An article in today's Oregonian highlights an ongoing project here in the Rose City: the repairing of the Burnside Bridge. While the endeavor has been ongoing for quite some time, it's now-or-never for the team working to retrofit the bridge. We learn why from the Oregonian:

Worst-case scenario?

The Burnside Bridge falls into the Willamette, tying up river traffic for months, making life miserable for downtown commuters and ending Burnside Street's usefulness as a major evacuation route for downtown Portland.

But those in charge of repairing the ailing bridge aren't about to let that happen. Acknowledging the high stakes, they've engineered a fourfold safety margin into a complex jacking system that will gently lower a 3.8 million-pound concrete counterweight on the east end of the drawbridge.

Did you catch that? 3.8 million pounds, or 1,900 tons, of weight is being prepped to be moved around so they can complete the project. If they fail and if the jack system they're working on somehow malfunctions or breaks, the counterweight could get stuck dangling below the bridge or, perhaps, parts of the bridge could fall into the Willamette. Now that would be a disaster. Again, from the Oregonian:

The counterweight was not designed to ever be moved other than to hold the bridge in position. Jacking it out of position carries with it the risk that the counterweight would slip and need to be lifted, something engineers are not prepared to do.

So, if the weight slips, they (most likely) won't be able to lift it again. Talk about high-stakes maintenance! While the Oregonian and engineers paint worst-case scenarios for analysis purposes, the overall tone is one of confidence as they project the repairs can be completed by the end of the year. Overall, the project cost $9 million but is crucial in light of past bridge collapses, such as the one that recently occurred in Minnesota.

But this leads us to a crucial lesson in modern bridge construction: make it flexible! Once again from the Oregonian:

[Chuck] Maggio [head of Burnside Main Span Rehabilitation Project] said designers of the 81-year-old structure never intended that the counterweight be removed and made no provisions for it.

When the bridge was built, the concrete counterweight was poured in place, into a form that was already attached to the bridge structure.

When we build structures for the future, we can't assume that they'll last forever. Obviously. This isn't to fault the bridge's original construction, because they probably didn't have the physical means to ensure an easy renovation 80 years down the line. But, in this day-and-age with modern technologies, we're in a unique historical position to construct transportation thoroughfares both for present-day benefit and for ease of future repairs. I wish I had an engineer who could tell me how newer bridges are being built today, as I'd love to compare/contrast practices and policies with those of the early 20th century.

What are your thoughts on this project? Or, perhaps, what have your experiences been with the project? Does the doom-and-gloom of the Burnside Bridge into the Willamette worry you, or are you confident that our crack team of engineers will manage to slowly, carefully adjust 3.8 millions pounds of weight that wasn't designed to be adjusted?