Tuesday, September 23, 2008

Pics: Thurman Street Bridge

Thurman St. Bridge

[View Larger Map]
For a bit of variety, we'll tear ourselves away from downtown bridges for a moment and... well, uh, here's a bridge up in the West Hills instead. This is the Thurman St. Bridge, which crosses Macleay Park & Balch Creek.

Sometimes you see the name "Balch Gulch Bridge" used, but you know, it's the West Hills, and the word "gulch" just doesn't fit, somehow. "Gulch" conjures up images of desperadoes with black hats and handlebar moustaches, not sensible Subaru-driving black-lab-owning tofu-eating Portlanders. This post would probably be more interesting if we had desperadoes here, but we don't. Although do have the tale of Danford Balch, the first man to be hanged (ok, legally hanged) in the state. So the creek here is named after a confirmed bad guy, which is quite unusual for Portland. Most of our pioneers (and hence, most names of streets, hills, creeks, etc.) seem to have been your basic boring, starchy, churchgoing, selfless, thrifty, industrious types, who never had an untoward thought or a whiff of scandal about them. Which, I suspect, really means their descendants burned the diaries. But I digress.

Thurman St. Bridge

Besides the usual bridge resources (Structurae, Bridgehunter), the bridge was the subject of a great Portland Tribune story back in 2005: "Creaky old bridge cries out for a fix". Which it very much does.

Thurman St. Bridge

The Thurman St. Bridge presents a historic preservation conundrum. Deep down, everyone realizes it's not a very good bridge: It's old, rickety, and inadequate for present-day traffic; it's not very safe to drive on, especially in winter; it's liable to fall down in the next earthquake; and it isn't even very attractive. Visitors to the park below practically hit their heads on the bottom of the bridge truss, it's so low to the ground, and if they don't, they're liable to get beaned by bolts falling off the bridge. The sidewalks are made of creaky little wood slats, and you can see between them in some spots, and the roadway itself is asphalt over wood, if you can believe that. If you ran across a bridge like this in, say, Peru or Macedonia, you'd come back and tell your friends all about the crappy Third World bridges you encountered. And without photos they might not believe you. Instead, it's right here in Portland. In a fancy part of town, even.

Thurman St. Bridge

Thurman St. Bridge

On the other hand, the bridge was built way back in 1905, which is extremely old by Portland standards, so you can't just scrap the thing. Good or bad, people are used to it being there, and not everyone wants to see it go. In fact, nobody's seriously proposing to remove or replace it, as far as I know. It's also true that there isn't anything else in town quite like it. It's quite the historical artifact, really. It's just that, as part of being so old, the bridge dates back to before the Ford Model T came out (1908, for you trivia buffs). So it wasn't designed for a world in which everyone had a car, much less a hulking multi-ton SUV.

Thurman St. Bridge

Actually, my understanding is that the bridge was designed to carry streetcars. (As in, the rickety little wood streetcars of 1905, not the big Euro-sleek ones Portland has today.) According to the Trib story linked to above, the bridge was built to coincide with the "Lewis and Clark Centennial Exposition", a semi-official World's Fair that was held nearby in what's now industrial NW Portland. It wasn't part of the fair proper; the backers were trying to sell West Hills real estate, and figured a shiny new bridge with a shiny new streetcar was just the ticket to reel in a few interested fairgoers. And you have to admit that'd be an extremely Portland thing to do. (*cough* aerial tram *cough*)

So it's not really a relic of the fair, per se, but since almost nothing survived of the fair itself, it's only natural to want to hang on to anything vaguely connected to the event. One of the few surviving structures, incidentally, is the "NCR Building", which was moved to St. Johns after the fair, and (like many historic buildings in town) is now the McMenamins St. Johns Theater & Pub. Mmmm.... Beeeerrr....

Anyway, PSU has a great site about the fair if you're curious about this long-vanished episode of local history.

Autumn Leaf, Thurman St. Bridge

Walking across is fine, I mean, other than the fact that you're on a creaky 103 year old wooden bridge that's crying out for a fix, over a rather deep canyon, with just a cheap chain link fence for a guardrail. Other than that, no problems here. So after a good renovation, I think the bridge could be great as a pure pedestrian/bike bridge. Although that would involve moving it somewhere else, and building anew here, which would cost money. So that's probably not in the cards in the near future. It's always cheaper, in the short term, to patch things up a little and hope for the best. Hell, that's practically the law of the land here in Oregon. Apply duct tape liberally, throw a blue tarp over the whole mess, and punt it off for the next generation to figure out. Oh, well.

Thurman St. Bridge


David B. said...

I think the critics of this bridge are being overly dramatic.

The one thing it really needs is a healthy dose of routine maintenance and a seismic upgrade.

It has more than a chain-link fence for a guard rail. Yes, there is a chain-link fence (a very sturdy one, with lots of welded steel pipe as a framework to back it up) as a railing on the edge of the pedestrian walkway. But that's not the "guard rail", which is the white steel thing between the walkway and the roadway parts.

So it's a wooden walkway, so what? Yes, you can see between the planks. Big deal. Nobody's going to fall through a gap 1/2" wide. The Hawthorne and Broadway bridges used to have such walkways before they were modernized; I'm glad there's at least one bridge with old-fashioned wooden sidewalks left in the city. I regularly walk across it (it's two blocks from my apartment) and don't feel frightened in the least.

Those old streetcars were not "tiny"; they were quite heavy. Any bridge designed for them is up to the task of carrying trucks and buses, provided it is properly maintained.

Today's bridge engineers use reinforced concrete as their building material of choice, primarily for cost reasons. Unfortunately, concrete (reinforced or not) does poorly in earthquakes. Every time a major earthquake hits a big city, the freeway network (with its many modern, reinforced concrete bridges) always seems to fare very poorly. Every time that happens, the engineers go back to the drawing books, modify their designs for reinforced concrete bridges a little, then pronounced the issues resolved. Until the next earthquake hits and nature again proves otherwise.

The existing Thurman bridge uses structural steel, not reinforced concrete, which has proven to fare much better in earthquakes. Steel, unlike concrete, is not brittle and can flex instead of breaking when subject to unforeseen forces.

In other words, a properly retrofitted Thurman street bridge is likely to be more earthquake resistant than a built-from-scratch brand-new concrete replacement.

BerkeleyMarxSherman said...

Bridge was fully restored in 2014. (Fan of your blog.)