Mass Transit Hysteria: A New Marketplace Podcast

(Photo: Philip Matarese)

New York City’s subways and buses carry roughly seven million passengers a day, which goes a long way toward explaining why New Yorkers have one of the smallest carbon footprints in the U.S. Doesn’t that mean that mass transit is inevitably good for the environment?

Yes, no, and sometimes.

Our latest Freakonomics Radio on Marketplace podcast is called “Mass Transit Hysteria.” (You can download/subscribe at iTunes, get the RSS feed, listen via the media player above, or read the transcript below.) 

It’s based on a recent blog post by regular contributor Eric Morris and you’ll get to hear a good bit from Morris himself in the podcast. He does a great job explaining the nuts and bolts (and math) of the issue, and admirably teases out the complications that visit any conversation about transportation.

How to explain why mass transit is often embraced as an environmental panacea even when the numbers don’t add up? As the Onion once put it: “98 Percent of U.S. Commuters Favor Public Transportation for Others.”

Audio Transcript

Kai RYSSDAL: Time now for a little Freakonomics Radio -- it’s that moment every couple of weeks we talk to Stephen Dubner.  He is the co-author of the books and blog of the same name.  “The hidden side of everything” is what it’s all about. Dubner, how are you, man?


Stephen J. DUBNER: Doing well, Kai, thanks.  Here in New York, we are recovering still from Sandy.  The transit system has mostly recovered, our subways and buses are getting back to moving about 7 million passengers a day.


RYSSDAL: Which is honestly amazing.  The fact that they pumped out all that water is kind of crazy.


DUBNER: It is, and we’ve been doing it for years and years.  All that mass transit means that New Yorkers have one of the smallest per-capita carbon footprints in the entire United States.  Because we all know that mass transit is very, very good for the environment.  Correct?


RYSSDAL: We do know that.  The only thing we don’t know is where you’re going, Dubner.


DUBNER: I’m going to introduce you to Eric Morris.  He’s a regular contributor to and he’s a professor of urban planning at Clemson University:


Eric A. MORRIS: “Mass transit can be an incredible boon for the environment.  It can also not help the environment or maybe even hurt the environment.”


RYSSDAL: Make up your mind, man!  Come on.


DUBNER: How’s that for clarity?  Okay, let’s say we’re trying to figure out the energy efficiency of transporting one person -- Kai Ryssdal, let’s say -- in a car versus in a train or bus. Here’s Morris again:


MORRIS: “Obviously the energy expenditure in moving around a transit vehicle per passenger mile depends on the number of passengers.  Whether you have one passenger in a bus or 40 passengers in a bus, you’re going to be expending almost the same amount of energy.  So it all depends on the ridership and the occupancy that transit vehicles and, for that matter, autos carry.”


RYSSDAL: All right, so what do we know about occupancy and ridership?


DUBNER: Eric Morris tells us, the average American car carries 1.6 people – not many, of course, especially if you’re thinking about comparing it to mass transit. On the other hand, the average bus carries only 10 people. And a bus burns an awful lot more fuel than a car! Which led Morris to this rather surprising conclusion:


MORRIS: “Typically, moving a passenger a mile by bus requires roughly 20 percent more energy than moving a passenger around by car.  So, just in terms of energy expenditure, bus actually fares worse than car.”


RYSSDAL: That is crazy.  Also, this is the point in the broadcast where we’re going to start getting a lot of nasty letters because people are going to go, “wait!  How can that be?  I don’t understand!”


DUBNER: Don’t worry, we’re going to tick off other people in a moment.  Don’t worry about that.


RYSSDAL: Oh, good!


DUBNER:  Let me say this, though.  Trains are actually, on average, better than cars – more energy efficient per passenger.  Although that number is warped a little bit by one subway system -- the New York City subway, which is just a monster of size and efficiency.


RYSSDAL: So, let me just recap here because this is a little twisted. If I take the bus in an average American city, I’m hurting the environment more than if I just drive myself to work, and then trains are better than that, but not by a whole lot?


DUBNER: Well look, honestly, it’s not so simple. It’s very hard to come up with an answer to that specific question because of the tradeoffs here.  There’s time tradeoffs.  You’ve got to think about land use for parking.  Traffic fatalities that come with car travel that don’t come with train travel. But Eric Morris’s point is this: if you’re thinking about carbon footprints for moving people around, we’ve all caught a bit of what you might call “mass transit hysteria.”  We think that it’s the solution.  But it’s not necessarily. It’ll work great in a place like New York, but in other areas, you know we’ve picked a lot of the low-hanging fruit.  You try to put a new train system in a smaller city where people don’t have access to it -- Cleveland, Pittsburgh, Memphis, and those places – those train systems actually do worse than cars in terms of energy efficiency.  Here’s Eric Morris one more time.


MORRIS: “In general, pumping up ridership by constructing new transit systems or adding new transit service has to be looked at very skeptically.  On the other hand, if we can persuade more people to leave cars and move onto the existing transit service that we already have, that’s a complete win for the environment.”


RYSSDAL: “Persuading people to leave their cars” though.  That’s kind of interesting.


DUBNER: Yeah, it’s like the Onion once put it: “98 Percent of U.S. Commuters Favor Public Transportation for Others.”


RYSSDAL: Yeah.  But, if you’re this Clemson guy, Morris, how do you convince people to leave their cars?


DUBNER: Well, if you’re a liberal and you hate the idea that we are sort of discouraging certain kinds of mass transit, here’s an idea that you can hate if you’re a conservative: you get people to leave their cars by raising tolls on roads and taxes on gas and parking to incentivize more people to ride the transit systems that we’ve already spent billions on and are underused.


RYSSDAL: (Laughs)  Hey, before you go, let me ask you: what did you, take a cab today?  Ride the train down the studios?  What?


DUBNER: None of the above.  I’m in my office across the street from my apartment.


RYSSDAL: (Laughs)  Nice!


DUBNER: Nobody else’s carbon was killed in the making of this episode from my end.


RYSSDAL: Stephen Dubner. is the web site.  We’ll see you in a couple of weeks.


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  1. Jack Jackson says:

    How about the cost effectiveness of high speed rail for America. My vision is that much of the trucking traffic between our seaports, manufacturing centers, warehouses and urban centers should be via high speed rail. That is to expressly remove as much over the road truck traffic as possible. Final shipping would be by truck.

    How much high speed rail would it take to remove 50% of trucks? How about 80%? I presume some cities would have insufficient population to justify high speed access. How small is too small?

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  2. Kiran says:

    I live in the SF Bay area. If I ride BART from Fremont to Richmond I will have to pay $4.90. Instead if I go in my Toyota Prius car, I drive 40 miles. At the current gas price of $3.7 and 50 mpg for my car, I just need to spend $2.96. I shouldn’t include this but BART also charges $1 parking fee (for a round trip).

    So public transportation is no longer economical, not sure if it is greener.

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    • Lee says:

      Gas isn’t the only cost for a 40 mile trip in a car (mtce/ins/depreciation too); for most cars isn’t the standard amount 40 or 50 cents per mile?

      Besides, most (even in the Bay area) aren’t driving a Prius.

      I’m glad that you are, though.

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  3. James says:

    Taxes? That’s how you get people out of their cars and into mass transit? Taxes?

    I guess it wouldn’t do to figure out what is inconvenient about the current mass transit systems and improve them to make them /more/ convenient? Why can’t government see it’s job as to make their citizen’s lives better rather than figuring out how to make them act in ways they would rather not?

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  4. Rideshare 2.0 says:

    A sustainable mass transit solution for cities without proper subways or the funds to afford a rail infrastructure would be to crowdsource and build a collaborative vanpool network as the 10 passenger capacity is ideal.

    In addition, this solution is flexible as the routes are dynamic and aligns with the movement of employers and jobs.


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  5. Eliza says:

    If someone takes a train or bus to work, they will likely walk (or carpool) if they have other daily errands such as appointments, lunch or coffee. Carbon reduction from these “vehicle trips avoided” would be more difficult to calculate but should factor in.

    It would be great if you could get the data for individual who take transit, the average number of walk trips / transit trip for those who take transit at least once a day. This is different from the overall mode split (which often only accounts for commute trips). I guess to be fair you would have to compare it to the number of walk trips / car trips for drivers.

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  6. Mark J. Ambrose says:

    There is just one problem (and it is a fundamental one) with the argument presented. When one evaluates the costs and benefits of any decision, one doesn’t care about the resulting averages, one cares about the margins. This is one of the fundamental ideas of economics, so it is surprising that it was not addressed in an economics piece!

    So, if one considers expanding the bus system in a certain city, the comparison should NOT be the avg. C footprint of all bus riders in the city vs. the avg. C footprint of all who drive. It should be the avg. C footprint of all the new bus riders who switch to using transit because of the expanded system vs. the C footprint that they had driving their cars before switching to transit.

    Now the marginal values are harder to get at than the overall averages. To get them we have to know something about who is likely to switch to using transit. My guess is that the typical person who might switch to transit is more likely to have been commuting in a single occupant vehicle (simply because family units who combine trips probably will still do so and carpoolers as well). Similarly, we have to estimate the marginal C cost/passenger of the expanded system (somewhat easier to do using fuel and ridership numbers for the original and expanded system).

    Looking at things this way, all the low-hanging fruit may not be gone. There may still be a number of areas where expanding transit systems makes sense in terms of carbon footprints.

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