Travel behavior, or the how, why, and when we travel, has a great impact on our community and our lives. Pat Mokhtarian discusses how these travel decisions are changing through emerging technologies.

Emerging technologies are reshaping how we work and how we get around, from teleworking to rideshares to autonomous vehicles. Pat Mokhtarian discusses what considerations and expectations inform our travel decisions.

Mokhtarian is a Susan G. and Christopher D. Pappas Professor & Group Coordinator in the School of Civil and Environmental Engineering at Georgia Tech.

Album art, illustration

Steve W. McLaughlin

Georgia Institute of Technology
Provost, Georgia Institute of Technology
Professor, Electrical and Computer Engineering
Steve McLaughlin, headshot

Patricia Mokhtarian

School of Civil and Environmental Engineering
Susan G and Christopher D Pappas Professorship
Pat Mokhtarian, headshot


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[steam whistle]

Steve McLaughlin: You're listening to the Uncommon Engineer. I'm your host, Steve McLaughlin, dean of the college.

Radio Announcer: We’re just absolutely pleased as punch to have you with us. Please say a few words.

Steve McLaughlin: Hi everyone and welcome to the Uncommon Engineer podcast. I'm Steve McLaughlin, dean of the Georgia Tech College of Engineering. Our podcast is all about how Georgia Tech engineers make a difference in our world, in our daily lives, and in ways that you may not expect to see from an engineer. In this episode, we'll be talking about travel behavior. How, why, and when we travel has a great impact on our community and our lives. Emerging technologies are reshaping how we work and how we get around, from teleworking to ride shares to autonomous vehicles. Our guest today is Dr. Pat Mokhtarian, professor in the School of Civil and Environmental Engineering here at Georgia Tech. She'll explain what we know about our travel decisions, how we're working to understand these incredible changes, and what that means for society. Welcome to the program, Pat.

Pat Mokhtarian: Thank you very much.

Steve McLaughlin: Pat, what's on my mind right now is ride sharing, you know, things like Uber and Lyft, and how autonomy, you know, self-driving cars, might affect those transportation options. It's incredibly fascinating. Can you start by saying a little bit about your research interests and how it overlaps with those?

Pat Mokhtarian: My research interests are right front and center with those topics, and it's really on a lot of researchers’ minds these days. I tell my students there's never been a more exciting time to be in travel behavior research. The first 20 years of my career or so it was pretty much business as usual as far as transportation technology was concerned. Now information technology was changing rapidly, which was one of the attractions to me of studying telecommuting and other applications, but transportation itself was pretty much same-old same-old for decades on end. But now with the convergence of information technology and transportation technology, we're seeing this explosion of new transportation services such as ride hailing and of course automated vehicles just over the horizon.

Steve McLaughlin: Atlanta, with Georgia Tech at its center, does have some real transportation problems. Can you say a little bit about your work with millennials and how they're thinking about transportation?

Pat Mokhtarian: Yes. Millennials are really interesting because, of course, there are a lot of stereotypes being bandied about regarding millennials and their attitudes are changing. They’re more environmental. They're more diverse. They’re more urban-oriented. And that's certainly true of a segment. But one thing we've discovered is that a lot of studies of millennials have been based on convenience samples in college towns or major metropolitan areas. And so one of the things we wanted to do in our research was get a more representative cross-section of millennials throughout, for example, the state of Georgia—one of my projects—and see how uniform, if you will, the stereotype is being achieved.

And one of the things that's emerging is, guess what, there's a lot of diversity among millennials. And even as Millennials age then of course they're starting to show behavior patterns that are pretty similar to the generation above them. But what we're also seeing is a gradual shift, so rather than this kind of binary switch that turns on when you're a millennial and turns off when you are the older generation, there does seem to be gradual changes in attitudes that are a function of age. And so I think even as millennials get married, have children, to some extent buy cars, move to the suburbs, they will still be different in meaningful ways from the generations before them in that, for example, they may demand more walkable, bikeable suburbs. They may shed one vehicle—instead of being a two-car household, they may be a one car household and use ride-sharing and car-sharing to make up the difference. They are more transit oriented. They are more pro-environmental as a whole with, again, exceptions. You talk to a rural millennial in Georgia, they may be pretty typical of what a 19-year-old twenty years ago was like.

Steve McLaughlin: Well, you know, how are car manufacturers modifying the market and their products to address this? Or has there already been a significant impact on the market?

Pat Mokhtarian: I've heard at least one car manufacturer type say, “You know, we lost the younger generation when we made cars so hard to fix that the teenagers could no longer do it with their dad in the garage on the weekend.” So I think that this generation has kind of lost the tactile and the emotional connection to automobiles that was more the case in the past. And automobile manufacturers are certainly moving with the times, so I would say all the major manufacturers now are seeing themselves more in the mobility business than in the car manufacturing business. So many of them are in joint ventures or buying, you know, ride hailing operations of various kinds, certainly of course exploring the automated vehicle market extensively.

Steve McLaughlin: Can you talk a little bit about public transportation versus ride sharing and what's going on there? Where is that all headed?

Pat Mokhtarian: Yes, it's a conundrum of sorts because ride sharing can support public transportation, and that's obviously the hope that it can solve the “last mile problem” as we call it—you know, getting someone from home to the transit station and from the station to the destination. On the other hand, it can clearly compete with public transit. And I'm not aware of specific studies done in Atlanta, but studies done elsewhere have found pretty strong evidence of the competition effect where transit ridership may be falling that in a way that's being attributed at least in part to ride hailing services.

Now of course there's been other factors, including the economy picking up so people can afford their own cars, and that's also contributing to the drop in transit ridership. But whereas in the past 10 to 15 years, transit ridership had been ticking upward for the first time in quite a while, now it's kind of falling back down again. So there's definitely an interplay, and I think the challenge in some respects for the transit companies is also to see themselves in the mobility business, not in the rail business or the bus business, but how can we work together with a variety of elements of the transportation package to make the experience more seamless for the passenger.

Steve McLaughlin: How does a, you know, General Motors, Chrysler, Honda—how do they become more of a mobility company instead of a car manufacturer? How does that manifest itself in the company's products?

Pat Mokhtarian: Well, one thing that's being talked about a lot is mobility as a service, the concept, M.A.A.S.—it's already got its own acronym—and the idea is that instead of owning a car you subscribe to a mobility package if you will. And for a certain number of dollars a month, you may get unlimited rides or a certain number of rides or a certain number of miles. And within that package, you can use any mix of modes that is most convenient. Obviously that goes beyond just automobiles. It requires coordination among auto companies and transit and perhaps taxis and ride hailing, car sharing, et cetera. But that's becoming a thing, if you will. And I think it remains to be seen. I think a lot of people at the margin will adopt that. One question in my mind is the extent to which we'll still want to own one, you know, have it in our driveway, have it at our disposal instantly as opposed to having to wait for a vehicle of any kind to come pick us up.

That's part of it, but cars are definitely changing, of course. So they’re becoming more talkative to each other, so the connected vehicle is a syndrome that's rapidly being developed and changing. So we're already familiar with high end new cars having all kinds of collision avoidance, lane keeping, assisted parking, et cetera. And that's only going to get more and more, which is a boon of course to older drivers and, guess what, drivers of all ages. So all of these safety features that are put into cars, you know, they may be touted as great for helping baby boomers like myself drive longer. But any such feature is also going to be useful for all ages.

So there's the connected vehicle phenomenon, and then again automated vehicles, as you know, are already in testing phases, in use in real-world applications. And so believe me, vehicle manufacturers are working day and night to see how they can build the best automated vehicle in a variety of forms. So in the future, we'll see automated trucks, automated buses, as well as automated personal vehicles potentially of all sizes. You can imagine the portfolio of the little automated car that you'll just send to pick up the dry cleaning or the groceries, the RV automated vehicle that you’ll use for the cross-country trips, et cetera, et cetera. So I'm sure the imagineers are hard at work imagining a whole range of options for us.

Steve McLaughlin: One of the things that we do keep hearing about is air mobility and, you know, like flying taxis. Uber’s been talking about air taxis, and I think I've heard something about air taxis in Dubai and experiments that are already going on. You know, when I was a kid, we’d watch things like The Jetsons and it didn't seem like that was going to happen in my lifetime. But it seems like there's a there's a good chance you think that that'll be happening—air taxis, personal flying vehicles, in the next 20 years.

Pat Mokhtarian: I completely do. In fact, for probably 20 years—OK, maybe 15—I've been saying flying personal vehicles, whatever you want to call them, are coming, and I must say my colleagues were looking at me rather strangely at that point. And of course, I was saying that again from the benefit of complete ignorance about the technology of what it takes to build them and operate them. But it just seemed to me, from my bird's eye view of the way technology was going, was that it was going to be possible. And so now of course lots of institutions and companies and so on are working toward that very thing.

So I think technologically it's inevitable, but what the challenges include are air traffic control—that's a whole can of worms. Again, I'm assured from what I read that that's solvable, but I suspect it'll take some a lot of coordination, a lot of again new technology perhaps. And of course, from a personal standpoint, as exciting as I find it—I'm one that thinks it would just be really cool to have my own personal flying vehicle—but I don't want them flying over my backyard. Right? So we now have an issue of privacy of, again, air traffic control. So I think there's going to have to be some kind of regulation.

And you know— But I think it just makes too much sense not to do. I think initial markets are probably going to be pretty high-end. So a couple of my colleagues here at Georgia Tech have NASA funding to study this so-called thin-haul aircraft market—meaning points A and B that don't have enough demand between them to justify commercial service, but, you know, there's air taxi on demand service could be viable again for a high-end market. And then also looking at the intra metropolitan area commuting. So just hop over the congestion on the 85 and just get to work by, as you say, air taxi.

So these things are certainly being studied. And, again, I think it's inevitable at some point the question will be sort of what do we need to build around it from the standpoint of balancing competing interests. On the one hand we want to get there fast, on the other hand you've got to respect privacy, property rights, that sort of thing.

Steve McLaughlin: I know one of the things that you've worked on quite a bit is the effect of telecommuting. You know, many people believe that telecommuting—the idea of working from home one or two days a week—saves on gas or commute hours, you know, and produces productivity. But your research, I think, shows some surprising results. Can you share a little bit about what you've learned around telecommuting?

Pat Mokhtarian: Yes, that's interesting. I started studying telecommuting back in probably 1982 when I was working for a regional planning agency in Southern California who was interested in “Will it be a meaningful solution to our congestion, air quality problems, and so forth?” And at first I was quite enthusiastic thinking of course it will be. As time went on and I started doing more and more rigorous research, I tempered my enthusiasm quite a bit. And I want to stress that I still think telecommuting, per se, on net is a benefit to transportation.

But what we found was that not as many people wanted to telecommute as who are able to, you know, so even if your job permits your manager may not and that's still a big barrier to this day. But even if your manager does, the individual may not want to. And we are like, well, why? And it turns out, number one, people like the social interaction of the workplace. Number two, they may like the amenities of the workplace. So they like working in a vibrant lively downtown as opposed to sitting on their tushy all day at home and, you know, not getting any exercise and so forth.

And then it turns out that not everybody has a terrible commute. So again, we have a stereotype in which, oh, commuting is awful and everybody looks at the evening news or listens to the radio report and thinks “Well I must be the exception, because obviously everyone else's commute is terrible.” But people adapt. They choose residential locations that are as close to work as they can get, taking other considerations into account. Not all of their trip is on a congested highway, and so on. And so more general population polls have found, when you ask them, you know, is congestion a big problem, they say “oh yes” by large majorities. When you say “is it a problem for you personally?” Often fewer than half say yes.

So if I have a pretty straightforward commute, or perhaps even a pleasant commute, which we also found—you know, some people say “You know, I like my commute. It's me time. It's time I can get ready for the work day or process what happened during the day on the way back home” and so forth. So, if you're one of those kinds of people for whom the commute is actually positive, you're also not going to want to telecommute.

So all of those factors, I think no single one by itself perhaps, but together have resulted in telecommuting not being adopted as widely as we expected. Still, it has grown and to some extent has become commonplace. So I think what was experimental and viewed with suspicion at the beginning is often now taken for granted. And you mentioned the millennials earlier. One stereotype, again if you will, about them is that they demand or at least expect workplace flexibility. And I think that's helping also to change the climate in terms of reluctant managers may be coming around because that's how they're going to keep employees.

And so I think over time it will continue to increase, but possibly not much more beyond where we are now. There may be sort of a natural level of equilibrium that we either have already reached or may be close to reaching. Sometimes people say “Oh, if we just had better technology.” We've always had technology that permitted more telecommuting than took place. And so I think it's more the personal considerations, the social, the managerial or institutional, than the technological ones.

Steve McLaughlin: As we've already said, it's hard to imagine a more relevant topic for public today because they hear so much about it, but we don’t always think of this as the work of an engineer. We think of city planner or someone who works for the Department of Transportation, you know, as being interested in the kinds of things you're interested in. Can you say a little bit more about why would an engineer do this kind of work?

Pat Mokhtarian: Yes, the issues are way beyond engineering, so that's one of the things that fascinates me and attracts me, and I think to a large extent my students as well. Transportation has historically been interdisciplinary, so in some ways we've long been a misfit, if you will, in kind of the more traditional engineering disciplines. So, of necessity, we've had to reach out to other disciplines such as urban planning, geography—in my field, psychology, sociology, anthropology, certainly economics.

And so when I look for students, I look for students— if they have those kinds of backgrounds, I'm even more intrigued. Obviously though they need the math. I was a math major and loved it and I was given the best advice ever when trying to decide on a major, which was “From math, you can go anywhere.” So I use quantitative methods in my work and expect and need my students to be very adept at quantitative methods as well. A big thing nowadays is machine learning in a variety of fields and including ours.

So there are a number of applications in transportation. There have been fewer in travel behavior, but this is one area that I'm getting into, somewhat to my own surprise. I didn't expect me to be doing that five years ago. But one of the things I'm trying to do is to use machine learning to impute attitudinal data into travel behavior data sets. So we use regional travel demand forecasting models and, you know, ARC does it, the Atlanta Regional Commission, and any metropolitan planning organization in the country. Those models are typically calibrated, if you will, estimated on datasets that are basically a roster or diary of people's travel behavior over a period of time—typically one day, sometimes longer. So we use information like travel times and travel cost of the trip alternatives together with demographic information to model or try to predict what people will do.

To me, for a long time, I've thought “Where are the attitudes?” Because if you think about our own choices, attitudes are fundamental to the decisions we make, and you will never find an attitudinal variable in any of these regional models and for a couple of good reasons. One is how do we forecast them? So to apply a regional model to look at what transportation will be like in 2025 or 2040, you'll need to predict the input variables that far into the future. And if you're talking about an attitude, who knows what they'll be. And that's a legitimate concern.

Another legitimate concern is how do we measure them now even? They are harder to measure than behavior. Just ask somebody what trips you made yesterday and that's pretty straightforward, but ask about attitudes and there are more challenges associated with it. But we do know how to measure attitudes. We do know how to incorporate them into models. I've been doing it my whole career. So this latest brainchild is to try to use the attitudes that I've gathered in my smaller scale specialized surveys, and can we use machine learning techniques to estimate the attitudes of the respondents in the travel behavior data sets. If we can do that successfully, we can start incorporating attitudinal variables into the models that use those datasets.

So that's gotten me excited. My students are excited to be using machine learning methods to analyze attitudes and behavior, and to hopefully over time improve regional travel demand forecasting models. Because, right now, they can't keep up with all the things we've just been talking about—automation, ride-hailing. None of these things can really be handled well by today's models, and we need to improve them so that they can.

Steve McLaughlin: Particularly as it relates to how much Atlanta has changed or where it needs to change. If you had a crystal ball, what do you think the Georgia Tech campus or Atlanta will look like in 10 or 20 years from now?

Pat Mokhtarian: I'd love to see more accessible transit service, meaning greater accessibility to buses even, certainly rail. So more frequent service and so on. But that's of course very challenging. It's very expensive. If you just have buses running on the same congested roads as the cars, then it's a chicken and egg problem. They can't really provide faster trips. Indeed, it will be slower because they have to stop and pick people up. So you know, it's hard to get a level of service on transit to attract choice riders as opposed to captive riders, as we call it.

So I think that's the ideal to have better collective means of transportation, but it's really hard to achieve. You know my husband’s son in southern California would always tease me saying “How come you haven't solved our transportation problems here in Los Angeles yet?” And I would say “How come you're still driving?” So the problem is that we've met the enemy and they is us, right? We are all the problem if we drive, as I admit to doing.

And that is the challenge. You know, people talk about the love affair with the automobile in the US and that always sort of irritates me because I don't think we're all irrationally, emotionally attached to our cars. Rather, cars are still pretty darn convenient ways of getting around and doing the complicated activity agendas that most of our lifestyles involve these days.

So it's going to be pretty hard to compete with a private automobile. However, I think there are certainly corridors or origin destination pairs, if you will, that could be better served by transit. And I think that information technology can help us identify those origin destination pairs and, over time, provide kind of the right sized service, if you will. So instead of sending a bunch of large buses around empty, maybe we need smaller vehicles but more of them and serving more pairs, if you will.

So I'm hoping that transit will evolve in that direction, but it's really hard to turn around the cumbersome systems that are often in place now with legacies from the past. And I'm not speaking of Atlanta in general, lest I offend anyone listening. But just I think it's really hard to take a traditional service that's been operated a certain way and try to be nimble about what the future might bring.

Steve McLaughlin: Well, we can't thank you enough for your time, Dr. Mokhtarian. I want to ask you one last question that we ask all our guests here on the Uncommon Engineer What makes you an uncommon engineer?

Pat Mokhtarian: Now that's really a trick question because I'm afraid whatever I say there will be lots of engineers out there who say “Well I'm that way! That’s not so uncommon.” So what I'm going to do is just say what I think some of my strengths are and let the listeners decide how common it is or not. But I think one of the things I do is read widely and draw inspiration from a variety of different sources.

One of my streams of research that I was more active in in the past than I am at the moment but I still want to pursue is the idea that travel itself has a positive utility. And you know, in all of our models we assume that it's a disutility, as the economists say. Something we want to minimize, do as little as possible. But you know, I and my colleagues realized that actually we’re born to move. If we're not moving we're dead. And that in many ways travel is something that we do for its own sake, not just to get from A to B. And when I was doing some early research in that area I was just thrilled because it was taking me into classical literature and popular music and physiology, law, all kinds of fields that we don't normally tap when we study transportation.

And so I feel like that is again the exciting thing about transportation to me is that it's connected to virtually every discipline imaginable. And we need to reach out more across disciplines and learn from what, you know, anthropology can teach us and what physical science can teach us. So that's one thing and I just love reading and writing. So again, I know that that's not all that uncommon, but I like probably many of us have had the occasional students say “Yes, I'm majoring in engineering, so I won't have to write.” And I always groan and say you're in for a shock. So I've loved reading from childhood. I love words—playing with them, working with them, getting a point across persuasively or, you know, conceptualizing a framework in a way that hasn't been thought of before. And so for me it's exciting to be paid to do this kind of thing.

Steve McLaughlin: Well thanks so much. Your work is absolutely fascinating and it couldn't be more relevant for today's world. We really appreciate your time. Dr. Mokhtarian.

Pat Mokhtarian: Thank you very much.

Steve McLaughlin: For our audience, tune in next time. We'll be talking to Professor David Hu and his work with the relationship between animals in engineering and the things that we can learn from them.

Train Announcer: This vehicle is leaving the station. Please hold on. The next stop is Concourse B. The color-coded map and signs in this vehicle match the station colors.

[“Ramblin’ Wreck from Georgia Tech” music]


Audio & Captions

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[analog radio tuner scanning stations]
[big band swing rendition of Ramblin' Wreck from Georgia Tech]
[interposed voices of Steve McLaughlin] ...sounds incredibly sounds have abilities that span...I'm really geeking out here.
[applause and laugh track]
[big band swing rendition of Ramblin' Wreck from Georgia Tech]

[race car sound]

Pat Mokhtarian: The interstate driving is the part that's tedious, that's boring, and that's often easy. Now, even easy has challenges with weather, with road construction, with the unexpected. So nobody's saying, “I think day after tomorrow might be a little premature,” but that might well be the first application to be in widespread use. And even then, one would have to imagine that you're going to have the interstate segment that may be automated, but when you're driving in town, you need an alert driver with hands on the wheel at least, again, for another decade or two after that. So it will be phased, and that's part of the interesting challenge as well—how do we get from here to there so we can imagine or start to imagine a fully automated vehicle future? But there are a lot of pathways between here and there, and that's really kind of a challenge right now.

I was learning about travel behavior models in graduate school. And at that time it was most common that the explanatory variables, if you will, in those models—the typical factors that explain people's behavior about travel, in particular, are travel time and travel cost—we want the shortest trip possible and the cheapest trip possible. And we'll throw in some demographic variables because maybe income affects things, all else equal or gender or household size, that kind of thing—vehicle ownership.

But again I was realizing that, well, attitudes ought to be in there somehow. And I learned through taking courses in marketing research and psychometrics that there are well-established ways of measuring attitudes. Now, there are lots of pitfalls in doing so because, as you can imagine. For one thing, people don't even articulate to themselves, sometimes, what their attitudes are. So when you give them an attitudinal statement and ask them to strongly disagree, to strongly agree with it, they may be, for the first time, trying to figure out what their position is. So there's a certain amount of volatility in the attitudes that people report having. And also, there are all kinds of subtle biases: There's the social desirability bias, so they may want to look pro-environmental whether they really act that way or not. And in some cases, again, they don't even realize themselves that they're kind of projecting a persona that otherwise may not fit them. But there are techniques in survey design—and I teach a graduate class in survey design methods—so there are lots of little tricks to help reduce those biases; we don't necessarily get rid of them entirely. But a well-designed survey, I think, can go a long way toward eliciting at least a kernel of truth, if you will, about people's attitudes.

So when I design a new survey, I just give a lot of thought to what I think the important variables are given whatever behavior I'm interested in analyzing whether it's telecommuting adoption or the adoption of a ride-hailing alternative, and the future automated vehicles of course. So what are the, you know, the characteristics of the alternatives that are important? So those might be the more objective variables, if you will. But also, what are the attitudes that are important? And then we spend tons of time writing attitudinal statements, refining them, pretesting them, getting enough of them to kind of triangulate, if you will, on an attitude of interest, doing that for multiple attitudes of interest. And so it's a long process that I think is often underestimated. I try to teach my students in the class that you can't possibly do justice to a really good attitudinal survey in a short amount of time. And so, but having said all that, it's served us very well over the years. I think we can do a respectable job of measuring attitudes of incorporating those measured attitudes as explanatory variables into models.

[car engine revs, car horn]

Another thing that I realized early on in graduate school was that we'll never be able to predict behavior with certainty. So again, that's one of the fascinating things about people is that they're so unpredictable. And what I loved was that I was learning about probabilistic models. So the whole point of these models is not to predict what people will do, but rather it's to predict what's the probability that they will do this as opposed to that as opposed to that. So it just resonated with me that these probabilistic models really fit our inability as analysts to ever know with certainty what humans are going to do. But we can increase the skill that we have in predicting what they will do i.e. raise the probability that will predict the action that they ultimately take.

[transportation terminal sounds]

That has been very heartening to see the increased level of support for transit and in some counties that historically, at least on net, had not been supportive of it. And that may be partly a millennial influence as well. Certainly I think a generational shift in how transit in general is perceived and in Atlanta in particular. So I think there's a much wider spread understanding now that we need it throughout the entire metropolitan area and not just in Fulton County or the surrounding inner suburbs if you will. So that is exciting.

I hesitate to give much advice to people who are out in the trenches, and I think they're already aware of the kinds of things that need to be done. I'm delighted to see more attention being paid to bicycle infrastructure, to making locations more pedestrian-friendly and more mixed use so that we have more activities to walk to or bike to. So I think that's also a thrilling development here in Atlanta and around the country that in the past car was king, and they got first priority and everything else had to wait in line. Now I think much more attention is being paid to the entire portfolio of transportation options and the need for having bike when bike is appropriate, and being able to walk when walking is appropriate.

I think most people are not going to walk everywhere they go or bicycle everywhere they go, but just having the option would be so refreshing. And in many cases, there aren't sidewalks or there, you know, the sidewalks are broken and impassable or discontinuous—so you get on one for a little while and then suddenly you have to cross a busy street to get to someplace where you can keep walking. So we have a long way to go but it's really reassuring that some funds are going to be devoted to the problems we have.

Another area, of course, is making transit more attractive again to the choice rider. I think more could be done with station area development and attracting people to transit stations almost as destinations in their own right, but certainly as interesting and effective places to hang out for a little while and, of course, outfitting transit vehicles to make it easier to work on them or to use the time in other meaningful ways would also be helpful.

[traffic noises, traffic reporter]

[Ramblin' Wreck from Georgia Tech marching band rendition]