. A boat ride to one of the 4,725-ton floating pontoons helped me understand how the bridge floats and stays straight. The “ah-ha” moment was seeing one of the steel cables that anchor the bridge to the bottom of the lake.
The 47-year old bridge will soon have tolls that will help pay for a replacement slated to open by the end of 2014. The new bridge will not have a tower, but I look forward to sketching the view from its pedestrian lane.
Here are more sketches from my visit:
On this sketch you can see some of the mechanisms that open the bridge. The spans only open for big boats or barges that can’t clear the highrises on the ends, or during storms with sustained winds of more than 50 mph. The last time that happened was in December of 2006. Bridge maintenance technician Paul King referred to the elevated walkway across the traffic lanes as the “guillotine.”
The bridge’s maintenance crew uses this boat to access the 33 pontoons that keep the highway afloat. The entire lenght of the floating section of the bridge is 1.42 miles, which makes it the longest floating bridge in the world.
Bridge technician Paul King invited me to tag along with the crew for a routine check of the pontoons. When water leaks into their hollow chambers it has to be pumped out. Each pontoon is 360 by 60 feet and there are different rooms inside connected by water-tight doors. The depth of the Lake at the center span of the bridge is about 200 feet.
The columns supporting the east side high rise of the bridge rest directly onto the last of 33 pontoons covering the length of the bridge. One of them is pontoon Z, where I followed technician Mark Epstein down a hatch to see one of the anchor cables that helps keep the bridge straight. Their length ranges from 200 to 600 feet.
Coming up on TV:
“Forbidden Access”: Travel Channel tours SR 520 floating bridge
This bridge can tweet:
Anonymous impersonator posts bridge updates on Twitter and Facebook.
Sketch-worthy Seattle. Where should I take my sketchpad next? Do you know of a good sketch story waiting to be drawn? I’d love to learn about it. You can send me your suggestions to firstname.lastname@example.org or via Facebook or Twitter.
February 4, 2011 at 7:06 PM