Josh Dietsche on Structural Integrity of Wisconsin Bridges

Frederica Freyberg:
How aged are other bridge crossings in Wisconsin? According to the National Bridge Inventory, of the more than 14,000 bridges in this state, nearly a thousand are classified as what they call “structurally deficient.” We turn to Wisconsin DOT Bureau of Structures Director Josh Dietsche for more. And thanks very much for being here.

Josh Dietsche:
Sure, not a problem. Happy to join.

Frederica Freyberg:
So what does it mean for a bridge to be “structurally deficient?”

Josh Dietsche:
So it’s a term that probably sounds a little scarier than it is. Really it just means that there is something, some kind of deterioration that’s been noted with the bridge. We always try to stress that that doesn’t mean it’s unsafe. If there’s a bridge open in the state, open to travel on, you can feel safe traveling across it.

Frederica Freyberg:
So does Wisconsin have a lot of older bridges, like the one like the Lansing Bridge?

Josh Dietsche:
Not many that are quite as old as the Lansing Bridge. The average age of the bridges that the state owns is about 37 years. The average age in the local system is about 42 years old. So yeah, something as old as the Lansing is a little bit atypical.

Frederica Freyberg:
In Wisconsin, what specific bridges need immediate repair or removal? Are there any?

Josh Dietsche:
Again, I would stress that if it’s open, it’s safe. So we always have a program where we’re going in and rehabilitating or replacing bridges. So you mentioned that there’s over 14,000 bridges in the state. About 2% of those are classified as being in poor condition. Kind of at a high level, we – as we inspect bridges, they get rated as either good, fair or poor. And so again, with about 2% of those bridges in poor condition, those are the ones that we’re focusing on. Again, not because they’re unsafe, not because you shouldn’t be traveling over them, but just because they’re going to need some work to keep them in service in the near future. So those are the ones that we’ve got in the program that are in the planning stages for, you know, again, getting some kind of rehabilitation or potentially being replaced.

Frederica Freyberg:
How heavy of a lift is it to inspect all of these more than 14,000 bridges across the state of Wisconsin?

Josh Dietsche:
Yeah, I think most people are surprised when we talk about it that we do have that many bridges in the state. You know about the big ones that you travel over but there’s so many that are over just small creeks or small rivers that you probably don’t even realize when you’re going over a bridge. So yeah, of those 14,000, about 5,000, a little over 5,000 are owned by the state, and the remainder then are owned by local municipalities, cities, villages, towns, and so on and so forth. So the state bridges are inspected by mostly by state forces, although we do use consultant engineers as well. And the same thing on the local side, the local side, they do have some local staff that will inspect bridges, but they lean heavily on consultant engineers as well. So when the bridges are in good condition, basically new, they can be inspected on as much as a four-year cycle. But for the most part, bridges are required to be inspected on a two-year cycle or as they get in that worst condition, into poor condition on an annual basis. So yeah, it’s a heavy lift depending on the size of the bridge. The larger bridges may take up to a week to inspect some of the larger bridges, like you referenced the Lansing Bridge or some of our more signature bridges. Others, you know, it can be done in a morning or an afternoon. But yes, it’s definitely a pretty big effort.

Frederica Freyberg:
We took a look at the work that’s happening on that bridge from De Soto to Lansing, and it made me wonder, how tricky is it to repair bridges while they’re still in use?

Josh Dietsche:
Yeah, it depends on the situation. You know, obviously the traffic is a big thing that plays into — that plays into that. You know, if you’re trying to repair a bridge on the interstate, there’s going to be lane closures. There’s a, there’s a large bridge over the Wisconsin River just north of Portage that’s being replaced right now. If you’ve driven through that area and in that case, you’ll see lane closures or lane shifts. So it’s definitely possible. But yeah, it does present some complications for sure. But again, we make — we make sure to do it in a way that is safe for sure. And as — we try to minimize the disruption to the traveling public as much as we can.

Frederica Freyberg:
All right. Well, we are all glad to know that the bridges are safe. John Dietsche, thank you so much.

Josh Dietsche:
No problem.