MS. SUSAN PAGEThanks for joining us. I'm Susan Page of USA Today sitting in for Diane Rehm. No matter how good the bike lanes, metro rail or bus lines are in your city, undoubtedly you see a lot of cars on the road. Well, cars aren't going away any time soon, sustainability experts see a future where urban centers are less dependent on auto use. To talk about the trend and what it means, I'm joined in the studio by Peter Newman. He's the author of "The End of Automobile Dependence," and a professor in Australia of sustainability. Thanks for joining us.

MR. PETER NEWMANThank you, Susan.

PAGEJoining us from the studios of KQED in San Francisco, Emily Badger of The Washington Post. Welcome, Emily.

MS. EMILY BADGERGreat to be here.

PAGEAnd joining us from the studios of NPR in New York City, Robert Puentes of the Eno Center for Transportation. Welcome, sir.

MR. ROBERT PUENTESThank you, Susan. It's a pleasure to be with you.

PAGEWe invite our listeners to join our conversation and maybe their own experiences with transportation in the city they live in. Our toll-free number 1-800-433-8850. You can send an email to drshow@wamu.org or find us on Facebook or Twitter. Well, Peter Newman, let's start with you, your new book. It's called "The End of Automobile Dependence." Not the end of automobiles, but the dependence on them and you argue that we are at a kind of turning point.

NEWMANYes. It is a turning point and Robert Puentes actually was one of the first to see that peak car was happening, that car use per capita was going down. Now, we have been collecting data on cities from around the world and comparing them for 30 or 40 years and we were a bit surprised that hit happened so quickly. And then, we found that virtually every developed city, including not only in Australia, but certain European cities, Japanese cities and so on. And even more recently, now, we can say in Beijing and Shanghai, car use per capita is going down.

NEWMANAnd in some cities, that means total car use is declining as other modes are favored and more importantly, as cities come back in and people don't need a car as much.

PAGERobert Puentes, you just got a shot out there for noticing this trend first. Tell us what you saw.

PUENTESWell, the one constant that we've had for years, particularly here in the United States, was increasing driving. Year after year, as America grew, post-baby boom era, post World War II, Americans drove more and more and more. It happened year after year after year with little blips during recessions. And then, a few years ago, maybe 10, 15 years ago, a little bit longer than that, we start to plateau a little bit. That kind of leveled off. Then, we had the Great Recession and it completely feel down.

PUENTESAnd so driving, even on an aggregate basis, was declining overall. Now that we've kind of -- the economy has recovered, it's increasing now again a little bit, but we have certainly moved away, as Peter was saying, from the one constant that drove, no pun intended, the stats for years and years, which was American's gonna drive more and more and more. When you look at what's happening her in the U.S., when you look at other developed countries, it's the same trend. We've kind of plateaued as economies grow.

PUENTESThere is some more driving going, as the country grows, but the changes that have happened from generation to generation are dramatic.

PAGEEmily, you cover urban policy for The Washington Post. Do you see this playing out in cities?

BADGERYeah. I mean, I think it's absolutely true that the vast majority of us are still dependent on cars. I mean, if we look at census data, for instance, 86 percent of people get to work every day in a car, 76 percent of people get to work every day in a car that they drive alone. It has nobody else in it. So, you know, a tremendous number of us are still relying on cars, but I think the question that a lot more people are starting to think about is, well, how many of those people actually want to drive a car?

BADGERYou know, is the fact that all of those people driving, does it mean that Americans love cars? Does it mean that this is how they would really prefer to have their commute set up? Or is it the case that so many people are driving because they don't have other options, you know, because we've built this environment around us since World War II that basically means that public transit's not an option for many people, bike lanes don't exist for many people? You know, many people may not be able to afford a house that would be within walking distance of their job.

BADGERSo, you know, to me, what I see changing and changing much faster than the statistics is this mentality that says, you know, what if we created other options for people and would people's behavior change if we did?

PAGEEmily, you just said 86 percent of Americans go to work in their car. Is that right?

BADGERYes, that's correct.

PAGESo tell me, on a typical day when you go to work, are you going to work in a car or some other way?

BADGERI go to work in a bus, but you know, I live in San Francisco and I previously lived in Washington D.C. and these are two environments that are not at all typical of where the vast majority of Americans live. You know, these are cities that have fairly good public transit systems and, you know, I hear from a lot of readers who say, well, that's not where I live.

PAGESo Emily goes to work in a bus, Robert. How do you go to work?

PUENTESI'm fortunate enough to live in the suburbs of Washington where we have metro rail service so I'm able to bike to the metro rail station. I work downtown.

PAGEAnd then, you take metro in, although metro's been a pretty troubled system. And Peter Newman, you live...

PUENTESIt has been challenging.

PAGEYes. In Perth, Australia. How do you go to work?

NEWMANWell, I used to ride a bike to go to work and then, our university took our institute and put it way up in the suburbs so now I drive. So it's a car-dependent location and I could take the bus, which would take an hour and a half, but by car about 40 minutes.

PAGESo I go to work in a car, but I have to say I have two sons who live here in Washington as well. One of them typically rides his bike to work, although it's uphill going home. I respect him for that. The other one just gave up his car and now takes the bus to work. And I wonder if there's a generational shift that's part of this, Peter, that millennials are more willing to give up their cars.

NEWMANYes, the data is very clear on that. The people in their teens, 20s, 30s, 40s, even 50s are driving significantly less. When you get to the baby boomers like me who grew up with the car, essentially their freedom and connection was all about getting in a car, we're driving more. But we're disappearing. We're actually driving to our own funerals.

PAGEEmily, do you think there's a generational dimension to this? You mentioned, of course, accessibility to public transit. Of course, that's really important. But is there a generational aspect to it as well?

BADGERI think there's a generational aspect that's also economic, in part. I mean, millennials are a generation that, you know, those who went to college have tremendous amounts of student debt. Those who are living in expensive cities like San Francisco or Washington or New York are paying way more in rent than their parents were at their age and, you know, it's just kind of a financial reality for a lot of people that, you know, if you're going to spend all of your money on your rent and on the cost of living in these really expensive places or you want to spend all of your money, you know, going out to eat or going to bars or something, you know, one of the best ways to sort of scrape some money out of your budget is to not own a car.

PAGEAnd, of course, the recession probably exacerbated concerns about the cost of keeping a car. How important is that, Peter? How important is this trend -- how much is this trend related just to the Great Recession?

NEWMANWell, I'd have to say not as much as perhaps most Americans would think because in Australia, we were hardly affected by the recession. It was -- we weren't, actually, in recession. And in my city, it was a boom time in Perth. We had a massive increase in our exports that were going to China and that Perth was the great growth center at that time. So we had 500,000 people come in seven years to our city.

NEWMANAnd yet, per capita car use went down even faster, actually, because there were a lot of young people coming to the city and they wanted to live in locations where they didn't need a car. So there's a very strong cultural theme and the reality is we're running out of those areas where they have come to live where there's a lot of condos designed for them to live and we need to -- if we're going to keep this process going, we need to actually create more of these urban environments that are transit oriented.

PAGERobert, you see this as part of a bigger conversation about inequality. Tell us how.

PUENTESWell, I think Emily was starting to get this and this is the conversation that we need to have. As we're building these cities and retrofitting our suburbs for other modes beside the car, we have to ask ourselves, well, for whom and how does increasing bicycle, for example, in the inner cities -- that certainly is helping many, many people. Is it helping everybody? Is it helping particularly people that need it the most? As the other panelists have said so far, the demand for living in transit rich areas is almost insatiable in a lot of parts of the United States.

PUENTESThat means, though, the cost of living in these places is very, very high. And so Americans in the lowest 20 percent income bracket spend about 42 percent of their total annual income on transportation, compared to 22 percent for the average middle income American. So when we think about getting people out of their cars and we think about providing option, these are good conversations to have, but we have to make sure that this isn't restricting folks and preventing upward social mobility.

PUENTESThere's a very famous study a few years ago that showed just this very thing, that upward mobility is strongly dependent on the access for transportation, for a range of transportation options. So when we think about -- we think about segregation. We talk about public housing. We talked about insurance red-lining, all these very famous things, but transportation has always been off the hook for now. So as we think about what the United States looks like post car, we've got to make sure we're thinking about it on the broad ends of the economic spectrum, not just for different segments.

PAGEAnd given the cost of housing in places that have good public transit, it means that the more money you have, so the more you could afford a car, perhaps, the less likely you are to need a car in these situations. Is that right?

PUENTESIn some cases. As has been said, you still need, probably if you have a car, to travel to maybe suburban locations. There are many households that may have two-income earners. One might work in the city, one might still work out in the suburbs. So I don’t think that the need for the car is going away, but there's a great quote, I think, in Peter's book where he says that a car is a great servant and a lousy master.

PAGEAll right.

PUENTESSo I think we're having this big conversation, it's really about the how do you make sure that it's not the only way that cities and metropolitan areas are functioning, it's not the only way to provide accessibility to places.

PAGEAll right. We're going to take a short break and when we come back, we're gonna go to the phones and take you calls, 1-800-433-8850. Tell us about your own experiences. Stay with us.

PAGEWelcome back. I'm Susan Page of USA Today sitting in for Diane Rehm. Joining us from the studios of KQED in San Francisco is Emily Badger. She's a reporter who covers urban policy for The Washington Post's Wonkblog. And joining us from the NPR studios in New York City, Robert Puentes. He's president and CEO of the Eno Center for Transportation. And here in the studio with me, Peter Newman. He's author of "The End of Automobile Dependence: How Cities are Moving Beyond Car-Based Planning." And he's a professor of sustainability and director of the Curtin University Sustainability Policy Institute in Perth, Australia.

PAGEPeter, before the break, we were talking about the issue of inequality and how it factors into this discussion about cars and their use in cities. What do you think?

NEWMANYeah. I've written a few books and one of them with Island Press was called "Resilient Cities," in which we posed four possible city forms. And the divided city, explained as being eco enclaves surrounded by Mad Max suburbs, and that is what is happening in Australian cities. In many ways, the rich are now using cars far less than the poor. The -- there are increasing numbers of people who have three, four, five cars in their houses in the outer suburbs. And the wealthy don't need to drive at all because they're in transit-rich areas with lots of local activity.

NEWMANAnd the American cities had to go through this process of urban regeneration, because many of the inner, old transit-rich areas were very poor and rundown. And you've been through that very quickly. And it's a question now of how to retain some affordable housing there as well as building new, transit-oriented developments in the suburbs, so people everywhere can have transit-rich areas.

PAGEEmily, how do you see this affecting the work of city planners and how they think about what the goals are when they -- developing plans for cities?

BADGERSure. Well, you know, I think some of the strongest evidence that we have that people value transit and people value walkable environments is that property values in these areas are rising faster than they are just about anywhere else. I mean, if you live in Washington or Chicago or New York, you know, you're familiar with this phenomenon that rents or housing values are much more expensive if you're within walking distance of a subway stop or an el stop or a metro stop.

BADGERAnd, you know, for planners, this raises the question of, well, you know, if there's so much demand for these types of environments near transit, where people can walk, you know, where they can get to the grocery store or drop their kids off without having to get in a car, you know, that suggests that we don't have enough of these places and we need to build a lot more of them. And we particularly know that we don't have enough of these places if there are bidding wars going on there that are driving up housing costs to the point where, you know, middle-class, working-class, lower-income people can't afford to use them.

BADGERBecause, you know, as you mentioned earlier, those are precisely the people who need the most to depend on transit or, you know, to depend on being able to walk places, so that they don't have to have the expense of a car.

PAGENow, Sheldon has a comment, I think, that might relate to this. He's calling us from Polk County, Fla. Hi, Sheldon.

SHELDONGood morning.

PAGEGood morning.

SHELDONMy question is, what do you do when the urban planners in the area see a need for expanded mass transit and every time it goes to a referendum, the people vote it down?

PAGEAnd, Sheldon, let me ask you -- you're in Polk County, Fla. -- do you have easy access to mass transit yourself?

SHELDONWell, no. And I live in -- we are pockets of residents and so forth in small cities but there's miles separating. I live three and a half miles from the grocery store. So that's the nature of development in Polk County. It's isolated pockets of development separated by miles of highway.

PAGEAnd I assume that means you have a car.

SHELDONOh, yeah. I'm talking to you from it.

PAGEAll right, Sheldon. Thanks for your call. Peter.

NEWMANThanks, Sheldon, who lives in a car. I've just come back from Florida and I was very impressed by the groups of people who are now working on how to transform that whole corridor from Miami to Orlando. I was privileged to be shown the new Brightline rail project, which is totally private and will be built by using land development opportunities around stations. Now this is something that we've been pushing for some time. And the reality that Robert and Emily have said, of demand for this kind of housing and this ability to live in a place which is less car dependent, means that we can now involve the private sector in helping to fund it. We don't just have to use governments.

NEWMANAnd governments just don't have enough money to meet this demand. And it's a far better way to do it, because the private sector actually builds cities. We need to build around transit. Now, for the first time, we've got a company that's building transit and transit-oriented developments around the stations and making that a model where they can take it to the rest of America. I think it's very good news. And we want to see this in cities around the world. We've got people starting to think this way in most other cities. But this is the first time I've actually seen a project which is going to be opening next year.

PAGESo if that works, another model for providing mass transit. But, Robert, back to Sheldon's original point. Is it a problem that referendum come up and voters vote them down because they don't want to pay the cost of mass transit?

PUENTESWhen you -- actually, when you look nationally, it's almost the opposite of what Sheldon was talking about. I don't doubt that it's true in Florida. I think Tampa famously rejected a referenda a few years ago. But when you look around the country, particularly in the West, particularly Intermountain West, it's the opposite thing. And we're continually going to the voters on election day and these things are passing -- 75, 80 percent of these are passing. And it's the number one way that many cities and metropolitan areas in that part of the country are reinventing themselves -- places like Denver and Salt Lake City, Phoenix.

PUENTESLos Angeles did it right in the middle of the recession, when unemployment in the county was 22 percent or something. You needed two-thirds of the vote to pass it and Los Angeles got it, they passed it. They're going back to the voters again this November with another gigantic sales tax measure to pay for all kinds of different transportation improvements, mostly on transit. Seattle, I think, San Francisco, Emily, as well. But -- so this, what's happening in Florida -- it's a big country, you know, things are different.

PUENTESBut it's almost the opposite nationally, because we have a federal government that is not providing the resources that folks need. We have $86 billion or something like that in shortfalls. The cities, the metropolitan areas, are pulling themselves up. They're going to their voters themselves and they're raising the money locally.

PAGEYou know, it's interesting, Los Angeles -- it's hard to think of a city that seems less friendly to mass transit and friendlier to the car than L.A. Is that changing, Emily?

BADGERYeah. I mean, Los Angeles I think of as, you know, one of the cities that is doing the most to invest in public transit right now. And I was actually in Los Angeles just a couple weeks ago and was riding a new light-rail line, the Expo Line, that just opened up not that long ago, that connects the center of Los Angeles all the way out to the coast by Santa Monica. You know, it's like an hour-long train ride, but it's providing connectivity that didn't exist before. And Los Angeles we all think of as like the poster child for highways, for sprawl, for everybody there owns a car, everyone gets around by car. But the fact that, you know, they're making a major push on transit there I think should be encouraging for a lot of people.

PAGEYou know, Houston another place that we think of as being a city that you'd better own a car if you're going to live and work there, what do you see happening there, Robert?

PUENTESThe -- Houston's great story is that they -- again, giant, giant metropolitan area, historically very sprawling -- they've recognized the concentration of resources in the downtown. They've got a rail connection down there. They're concentrating a lot of growth and development downtown around the medical center and some other areas down there. But what they've done is they've reimagined their bus system. And so we've talked a lot on this show so far about rail and that certainly is a big component.

PUENTESBut buses are still moving an awful lot of people. And they've gone down there and recognized that the bus system can stop focusing on providing insufficient services to lots of different neighborhoods and just concentrate on those high-capacity corridors where you can really get the best bang for your buck. And they move -- I wish I had the stats -- but tremendous numbers of folks, particularly from the outer suburbs going downtown on buses every day. They have dedicated lanes. They have super-fast services. And I think the lesson that we're going to get from Houston is less about the rail system than what they've done to reimagine bus service.

PAGEWell, here's an email though from Evan who writes us from Fayetteville, Ark. He writes, I live in a sizeable, middle-American metro area of about 500,000 people in northern Arkansas and we still live with the reality of near-zero public transportation and high amounts of pushback for a light-rail project. So what can somebody like Evan do? Peter, what are the alternatives for people who live in a city where you don't see this kind of effort made to provide more public transit?

NEWMANMost of my books are written for people like you. They are meant to change our cities. They are for activists to be able to use to provide the data of the stories of encouragement of how cities have changed by small groups of people. Because I had that in my experience myself. I was a local government councilor when the railway system was closed down in my city. And I helped to organize the friends of the railways. And surprisingly enough, the group of 12 or so of us won. And the government was thrown out and the railway brought back. And then for the next 20 or 30 years, we've been putting extra rail projects on the agenda and winning them constantly.

NEWMANSo you can change a city. You have to be smart. You have to be committed. But you don't need more than a dozen or so people to get together and dramatize the issue and get on with it.

PAGEBut, you know, you have -- this is actually the third of a trilogy, this new book that you have, "The End of Automobile Dependence." You got a huge reaction in America to the first book in this series. What happened?

NEWMANWell, we started off, because I started winning projects back in the '70s and '80s, to write up books about it and to put together data comparing cities around the world. And we found that there was, in America, almost violent emotional reaction to our findings that American cities were the most car dependent. So one group of people from the University of Southern California said that we should give up our futile attempt to enforce urban compactness and we should seek another planet, preferably unpopulated, where we can build compact cities from scratch with solar-powered transit.

NEWMANAnd this was meant to -- I mean, this was in a formal academic journal that they were writing. And there was clearly a lot of anger that we would try to attack this American icon, that you build cities around cars. But you just don't find people anymore who say that's what you need, that American cities should be more car dependent, should sprawl out more, should have less public transport. I mean, that's disappeared off the agenda. So clearly we're winning the debate. Whether we win it politically is -- well, it's a big question. And, as Robert said, things are happening.

PAGEEmily.

BADGERYeah. I was just going to add that in my experience, particularly interacting with readers when I write about this, that I think there's more pushback perhaps than Peter has experienced or is mentioning. And it doesn't just exist in Fayetteville, you know. It exists in Washington, D.C., too. It exists in New York City. And, you know, part of it stems from this idea that transportation is sort of zero-sum in a sense. So whatever we invest in transit, we're not investing in highways, or whatever bike lane we put in the street, that means we're taking space away from cars. And, you know, there's a lot of tension there. And I think, you know, a lot of people who depend on cars and may even like driving their cars feel sort of threatened by this.

BADGERSo, you know, to me I think there is real sort of tension and conflict here, you know, not just sort of a smooth, easy transition into, you know, let's all ride transit more.

PAGEI'm Susan Page and you're listening to "The Diane Rehm Show." Let's go to the phones. We've got a caller from Graham, N.C., named Jo. Hi, Jo. You're on "The Diane Rehm Show."

JOHi. Hi, thank you for taking my call.

PAGEYes.

JOYes. I drive for a living, so I have to be in a vehicle all the time. However, when I'm not on the road, I will keep my vehicle. I will never be without a vehicle. In the past, I have been homeless and in areas where transportation -- public transportation is unavailable or unattainable because of how much it costs. At one point in time, the only way I was able to actually get public transportation was to go to college and my bus -- my college I.D. became my bus pass. And I just will never be without a vehicle.

PAGEInteresting. Do you -- you say you drive for a living. What do you do?

JOYes. I expedite. I'm like a courier. I take everything across the whole eastern side of the country.

PAGEAll right, Jo. Thanks very much for your call. What do you think, Peter?

NEWMANWell, I think it's a bit sad that you don't have real options, Jo. It's -- it is -- nobody's going to get rid of your car. Most families will have car long into the future. But you don't need to have to use them the whole time. Many people will live without a car. But they won't have to actually buy one in order to survive. It sounds as though your experience is such that you couldn't possibly imagine living without a car. It doesn't take a lot of other options to change the quality of a city. And when you go to a European city, for example, most families still have a car but they don't need to use it. So the quality of the city is very different.

PAGENow how do you -- so, what -- how does the quality of a city change if car use declines significantly?

NEWMANWell, there's significantly more people walking and cycling. And there's a lot more activity around that isn't car dependent, as well as the fact of just going to work and so on. And that activity is increasingly what our cities are about. We want opportunities and be able to get to those opportunities, whether they're education or health or work. We need to be able to do that simply and easily. And the walkability of a city is increasingly being measured. Seventy percent of the knowledge-economy workers in Boston live in walkable areas. Thirty-eight percent -- sorry, the six most walkable cities in America have a 38 percent higher GDP.

NEWMANIt is increasingly being found that the quality of the city in its walkability defines how well capital is attracted to the area and also how people want to be there.

PAGEAnd how do you define a walkable city?

NEWMANWell, it's increasingly being measured by particular indexes and you can compare them when they have livable cities comparisons that are spread around the world. And Melbourne is the latest to be number one on that. And Copenhagen and Stockholm and so on, they're very high on it. They are essentially, how easy is it to walk to destinations, in the surveys done as well as being able to measure it physically. And that walkability is a factor that draws tourists. It draws most of us to these cities. And it -- and what I found in Florida, for example, I could find many walkable town centers in Florida. And they're trying to build on that.

PAGEWe're going to take a short break. And when we come back, we'll go back to the phones. We'll take some of your calls and questions. Stay with us.

PAGEWelcome back. I'm Susan Page of USA Today, sitting in for Diane Rehm, and we're talking this hour with Robert Puentes of the Eno Center for Transportation, Emily Badger from the Washington Post and Peter Newman, author of "The End of Automobile Dependence." And we've been taking your calls and questions about your own experience with getting around America's cities. Let's go to Roanoke and talk to James. James, you're on the air.

JAMESHello, thank you very much.

PAGEYes, thanks for calling.

JAMESI'm looking to point out that I'm a cyclist who, you know, who does have a car but doesn't -- considers using it a sin, actually, and I'll use it to earn money, but other than that, I -- my default transportation is to using a bicycle, and I play my life around it. I have chosen where to live and where to work as a result, and I'm -- I know that there's a lot of other people that would love to be able to live their lives through bicycles but that they just don't know how. The school of learning how to ride a bicycle is the school of hard knocks, and people -- you know, there's a lot of people that just have, you know, confronted riding in traffic and tried what they thought was the right way and realized that they're going to get themselves killed.

JAMESAnd so, you know, they just go away from it, and you never see them again. I really wish there was another way of being able to educate the general public as to the proper -- being a part of traffic when using a bicycle, and that would really open up a whole great wide world of transportation options for a whole lot of people.

PAGESo James, you call it the school of hard knocks. Have you had some hard knocks yourself as you bicycle?

JAMESWell yeah, you know, I've kind of learned how to, you know, signal -- when the EMS worker asks me how many fingers, you know, and he holds up two fingers, I say yes, the square root of four. So I've gotten into a routine. So I know -- I know about how, you know, things, you know, happen. And I'm lucky to have learned from the League of American Bicyclists and become an instructor on how to ride in traffic. So I have some idea how to do it, and I've managed to survive, you know, over, you know, 40 years of cycling 100 miles a more each year. So yeah, I think I know what's going on.

PAGEAll right, James, thanks very much for your call. Emily, is this -- how big of an issue is this, is the safety of bicyclists and the relationship between drivers of cars and bicyclists?

BADGERI think for many people the difference between being comfortable on a bike and not being comfortable on a bike is whether or not there's infrastructure for you. You know, is there -- is there a bike lane? Is there a protected bike lane where you are physically separated from the cars. And, you know, to me the solution if we would like to have more people biking is not so much that we need to teach people how to sort of better manage, like, traffic combat with cars and sharing space with them.

BADGERYou know, I think the onus should be less on, you know, people to become comfortable learning to cycle and should be more on, you know, governments and the public and whether or not we're providing infrastructure for these people. I mean, we provide infrastructure for cars, we provide infrastructure for transit riders, and cyclists need the same thing, too, and increasingly we're seeing more cities invest in this type of stuff. But anyone who cycles around even a bike-friendly city like Washington will tell you, the bike lanes don't connect to each other, there aren't as many of them as I would like.

BADGERYou know, when we put them in, drivers get upset with us. So this is a conversation particularly around infrastructure that we need to be having a lot more.

PAGEWell Robert, you said that you ride your bike to the metro station every day when you go to work. What have your experiences been?

PUENTESI don't want to overemphasize how long that trip is. It's actually pretty short, and it's on a dedicated bike path. It's an old railroad line that they've converted into a dedicated bike lane. It's a very easy, very convenient trip for me, and I think that's the case is that people will take whatever is the most convenient, the most reliable and the most -- the most predictable way they can get to work. It's really easy for me.

PUENTESBut we've conservative estimated that about half of America's population lives in places with land use regimes that haven't been revised for decades, and they're typically lower densities that restrict things like affordable housing and everything else but a single-family, detached home. So in these place, Emily was saying, it's not just the infrastructure on the street but the infrastructure of these communities and these neighborhoods, these cities.

PUENTESIf it's taking you a long, long time to get from one place to another, a bicycle might be a good solution for you, but in many ways, the car, as a sin as it might be for the caller, is a way to provide access to opportunity for lots and lots of different people. So, you know, where it's convenient folks are going to -- I don't think that folks have this modal splits in their head, well, the cars are evil or this is evil or this.

PUENTESThey're going to do whatever they have to do to get what they have to get done. In a place like Manhattan, where I am right now, it's very difficult to take a car around because it's very congested, it's very expensive. In a place like Roanoke or Fayetteville, where the callers are coming from, it might be a lot easier to take a car in those cases.

PAGEPeter?

NEWMANYeah, the history of cities is such that convenience is absolutely what drives the structure of them. And the old walking cities you could walk across and were only a few kilometers long, but that was because the travel time budget that has been the case for all human history, really, is about an hour a day. And so you couldn't walk that far. And then trams and trains came and spread the cities out, and cars even further. But they all still have roughly an hour a day, on average, the travel time budget. If you go beyond that, people start getting very angry.

NEWMANSo to expect people to ride in very long, 60-kilometer, 60 miles of a bike lane is not going to happen because it's going to take too long. You do -- bikes work well in central areas, in walkable areas and a little bit beyond that, out into the old tram areas. So Copenhagen is so high in bicycle use because it's people going where the old trams used to go. And so it is about the fabric of the cities as much as anything. It's not just that we, as Robert says, have a modal split in our heads, we find what's most convenient, and we live in an area that enables that convenience.

PUENTESWhat we're saying in this book is let's make more of that fabric that is more transit-oriented, more walkable, more cycleable, because that's where the demand is.

PAGELet's go to Joe, he's calling us from Aberdeen, North Carolina. Joe, thanks for joining us on the Diane Rehm Show.

JOEYeah, thanks for having me.

PAGEYes, go ahead, you have a comment or a question?

JOEYeah actually a two-part question. First of all, there's been a large push lately for electric cars and also self-driven electric cars, and how -- what would be the difference in just focusing on transitioning all the cars to electric and self-driven cars, which would eliminate a lot of the safety issues and also environmental concerns? And then the second part is, how do we take into account for the United States and its diversity in terms of climate, where some cities it's impossible to walk even to the bus stop in the winter, and also in other cities, it's impossible to walk to the bus stop in the summer for 105 degree temperature. Just a quick question, and I'll listen to it offline.

PAGEAnd Joe, let me ask you, how do you get to work? How do you -- what kind of transportation do you use?

JOEWell, I'm an insurance agent, so I drive everywhere.

PAGEAnd do you...

JOEAnd I also, I work an hour and a half away, in Greensboro. So when I go to the office, I drive.

PAGEYeah, and do you like driving, or would you rather not have to drive so much?

JOEOh, I would love to not have to drive so much, yeah, that would be great. It's expensive, and I put a lot of miles on my car in a year, so...

PAGEJoe, thanks so much for your call. Let's go to the -- for your call. Let's talk first about self-driving cars, electric cars. What kind of impact is that going to have, do you think, Peter Newman?

NEWMANWell, I think there's a lot of hype around them. The -- they're not going to be as significant in our cities as some of that hype. The electric vehicles certainly are coming, and they will be very important, and hopefully Joe will drive around in one of them and be less polluting because of that. But an autonomous vehicle, maybe he'll be driven around by one all day, but I doubt it, and the reality is that the -- if you have electric, autonomous vehicles in a city, they are still cars, and they are taking up too much space in certain parts of the city.

NEWMANSo central cities will not be good places for electric autonomous vehicles. They will still be just as inefficient, causing too many problems of -- that actually are harming the walkability of an area. That walkability is -- the key to that is that that's the new economy, the new competition. So the people, cities, oriented factor that is drawing capital now is still going to be a problem if you have electric autonomous vehicles.

NEWMANSo we do need to think about where these vehicles are going to be as much as what kind of fuel they're using, and they don't belong in many parts of cities.

PAGEEmily, I know this is a subject you've written about.

BADGERYeah, I mean, I think that self-driving cars raise all of these fascinating implications for cities that could go in any number of wildly different directions. So, you know, there's one prediction for the future that says that, you know, a world where there's a fleet of self-driving cars driving around everywhere, then, you know, you just call one up, and it will come and pick you up, take you where you need to do, drop you off, no one needs to own a car anymore.

BADGERAnd if no one owns a car anymore, then we don't need big parking garages in downtowns, and we don't need to design housing that has parking garages in it, and, you know, we're not going to have the same kind of traffic of people circling around the block looking for ways to part. And this is a very sort of optimistic view of what self-driving cars could do.

BADGERBut on the other hand, a very pessimistic view is that, you know, self-driving cars could potentially enable people to live even farther away than they already do. I mean, if getting to work every day means sitting in the back seat of a car that's driven to work for you by a machine, you know, you can read your morning paper, you can drink your coffee, it can be a productive time for you. So, you know, potentially it could make sprawl even worse.

BADGERSo these are like two diametrically opposed visions of what they could do for cities, and I think it's completely unclear, you know, where we're going to wind up in the middle, but I think these are fascinating questions.

PAGERobert, what's the future of these self-driving cars? Are we looking at something that is really going to be a formidable trend in the near-term future?

PUENTESI think a lot of folks do believe that it's coming. I think Peter's right that there's a lot of hype around it. I don't think it's coming as fast as people think it is. We know it's being tested in places all across the country. So it's on its way. I think Emily, though, is exactly right that it's -- we don't exact -- no one can tell you what the future is going to look like with these things. Does it mean that we're going to be sprawling out farther? If some -- if these cars are taking folks downtown, and they drop you at work, well, what are they doing during the day? Are they just driving around? Is that more cars?

PUENTESSo I think we don't really have a good sense of what the future means, but I think it's also important to look at what kind of vehicles and how can we take that technology, which is so focused on the self-driving cars, can we do things like bus platooning much better, have buses running at really close connections between them so that you're moving them much more fast down a high-capacity corridor? What can you do around trucking, for example? Can you move goods in places like Detroit, you know, these heavy, heavy trading corridors much better?

PUENTESSo I don't have any doubt that the technology is coming. I think that our challenges are going to be institutional. But I think we're going to test it out more on some of these public transit vehicles and trucks before we see them driving around people day to day.

PAGEI'm Susan Page, and you're listening to the Diane Rehm Show. We've been taking your calls. Let's go to Ray, calling us from Delaplane, Virginia. Hi Ray, you're on the air.

RAYThank you. Yes, so I believe that while I appreciate what the sustainability people are trying to do, I think they are wrong because they have grossly underestimated the cost both to the public and to individuals. So my story, my first -- my first home I bought was within a mile of my first job, and that was a real luxury, but later the job moved 25 miles out into the suburbs, and so I was driving the wrong direction for a while and eventually move to a farm -- moved to a farm that's even farther out, so now I was driving on the inbound side about the same distance, so about 25 miles.

RAYBut on the farm I have two hybrids and four trucks. So I have a lot of vehicles. The hybrids have now accumulated so many miles that their cost is down around 20 cents a mile, which is about one-fifth of what it costs for one passenger mile on the county bus service.

PAGEWell that's quite a savings, Ray. Thanks so much for your call. You know, that -- we've got an emailer, Joseph in Bethesda, Maryland, who has written about another factor that people consider. He writes, my wife and I lived in D.C. for many years with no car, using bus, metro and bikes to commute around the city and flex car services when we needed to. Then we had a daughter. A car was suddenly a must. With that car we then could consider a more affordable suburban home purchase, but the car came first, then the burbs. Emily, this is a story you've heard before.

BADGERYeah, I mean, this comes back to what we were talking about earlier about how millennials are sort of at the leading edge of this trend of not being as dependent on cars. And, you know, we -- we haven't seen yet what's going to happen when a lot of millennials reach the stage of life where they want to buy homes, and they're having children, and their lives fundamentally change. And I think that, you know, it's absolutely true that it's -- you know, it's very easy for those of us who don't have children, who consider ourselves urbanists, who like to ride bikes everywhere, you know, to talk about how feasible it is to live your life without a car.

BADGERBut, you know, it's the case for many people who have children that, you know, you can't necessarily call an Uber to take you somewhere if it's not going to have a child seat in the back, or you do this very complicated trip-chaining throughout your life, where, you know, on your way to work you drop your child off at daycare, and then on your way back you pick up the groceries, and you need to have the, you know, the storage in the back in order to put your groceries, or you keep the snacks in your that you want to feed your kid.

BADGERAnd, you know, for a lot of people what we're talking about is not going to make complete sense, and I think that's totally fine that, you know, not relying on a car is not going to work for everybody, but it's absolutely the case that, you know, thinking about families in particular, because families make up a huge share of, you know, the demographic that we're talking about, you know, they're going to have different needs, and this picture is going to look different for them.

PAGEWe had seen this huge rise of ride-sharing services and flex car services. What kind of impact have they had on this whole debate, Peter?

NEWMANYeah, smart systems are coming into transport so that we can do this ride-sharing, and Ubers can fit to help us with the last mile or the first mile. We can use public transport more effectively because we understand when it's going to be there and how often we can depend on it. So the idea that we could live without a car is easier now that we have smartphones that can link us into other options.

PAGEOf course it means we live without owning a car. It doesn't mean we live without using a car.

NEWMANWell there's certainly cars in most of those trip systems, usually at the top end or the bottom end of a long trip, but the -- having the option of a fast rail connection between those, last mile and first mile, that's the key thing because increasingly the public transport systems are faster than the traffic. That's why we're getting this (word?). That's why the millennials are choosing to come into areas where they don't have to drive as much because you're not saving time anymore by having a car. You're actually losing time.

NEWMANSo you've got to get out of the rut of heavy car dependence because it is no longer working for you, and that's why we need to change our cities to make more of the -- available for people who cannot have to have a car.

PAGEPeter Newman, he's author of "The End of Automobile Dependence: How Cities are Moving Beyond Car-Based Planning." And we've also been joined this hour by Robert Puentes, president and CEO of the Eno Center for Transportation, and Emily Badger, a reporter covering urban policy for The Washington Post Wonkblog. Thank you all for joining us this hour on "The Diane Rehm Show." I'm Susan...

BADGERThanks so much.

PAGEI'm Susan Page of USA Today, sitting in for Diane Rehm. Thanks for listening.