Maintaining Bridges In An Era Of Climate Volatility

On this week’s Talking Michigan Transportation podcast, a discussion about the long-term challenges for transportation infrastructure presented by a volatile climate.

First, Hugh McDiarmid Jr., director of communications at the Michigan Department of Environment, Great Lakes and Energy, joins to talk about the High Water Action Team convened earlier this year by Gov. Gretchen Whitmer.

Wednesday, Gov. Whitmer signed Executive Order 2020-182 and Executive Directive 2020-10 to create the MI Healthy Climate Plan. The governor’s comprehensive plan will protect Michiganders’ public health and the environment and help develop new clean energy jobs by putting Michigan on a path toward becoming fully carbon-neutral by 2050.

"The science is clear, and message urgent: the earth’s climate is now changing faster than at any point in the history of modern civilization, and human activities are largely responsible for this change,” says the executive directive.

McDiarmid explains that Michigan’s water levels are at their highest in more than two decades, causing millions of dollars in damage to private property and public infrastructure, like roads and bridges.

Traffic has been disrupted across the state as flooding and high water flowed over roads and bridges. The problem is particularly acute on the Lake Michigan shore, where roads have been under water in Benton Harbor, Montague, Whitehall, Pentwater, and Elberta in Benzie County. Inland areas have also suffered damage as well as roads near Lake Huron.

Erosion severely damaged the popular Little Traverse Wheelway between Charlevoix and Petoskey and a study indicated restoration could cost millions.

Matt Chynoweth, MDOT’s chief bridge engineer and director of the department’s Bureau of Bridges and Structures, joins the podcast to talk about the perils high water presents for bridge supports, and MDOT’s intensive inspection procedures. 

Chynoweth explains that the issue is not so much the annual precipitation totals but more about the increased frequency of extreme events. Given the median age of bridges in the state, he details how MDOT inspectors monitor bridges and structures around the state during these more frequent and higher intensity flooding events. 

He also explains the concept of bridge scour and why the sustained high water is of particular concern.

Transcript

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Narrator: It's time for Talking Michigan Transportation, a podcast devoted to the conversations with people at the forefront of the ongoing mobility revolution. In the state that put the world on wheels, here's your host, MDOT Communications Director Jeff Cranson.

Jeff Cranson: Hi, welcome again to the podcast. Today I’m going to be talking about climate change and what it means to roads and bridges, not just trying to sustain them, but planning ahead for building in what we know is going to be a more volatile period, and what it means in terms of high water, and the toll that that takes on roads and bridges because this week Governor Whitmer is putting a special spotlight on the environment in Michigan, and what climate change means, and prevention of pollution, and really everything that relates to protecting our precious Great Lakes environment. So, I’m going to start out with Hugh McDiarmid who is my counterpart at the Department of Environment, Great Lakes and Energy, also known as EGLE. He's going to give us kind of a high level view of what's going on with the action team comprised of several agencies that are working on high water issues and Great Lakes levels and the impact that they're having on the environment. Then I’m going to talk with Matt Chynoweth who is the chief bridge engineer and the administrator of the Bureau of Bridges and Structures at MDOT, and he's going to explain what all this means in terms of trying to maintain our bridges. So, we'll start with Hugh.

Hugh McDiarmid: Sure, thanks, Jeff. Thanks for having me.

Jeff Cranson: So, let's go back to the summit in February that you guys convened with several state agencies, but you were obviously in the lead. We know that water levels are some of the highest in more than two decades and that there's really no reason to think that they're going to subside soon. It's taken a toll on certainly transportation infrastructure and state parks and inland waterways as well as the Great Lakes, and, you know, just from a global perspective could you— I mean money is tight, obviously, for everybody, so what do you think you guys can do given the resources and what needs to be done?

Hugh McDiarmid: Sure, Jeff. Let me say at the outset, there's a limit to what we can do because mother nature is pretty much in control of this situation, but we have a certain number of levers that we can pull to help communities, to help homeowners, to help the folks who manage our infrastructure cope with some of these high water levels. That was sort of the focus of the summit earlier this year. So, some things we can do, we do a lot of education. We work we provide technical support and outreach to communities and in helping them know what's coming, how to best deal with some of the threats that the high water has on their communities and on property and potential analyze in shoreline areas. We've also put a lot of effort into expediting our permit process. We give permits out for shoreline work to ensure that it is first of all, going to work, and second of all, not going to harm neighbors because sometimes some of the barriers and things that people put in on an ad hoc basis can actually have negative rather than positive consequences.

Jeff Cranson: Could you cite a specific for that? I mean, not name names but talk about that that kind of thing that somebody, you know, a lakefront property owner might do.

Hugh McDiarmid: Sure, I mean, it's certainly, you know, for a shoreline property owner who is worried about his home being washed away, his vacation home being washed away, or her vocational being washed away, it's certainly tempting to pile rocks, or wood, or hay bales, sometimes sandbags in front of those waves to stop them, and, you know, on the surface that makes sense, but depending on the wave action, the currents, and the places that you are in the lake that can actually have more of a negative effect than a positive effect. It can actually lead to more destruction, not only on your property, but to neighbors who are on either side of you. So, we want to ensure that the things that people are putting in the lake to stop these waves, or to slow down the action of the waves, is not harming the lake, first of all, and not arming adjacent property owners, second of all.

Jeff Cranson: Good, that makes a lot of sense. So, you know, people talk about this in terms of it being cyclical, and that, you know, we certainly know the Great Lakes have risen and declined over the years, but there seems to be something more going on now, so, you know, talk about that a little bit.

Hugh McDiarmid: Yeah, sure, I mean, we're at a period this where a lot of the lakes, a lot of the Great Lakes, were record high water levels, and, as you pointed out, that's the cyclical thing first and foremost. These water levels on the Great Lakes tend to rise and fall in roughly 30 to 35-year patterns, and we're at the peak right now, so, you know, we had I think more than one inch higher than the record levels for Michigan and here on in the month of August, this past August, and, you know, even absent any other factors that would be a problem. It would be a problem for shoreline erosion. It would be a problem for roads washing out, as you've seen on Mackinac Island and various other places, and it would be a problem for homes that are built close to the shoreline or on a bluff that may be eroding, but on top of that cyclical problem that we have when water levels are at their highs, you know, there is the effect of climate change, which is maybe not the key driving force in the water levels but it certainly contributes to it, and by that I mean the water levels are already high we're seeing more frequent and more intense storms, which tend to chip away at the at the bluffs and at the shorelines. We're seeing increases in precipitation throughout the Great Lakes basin. We have recently experienced the highest precipitation in one, three, and five-year periods in recorded history in Michigan and that is increasing lake levels. We're also seeing generally a decline in ice cover each winter, and the ice cover that covers the lakes helps to keep precipitate—or keep the water from evaporating and when there isn’t ice on the lakes you get more water evaporating, which leads to that cyclical cycle. So, there are a lot of factors at play, and while climate change isn't the driving factor it certainly isn't multiplying the effect of the high-water issues.

Jeff Cranson: You know, anything else you want to talk about that, you know, that people might not think of in terms of, you know, the harm to the environment, you know, algae blooms, other problems with fish and plant species, just how disruptive this can be, I guess?

Hugh McDiarmid: Yeah, I can ramble on for a little bit, and, you know, as you know, the governor has taken some bold action this week with the climate change executive order and executive directive, which puts Michigan on the path of carbon neutrality by 2050, which means that we will not be a net contributor of carbon which is the key heat trapping greenhouse gas in the atmosphere. So, that's very exciting and of course, you know, changing the amount of carbon and greenhouse gases we put in the atmosphere is going to take a long time to see effects. The effects that we're going to see in the next couple decades are already in motion. There's not a lot we that we can do about it, so we have to practice adaptation. We have to educate folks and communities to change the way they do infrastructure, to change the way your roads at MDOT are built, to change the way people think about living on the shoreline. Maybe your home should be back farther than you would like it and that beautiful view of the lake might be a little farther back to protect your home, and, you know, communities can do things like preparing infrastructure, ensuring that, you know, if they're in an area that's prone to flooding that they take measures to ensure that their electrical equipment and other sensitive machines are, you know, up above the flood level grade, things like that. So, there are ways that we can prepare for it. The governor's put out put us on a path to reduce our emissions and eventually be in that zero-carbon emitter, but in the short term we're going to have to prepare for some effects, and we're seeing some of those right now.

Jeff Cranson: That's good. That's a good summary, Hugh, and sets us up well since you mentioned roads for our next guest. So, thanks, I appreciate it. As promised, part two today we're going to be speaking with Matt Chynoweth who is the chief bridge engineer at MDOT and is the administrator of the Bureau of Bridges and Structures. He has vast experience with all kinds of bridges, but mainly today I want to talk about high water, and what the ongoing impact is going to be on our bridge structures and their supports, especially, as we know, when water rises currents tend to increase and rapid currents put more pressure on supports. So, thanks, Matt, for taking the time to do this.

Matt Chynoweth: Yeah, thank you very much, Jeff. Thank you for having me.

Jeff Cranson: So, you know, I talked earlier with Hugh McDiarmid at EGLE about the high water action team that the governor convened. They had a summit back in February, several state agencies including MDOT were involved in that and talking about the volatile climate and what it means in terms of protecting waterfront properties and everything from boating and water sports to maintaining roads and bridges. So, in your role as, not just a bridge engineer but really a very intellectually curious person who studies all kinds of things related to infrastructure, what do you think about the rising waters and faster currents, and can you talk about what you've noticed in recent years?

Matt Chynoweth: Yeah, I mean I think the data shows us that while the overall total amount of rainfall in any given year isn't going up or down, the intensity of these storms so they, you know— is much higher than it used to be. So, a storm will come in it'll drop vast amounts of water in a short period of time, and what that means is you've got all these various drainage areas, right, boundaries, and as the water drains from that all eventually gets into the rivers and stream systems that run through the state and then out into the Great Lakes, and, so, you know, what we see is when we have these huge rainfall events water levels rise. We have a population of bridges that we monitor in these events. We have bridges that are considered either scour critical or scour susceptible that we actually have action plans for, and this is not just MDOT. These are all the local bridges too, so, you know, all 13,000 bridges in the state for the ones that are over waterway and the ones that are scour susceptible and scour critical inspectors know to check if there's a USGS gauge station out there that's measuring water levels and flows, we check those. Then we have to do site visits and we check the footings for stability. There's a whole, I guess, behind the scenes resource allocation amongst bridge inspectors that happens when we have these high-water events.

Jeff Cranson: So, explain the concept of scour because I think to a lot of people that sounds like something you do when you clean your sink so—

Matt Chynoweth: Oh, well, yeah, actually it's a very similar action. So, what's scour is there's a couple of different types of scour that we designed for, but basically what scour is as the water flows underneath or through a bridge opening, a lot of times you'll notice that the bridge has abutments that will actually narrow the cross-section of the river right at the bridge, or there are piers that are actually in the water that create an obstruction. What ends up happening is as the water swirls around that number one, the water, the velocity increases, so the water accelerates as it's going through the bridge opening, and that obstruction causes all these different actions. There's different types of water oscillations and vortex shedding and all of this— but what it does is it picks up the material, so the riverbed that is supporting the footing and it erodes it away. What makes scours so dangerous to a bridge is that if enough of the footing is scoured away, if enough of that footing support material is scoured away, you could have a progressive collapse of the bridge, and it's a very difficult thing to inspect for. It's a difficult phenomenon to inspect for because by a visual inspection as the current slows down it deposits sandy, silty materials into the hole that was formed by the higher velocity water. So, by just looking at it you can't tell, so you've got to get in there and you've got a probe. We use sonar to bounce you know beams back and forth to find scour holes, and that's why when these events happen you have to have all hands on deck hands on approach to go out there and do inspections, probe the footings, and take the necessary actions.

Jeff Cranson: So, these are all things that are going on kind of out of sight, and, you know, we know when water's over a road, and, you know, like what's going on up in Alberta and Benzie county right now that a lane of US-31 has been closed all summer because of high water. So, you can see that, you know you're inconvenienced. What you're talking about are things that are going on literally below the surface and that could have a tremendous dramatic effect on a structure.

Matt Chynoweth: Correct, yeah, and, you know, the motoring public may never know all that's happening, all that we're doing after a high-water event to make sure things are safe, but what they do notice is when something gets closed it's an inconvenience, but it's closed because we are unsure of the stability until the water levels kind of recede and we can verify that everything's safe. When we had the dam breach up in Edenville and Midland there, the day after, actually that night, and then the day after, MDOT closed 23 bridges. We had 23 bridges closed by 5 pm the next day. One bridge had completely collapsed, one bridge the approach washed out and then there were a couple of local bridges that had also washed out or were completely underwater, but there were a whole other population of bridges that just driving by, you know, you wouldn't think anything of it. Yeah, the water is flowing under it. It's flowing very fast but they remain closed until we could do a proper scour assessment.

Jeff Cranson: Yeah, we had an event up there last week as you know just to reopen one of those bridges on M-30 in Edenville, and while that only helped out a handful of homeowners because there's another bridge further north that still needs to be reopened, it was a pretty incredible I guess festive event for the families that were happy to have that that connection back. Our crews worked very quickly to do that which is great.

Matt Chynoweth: Yeah, we were fortunate on that one, Jeff, because the one that was reopened last week survived an event that it was not designed for. That much flow coming down in that amount of time, at that speed, you can't design for something like that, but it speaks to the robustness of the design. Yes, the approach is washed out but the bridge itself, the structure, was intact. So, we reconstructed the approaches and reopened the bridge.

Jeff Cranson: So, talk about the median age of bridges in the state, and, you know, how MDOT monitors those bridges and structures during these more frequent and higher intensity flooding events.

Matt Chynoweth: Yeah, so, you know, we have bridges in the state that are still, you know, bridges and culverts that are that have been in service for 100 years, and we have bridges and culverts that have been in service for a year. So, we have a whole vast array of bridge ages and conditions, you know, most of the bridges in the state on the freeway system were built from the late 50s into the mid-70s, but we have this population, you know, this network of bridges that all come from different eras of design. We have many bridges that were designed and built before there was, you know, scour to design against scour and scour countermeasures and stuff like that. We race against time to retrofit those as best we can, but the monitoring that we do is very significant. As I mentioned earlier, you know, each one of these bridges that would be considered scour susceptible or scour critical has a very specific scour monitoring plan, or plan of action, when water levels reach a certain height, and these plans are very in-depth, even going into detail in terms of, you know, who the emergency management contact is if we have to close the bridge, what resources to use, so, I mean, that's how we manage our network. We design bridges now, you know, over waterways to resist scour, so we put the foundation— go ahead.

Jeff Cranson: No, I was just going to say, I mean, since you talk about design and, you know, the transportation planners and engineers they talk about building for resiliency I mean, talk about what that means and how it sounds good you know in theory, but, you know, we all know that Michigan like a lot of states is in a chronic transportation funding crisis and you can't do everything that you'd like to do.

Matt Chynoweth: Yeah, that's a really good point, so these days we designed bridges to resist the 200 year flood events and to be stable in the 500 year flood events. What that means is the foundations have to go very deep. The foundations are very robust, but what it also means is—so there's a cost right there because drilled shaft foundations are very deep, you know, pile driven foundations. That's an expensive venture, but what we also find we're doing is we're lengthening the bridges to get the abutments and the approaches as far away from, you know, the high water, the anticipated, or the calculated high water is possible. So, we're actually finding that an average bridge that's over a waterway right now when MDOT goes in to replace it we are actually increasing the length on average by about 30 percent. So, you take into account the fact that, you know, the average cost of a bridge is anywhere from, you know, 200 to 250 to 300 dollars a square foot. When you're adding 30 to the length of the bridge to get the abutments out of the flood plain or out of the, you know, 200-year high water elevation, again, it just means it's a more expensive bridge than what was originally there and what would have been allowed you know 30 years ago.

Jeff Cranson: So, once again, you know, the Great Lakes and the water are part of what make Michigan a beautiful state and a great place to live, but it also presents tremendous challenges from a transportation standpoint.

Matt Chynoweth: Yeah, absolutely and it's not just Michigan. If you remember years ago hurricane Sandy there that hit the New Jersey, New York coastline, there were areas of, you know, Atlantic city I think and areas of Manhattan that for the first time ever were under water right. These pieces of infrastructure were not built for anything like that. I believe the Holland tunnel was flooded, you know, these are things that just hadn't, you know, don't normally happen that over the past 10 years or so we've seen these events that cause that high water, cause that flooding.

Jeff Cranson: Yeah, no yeah no matter, you know, what we want to argue about the fact is that things are more volatile and as you said, the events are much more extreme and much more dangerous so—

Matt Chynoweth: Yes.

Jeff Cranson: That can't be denied. So, Matt, thanks for taking time to explain this, and I’m sure we'll be talking more about all of these things probably the next time we have a major flooding event and your crews are forced into emergency action on more bridges.

Matt Chynoweth:  Great. Always good to talk to you, Jeff.

Jeff Cranson: Thanks again for listening to this week's edition of Talking Michigan Transportation, and I want to give a special thanks to Cory Petee, who does the sound engineering for the podcast, and to Sarah Martin, of MDOT, who does the show's intro and closing.

Narrator: That's a wrap for this edition of Talking Michigan Transportation. Check out show notes and more on Soundcloud, or by subscribing on Apple podcast.

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