Talking Michigan Transportation

Predicting how long a road will last

• Season 7 • Episode 222

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On this week’s edition of the Talking Michigan Transportation podcast, a conversation with a trunkline pavement strategy specialist about how the work in his area helps inform investment decisions. 

Tim Lemon, who works in the Michigan Department of Transportation (MDOT) Bureau of Transportation Planning, talks about how pavement condition is measured and how the data is used.  

He explains that remaining service life (RSL) is MDOT’s primary pavement condition performance measure, which indicates the number of years before the pavement is anticipated to reach poor condition. It reflects the anticipated time in years that a pavement section can continue to provide acceptable levels of service, considering factors such as distress, structural integrity, ride quality, and functionality. 

He also explains that while state trunklines (I, M and US routes) don’t account for the majority of road miles in the state, they carry 53 percent of total traffic and more than 75 percent of commercial traffic in Michigan. 

Jeff Cranson:

Hello, welcome to the Talking Michigan Transportation Podcast. I'm Jeff Cranson. I spoke with Tim Lemon, who is a pavement specialist at the department. He works in the Bureau of Planning and tracks a number of things, doing work that probably most people wouldn't know is even done in the Department of Transportation, which involves figuring out how long pavement is going to last, or at least analyzing data on that pavement to predict the overall health of the system and how much money it's going to take in the future to maintain it. He's really developed quite a bank of knowledge about these things and has a lot of interesting things to say, so I hope you enjoy the conversation. So, Tim Lemon, first time on the Talking Michigan Transportation podcast. I appreciate you taking time to do this. You do, you know, really interesting work, behind-the-scenes work, work that you probably didn't know growing up even went on in the Department of Transportation. I know that, like your job is like so many that I didn't know existed, so thank you.

Tim Lemon:

Yeah, thanks for having me, Jeff. Really excited to be here.

Jeff Cranson:

So talk about first high level. You know what you do and the trajectory that got you into this position.

Tim Lemon:

Oh sure, yeah, so I'm the trunkline payment strategy specialist, which is a bit of a mouthful, but really it just means that I work with our regional payment management engineers to develop our investment strategy for the payment network that MDOT owns. That's where the trunk line part comes in, and so I basically take their investment strategies that they select during our project selection process, I roll that up into an overall strategy for the trunk line network and then use the resulting payment condition information that comes out of that to share with the state legislature, governor's office, et cetera. You know so if you ever see those fun percent, good, fair, poor graphs that get shared all over, that's where those come from.

Jeff Cranson:

Let's get really into the basics. I guess Did you even know the term trunk line before you came to the department.

Tim Lemon:

No, of course not Right. You know, and talking with friends you hear all about that Like, oh, this road outside their house or this one down the street needs construction or is under construction, and you don't really realize it until you work in the industry that different road agencies own different roads, and so MDOT is responsible for just a small part of the transportation network here in Michigan and we're responsible for about 8% of the highways, the trunkline pavements, while the other 92% of that is managed by about 600 different road agencies.

Jeff Cranson:

Yeah, and I came to know the term in my former career as a journalist and came to understand what it was, but I still don't know that any other state uses the term trunk line.

Tim Lemon:

Oh yeah, really I hadn't. I haven't heard it myself from other states, but I guess I wasn't really looking for it. You know, that's just what we call it. Other states it really depends. Some of them own quite a few of their roads you know, almost 90 percent, 80 to 90 percent or so while others, like us in Minnesota, for instance, own, you know, just about 10,000 miles or so, which, compared to hundreds of thousands mile road network, is pretty small in the scope of things.

Jeff Cranson:

Well, and that's something I wanted to get into and that's what confuses people. You're right If you tell people that trunk lines account for 9,700 miles of 123,000 miles of roads, that sounds like not very many, but talk about the traffic volumes on trunk lines versus those local roads not very many, but talk about the traffic volumes on trunk lines versus those local roads.

Tim Lemon:

Yeah, I mean just despite making up 8% of the actual network itself. A majority of traffic in Michigan runs on trunk line routes, 52 or so percent of it. And then if you actually drill down into the freight system, you can see that 75% of the commercial vehicle traffic happens along MDOT-owned trunk line routes.

Jeff Cranson:

Yeah, and that's what obviously businesses depend on more than ever in an age of just-in-time delivery.

Tim Lemon:

Absolutely yeah.

Jeff Cranson:

Yeah, so let's talk a little bit about what you and your colleagues do and how that data is used. You said, obviously, that it helps us inform lawmakers and the governor's office so that they can make decisions and they can look ahead to the pavement forecasts. But I guess, at the most basic level, how do you do what you do? And you're not out there actually analyzing the pavement. You're just taking in the data that comes to you and doing that analysis, right?

Tim Lemon:

It depends. Actually, just two weeks ago I was up in Superior Region with my good friend Allison Amlin, the pavement management engineer up there, and I rode around. I spent over the course of the week 24 hours in the car just looking at roadways. I spent a full eight hours driving around Traverse City and another eight hours in Ishpeming. So certainly try to make it out there to all of our region TSC folks to get a better understanding of their pavement situation.

Tim Lemon:

But, jeff, you're really right that you know I may be helping the regions review their RSLs and talk about the condition, but most of the time I'm a desk jockey, right?

Tim Lemon:

I'm running those analyses in the office as opposed to out on the road or on the construction site. But really the reality of it is what I'm trying to do is help the pavement management engineers understand what rating the roads means. Right? So we use a condition measure called remaining service life. That basically is a forecast of the time until any individual pavement is ready for investment. Right? So that remaining service life how long until we think that some kind of fix is going to be need to be applied to support the public's transportation needs, and so we generally kind of rate them, as if it has two or less years we would consider that to be poor condition, and then if it's seven or less, we would call that fair, and then anything above seven we would call good. So when I say you know, I talk about percent good or fair pavement. That's really a pretty broad range in terms of what that pavement actually needs. It could be ready for investment in three years, or it could be ready for investment in 26 years.

Jeff Cranson:

Well, and that brings us to the idea of asset management and the science involved in that. Just like there's a science involved in what you do, I think that MDOT has been a pioneer, kind of a national leader, in asset management, and maybe that's because of incredible ingenuity and innovation and maybe that's because of necessity If you're starved for funding for that long, you have to figure out ways to make the money go farther. And it's caught hold with several counties and cities across the state who now have asset management plans and use that to inform their decisions too. And I know that's not exactly your area, but you kind of get it. Could you talk about that and why a person's basic instinct would be that worst first is the way to go, and why that's not the way to go?

Tim Lemon:

Yeah, absolutely so. You said whether or not it's necessity or it's ingenuity, it will. You know, necessity is the mother of invention. Right, we have had to stretch our dollar as much as we can to try and provide the best transportation surface that we can for the public, and a big part of doing so is preserving our pavements, not just rehabilitating or replacing them. So, as you mentioned, you kind of alluded to that worst first approach would be to just go out when a pavement is ready for investment, go through and reconstruct or rehabilitate it. But we have, at MDOT, applied a more preservation-focused approach where we're looking at okay, after we construct something, when is the next time we're going to come back and do a surface seal or a functional enhancement that's going to protect that investment that we just made at a cheaper rate?

Tim Lemon:

Basically, those preservation fixes, I measure everything in lane miles. That's just the way that my brain works now after doing this for so long. But you know I measure the cost per lane mile for the preservation fixes. It tends to be in the hundreds of thousands of dollar range. You know, 300,000 a lane mile. Basically, we take some kind of asphalt or sealant mixture and spray it over the top to prevent the underlying asphalt or concrete service from oxidizing and cracking. It provides a wearing course for the traffic to cause damage to over time. That is really a pretty cheap and effective way to maintain the system, as opposed to reconstructing, which, the cost of which we're seeing escalate not just, you know, over the last 10 years, but over the last three to four years, to record amounts. You know, I think last I checked, the cost to reconstruct asphalt pavement tended to be around three to four million dollars a lane mile.

Jeff Cranson:

So when you're talking about…. Sorry to interrupt, but there's a difference between an urban lane mile and a rural lane mile too, right?

Tim Lemon:

No doubt, yeah, absolutely. And that all comes down to the you know, the curb and gutter, the sidewalk, all that stuff you have to get into. And so when I'm talking about averages, I do mean statewide right, and typically somebody, like some of the engineers in metro region, are going to have to focus on concrete investment itself. So concrete reconstruction tends to cost more than an asphalt in general because of some of those ancillary concerns. But when we're talking about preservation versus rehabilitation or reconstruction, we're talking about an order of magnitude more money, and so that's really what I want people to think about when we come back and revisit a road after it's been recently reconstructed is all we're doing is trying to protect that investment over the long term using a cost-effective approach.

Jeff Cranson:

Yeah, that's very well explained. I think what also people need to be reminded of is that and you know this anyway, but going on the routes you just did, which is really interesting, I didn't know you were out there doing your own observation oh yeah, that almost every city, village, even the unincorporated communities, and it's M-43, it's I mean, it's everywhere there's a trunk line that is a main street and is really important to that community, but it's still owned and maintained by the state. So talk about how, when you drive on these roads, you start to get a feel from, I guess, visually, and maybe from the ride, about that condition. You can probably get to the point where you can predict it, even without the people that actually do that coming to you and saying this is fair or this is good or this is poor. Right.

Tim Lemon:

Oh, absolutely. Yeah, I mean just looking at. I mean we'll roll down in the van, we all pile up into an eight or nine passenger van to review these roads and so as we're going down them, people will just shout out a number and we generally can find consensus pretty quickly in the van regarding the condition or at least the amount of time left before we think that something needs to be done. Something needs to be done. But I have some serious concerns about, just like you said, jeff, how many downtown areas, small communities, are struggling with poor trunkline pavement.

Tim Lemon:

The Rebuilding Michigan Bonding Program really helped us out by investing a bunch of money into the freeway condition via a bond financing program.

Tim Lemon:

That obviously has to be paid back.

Tim Lemon:

But what it did do is help us make improvements to that freeway system now as opposed to having to do it later after additional inflation has set in and additional deterioration has set in right.

Tim Lemon:

So it gives us that time value of money opportunity there. But what it didn't do, unfortunately, was address some of those key downtown small town trunk lines that are folks' main streets to go, drive, to work and back every day down this road and so just going through some of those more rural areas in northern Michigan, I really got to see just what a difference a good you know down Main Street makes to a community right. It makes the neighborhood feel different, it makes the community planning feel a little bit more intentional right, because the road is in good shape. And so I just I want to express that a majority of our non-freeway trunk line now is in fair condition, which means that it has five years or less before it's considered poor, before our engineers think that, hey, this is going to need some kind of a fix. So I mean, we're talking about a lot, a lot of small towns. You know local areas that are going to need a lot of work here in the next few years.

Jeff Cranson:

Stay with us. We'll have more on the other side of this important message.

MDOT Message:

Even with the best planning, backups and traffic congestion can occur during road construction. This can pose hazardous situations for both motorists and construction workers, particularly when drivers are distracted. Motorists are more likely than workers to be killed or injured in work zone-related incidents. Additionally, the leading causes of all work zone related crashes are distracted driving and speeding. So it's crucial to do your part in ensuring the safety of both drivers and focusing on your most important task safe driving. Slow down and stay focused.

Jeff Cranson:

As you do that driving. There's a lot of misunderstanding that's come forth lately in discussions among lawmakers and some reporting out there that doesn't fully understand how the pavement is evaluated, and it isn't just as simple as a windshield survey, although, from what you're saying, that by itself can be an important contributor to making these decisions. So can you talk about that?

Tim Lemon:

Oh, absolutely yeah. So I mean it's not as simple as a windshield survey. You know I contrast our remaining service life measure to the local agencies, the Transportation Asset Management Council, who uses the Pavement Evaluation Service and Rating PASER, if I got my acronym right. That rating is truly a windshield survey. That you know. I don't have anything against it. I think that it works well.

Tim Lemon:

It's just not what we happen to use at MDOT, because our STC goal is in terms of our remaining service life measure, and our remaining service life measure is directly integrated into our asset management process, right? How long before we need to do something to address this particular stretch of pavement, right? So it's a really good communication planning tool in that way, but it's really not just a windshield survey. We go out there, obviously, and raid the roads and talk about what sort of fix this is going to need, but it's not just what you can see with your eyes that makes that decision right. It's what's happening underneath the surface, based upon, you know, cores that the engineers are taking, the history of the pavement, the different types of distresses that we're seeing, you know, above and below the pavement surface. So all of those things, including drainage and traffic, get factored in by the engineers when they're creating those remaining service life estimates.

Jeff Cranson:

So, along with the misunderstandings about that also, there's a lot of discussion right now about Act 51, which is the public act, the law in Michigan that decides how the funds are dispersed between the counties, the cities and the state routes, and very roughly, 39% goes to state routes, 39% goes to county roads, 22% goes to cities and villages, and there's a lot of talk about how we need to look at that again and I always equate that to you know, pulling the thread of a sweater, and that when you do that, the whole thing's going to unravel. It sounds really good, but I liken it to Churchill's comment about, you know, democracy, it's the worst, except for all the rest. And I think that's how I feel about Act 51. Everybody thinks this is something we have to fix, and then they start looking into it and find out yeah, you know what I can see why we did it this way and how this all holds together. So talk about your own theory you've developed on that all holds together.

Tim Lemon:

So talk about your own theory you've developed on that. Yeah, I don't have anything against Act 51, I think, and I certainly don't have anything against maybe reviewing and reconsidering some of the decisions that are made by Act 51. That being said, act 51 does get reviewed and updated fairly regularly. Don't make me pull out my Google machine here but it's not something that's completely stagnant, right, it dates to 1951, that it's ultimately a political device, right, that distributes that revenue across those 600 or so agencies that I mentioned earlier. And, like I said, I think reviewing it, reinterpreting it, understanding and transportation needs is all worthwhile.

Tim Lemon:

It's just, I don't think it's any sort of a silver bullet when it comes to solving the problem that is Michigan's pavement condition performance gap. Right, you can spread the money however you like, but it's not going to overcome a $2.5 billion investment gap. And then that $2.5 billion that I cited, that's just trunk line need. That doesn't even include the locals. I'm not, I'm really not meant to be talking about local investment need and, in particular, they don't have a goal really based on pacer. But you know, in order to meet our state of good repair goal, it's two and a half billion dollars annually that we'll need to be able to do that and, you know, reworking Act 51 really just is not going to get us there.

Jeff Cranson:

It's interesting that you say that too, because you've been in this job for a while and you know you talk to family and friends, obviously, about what you do. And what do you say when they say look how much I pay to register my car and look how much I pay for gas. I don't understand why the roads can't be in better shape without getting you know too deep. How do you explain that to them in a few sentences?

Tim Lemon:

It's just like how much you're paying at the grocery store. Ultimately, right, I just had a conversation with this about one of my fellow planners that inflation rate has hit everything, not just that your eggs at the grocery store, but the price of asphalt, the price of concrete and all the sub base and all that stuff that we pour into that roadway. All those materials cost a considerable amount of money and the inflation on those has gone up, you know, above and beyond your typical indexes for inflation. So really what I tell them is that, yeah, I mean the cost of everything has gone up and we, our revenue, our state revenue, meant for the maintenance of trunk line routes, really has not kept pace with that.

Jeff Cranson:

Well, and that also that inflation has affected the cost of labor and the equipment that the contractors have to buy too. Yeah absolutely so. What else would you want to get across to people about you and your unit and why you guys do what you do? And while it's out of the public light, it's really important. What would you want to say?

Tim Lemon:

Sure, I just want to speak to the hard work and dedication that I know that every MDOT pavement management engineer applies, to the hard work and dedication that I know that every MDOT pavement management engineer applies to their everyday work. They try very hard to squeeze every last dollar they can out of state funds to improve the condition of their networks. We meet monthly to discuss best practices and new technologies that are coming out that we can use to. You know, leverage, you know new approaches to pavement management and stretch the dollar even further than we already do. So it's not a matter of the will of MDOT to be able to take these important state funds and apply them appropriately to their network. It's a matter of the availability of those funds to meet the existing need, and we simply do not have enough yeah, well said well, tim, thank you.

Jeff Cranson:

I appreciate you uh taking time to do this. I'm sure that uh I'll have you back because I uh enjoy talking about these things too and you break it down, I think, really well for the layman.

Tim Lemon:

So thanks again yeah, I appreciate it, jeff, and I'm happy to come back anytime.

Jeff Cranson:

I'd like to thank you once more for tuning in to Talking Michigan Transportation. You can find show notes and more on Apple Podcasts or Buzzsprout. I also want to acknowledge the talented people who help make this a reality each week, starting with Randy Debler, who skillfully edits the audio, Jesse Ball, who proofs the content, Courtney Bates, who posts the podcast to various platforms, and Jackie Salinas, who transcribes the audio to make it accessible to all.