MICHELE NORRIS, Host:
Nationally, more than 73,000 bridges are rated structurally deficient by the Federal Highway Administration. Another 80,000 are rated functionally obsolete. After Wednesday's bridge collapse, officials across the nation are wondering what they should do to shore up aging bridges in their region.
Mark Leonard is a state bridge engineer at the Colorado Department of Transportation. More than 100 bridges in his state are in poor condition.
MARK LEONARD: The bridges in poor condition are the ones that have outlived their useful remaining economic-service life...
NORRIS: And that means?
LEONARD: ...their space. By the work we do, the repairs that are needed, we keep them safe. But the cost of the attention needed to keep them safe has reached the point where it would make more sense to replace the bridges.
NORRIS: So it's almost like the money that you put into your car. At some point, it's just better to replace it?
LEONARD: That's a great example. The car you're driving every day, you could keep it running forever if you spent enough money on repairs. But it reaches the point where it makes more sense to buy a new car.
NORRIS: But based on what you saw in Minneapolis, are you going to fast track any of those repairs on the bridges that are said to be in poor condition, or possibly close some of them so you can do closer inspections?
LEONARD: Well, the fast tracking of major rehabilitation or replacement is a budgeting decision. It's a financial decision, not an engineering one. The decisions to make repairs is a engineering decision. And that we are already aggressive with. You can't let money get in the way of safety. And so when we recognize that there is a repair, it's taken care of.
NORRIS: Mr. Leonard, tell us - like, I'm hearing you say two things. You can't let money get in the way of safety. And yet, some of the repairs that might be needed, you're saying that you don't necessarily have the funding immediately to make them.
LEONARD: Mm-hmm. And the repairs are necessary for the safety, whereas the money that's needed for replacement or major rehabilitation, that is more for, to optimize things economically. With time, as a bridge gets older in a worsening condition, you end up putting too much money in the repairs. And so to replace a bridge, which is much more expensive, harder to find the money in the short-term, in the long-term, it would make more sense.
NORRIS: I want to ask you about one bridge out there in Colorado, in particular, the South Platte River bridge on I-25. And I understand that there are more than 200,000 cars on that bridge every day. And I also understand that is said to be in poor condition. What's wrong with that bridge? What's the problem there?
LEONARD: We're having quite a bit of corrosion due to rusting of the structural steel members that make up the bridge and hold it up. It's a steel arch bridge. And being structural steel, it is, of course, it rusts when the water and the salt gets to it. So we have to go in and rebuild those structure members. You can think of it as patching them.
NORRIS: You know, when I think of a massive bridge and all these cars going over it, when you talk about that kind of corrosion in a huge steel structure, can you really fix that as you go?
LEONARD: Yes, you can. And it does get complicated at times. And like that bridge in Minneapolis or the one we're talking about here in Denver, they are bigger, more complicated structures. And it's an expensive thing to do. It's not that you can't do it, you have to do it.
NORRIS: Where is the bridge over the South Platte River?
LEONARD: It is very near central downtown Denver. In fact, from this bridge, you can see downtown Denver.
NORRIS: Do you happen to cross that bridge on a daily basis?
LEONARD: Twice a day.
NORRIS: I don't want to put myself in the passenger's seat of your car. When you are going across that bridge this morning, what was your frame of mind?
LEONARD: Well, this particular morning, I didn't think about it. But on most mornings, when I go over the expansion devices - what the expansion devices are, it's joints in the bridge deck that lead to water leaking through to the bridge below. And because they are old and in poor condition, you get a bump every time you go over it. And that bumpy ride reminds me that instead of fixing what's below those joints, it'll be better to rebuild the bridge and get rid of them, which would cure the problem.
NORRIS: Mr. Leonard, thank you very much for speaking to us. All the best to you.
LEONARD: You're welcome.
NORRIS: That was Mark Leonard, the state bridge engineer at the Colorado Department of Transportation.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.