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Episode 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’re 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: 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.


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

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

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