Building bridges

After yesterday's post on hate, it seems both wise and healthy to turn my attention in another direction. But honestly, I'm really a bit wiped out this evening.

See, I went up to the big city of Bangor today to help out at another of those amazingly cool Totally Trades days for high school girls. I've had the flubug or something for about two weeks now and still feel pretty crappy, but I figured this thing wouldn't actually require me to work, so I'd be OK. Well, I overslept and had to grab a bite on the way there. Sustained by coffee and a chicken sandwich, I made it there and volunteered to help out with the bridge-building workshop taught by my dear friend and hero, Lib Jamison. I can use her whole name here because she was on TV talking about the program today. That and she's the grand poo-bah (executive director) of Women Unlimited, that amazingly cool non-profit organization I talk about every now and again.

So back to the bridge-building workshop. First, there's a movie. I like that. I don't like movies as a rule, but this one is so incredibly cool. It is a montage of footage taken by old super 8 home movie cameras of the brief, tragic story of November 7, 1940 in Tacoma, Washington, when the beautiful new bridge there broke apart in a gale and fell into the river. The footage is very dramatic and is narrated by Lib, who points out the different bits of oddball stuff on the screen. "See that ball thing right there? That's a piece of concrete rolling around." It was the size of a bowling ball. Holy crap.


Here is a YouTube version of the video. It is narrated by a guy who sounds like an engineering professor. He's not nearly as fun as Lib, but he gets the story right, even if he is achingly dull.

To tell the story in a nutshell: Tacoma Narrows is a windy spot across a fast-moving river and when the engineers drew up the plans for a bridge with 25-foot open trusses, everyone went "ooh" and "ahh" until those same engineers said it would cost $11 Million dollars. In 1938, with the Great Depression still looming large in everyone's memory, the local community howled in protest and demanded a lower price, so a $4 Million bridge was proposed and approved.

Only the new version had huge steel I-beam girders for support and was held up by two large piers and a cable suspension system. There is one remaining example of this kind of design left in America, and it is just a few miles from here where it connects the coastal villages of Stonington and Deer Isle, Maine. It has gizmos mounted over the girders to divert the wind, though. Here is a link to pictures of it. The guy who took the pictures is David Denenberg, and his website has a very cool collection of photographs of suspension bridges of all kinds and styles. Engineering geeks are encouraged to poke around there. Very cool stuff.

So anyway, back in the Narrows of Tacoma, Washington, where the wind comes-a-howlin' through, as wind is wont to do in places called "narrows" those girders acted very much like sails. The wind hit them and caused the bridge to sway. In a most dramatic fashion, I might add.

Now the deck of the bridge (the part you drive on, not the wires and support stuff around it) is made of concrete over which is a layer of asphalt. Concrete bridges require expansion joints so they don't just crack and crumble at the first major temperature change, so there were several expansion joints along the half-mile span of the bridge. Well, when the wind kicked up, it caught in those girders, making everything sway and flex a bit, and with all those joints offering further flexibility, the thing started thrashing around like a giant pool noodle held up by strings. The video is very dramatic. So anyway, the thing crashes into the river and it takes the engineers another 10 years to build a new bridge at that spot. All of the old bits were so bent and twisted and broken that they were useless.

So we get to watch the video, then each team of girls is issued a glue gun, three sticks of glue and a plastic bag with four ounces of Popsicle sticks (approximately 75) and instructions to build a bridge. Or more precisely, build a truss that will withstand pressure when squished from above. I built the squisher used to test them when they're done, but that is another story for another day.

I was astounded at how intense the concentration is for the girls, and how quickly the sticks and glue seem to get used up. There were a couple of burned fingers from the hot glue, but nothing requiring a bandage. In the second session, I sat in with a girl when the class came up short on partners and we had a great time building a truss bridge thingamacallit. Turned out she'd been in a building trades program the year before and was presently taking automotive (mechanics) repair. She understood how support things worked and how to build what we needed. Our bridge withstood 178 pounds of pressure before the STICKS BROKE. The glued connections did not fail - the materials themselves failed. I call that pretty freakin' great for a handful of sticks and some glue. She designed the criss-cross bits and figured out how to hold it all together and I cut up some of the sticks and held the pieces together until the glue cooled.

It wasn't a barn-burner of a day in the traditional sense. No fireworks. No political mayhem. No shouted arguments. Just helping out some friends and meeting some very cool young people. I guess after the past week, with all its culmination of a year of nastiness and contentious debate and name-calling and attacks, a day spent building bridges is probably just what I needed.