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. Mike B says:

    Remember that when the NYC Subway and other public transportation systems were built, many of them reached out into unpopulated areas where the “numbers” wouldn’t add up. The thing is that development followed transit and the same is generally true today, especially if proper land use policies are implemented. Transit is a chicken and egg problem, but because transit is most impractical after a highway centric transport model has been established and invested in it is better to err on the side of getting transit built as soon as possible.

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  2. James says:

    “And a bus burns an awful lot more fuel than a car!”

    Well, that sort of depends on the car, doesn’t it? Doing a quick search for bus mpg finds that as of 2010, buses averaged 7.2 mpg (from ) Now if your car happens to be the 2013 Cadillac Escalade ESV AWD, then per EPA figures you’ll be getting 14 mpg (city/highway). So it seems that a bus with two passengers beats an Escalade with one.

    Of course if (like me) you happen to drive a 1st gen Honda Insight that gets 70+ mpg, you need to have 10 passengers on the bus to match me (and 20 if I have a passenger). But there are a lot more Escalades than 1st gen Insights out there, which I suspect skews the figures in favor of the bus.

    We can take this a little further, too. When I lived in Switzerland, I noticed that most of the urban buses (and the trains) actually ran on electricity, drawn from overhead wires via a pantograph mechanism. Since much of Switzerland’s electricity comes from hydropower, there’s a nearly carbon-free mass transit system.

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  3. Gary Hewitt says:

    There are three ways that public transportation can reduce carbon emissions:

    1) Reducing Auto Trips: This is only variable considered in Mr. Morris’ blog post.

    2) Reducing Congestion: As the Onion article reflects, auto users know they benefit from reduced congestion when public transportation is available. The reduced idling and travel time for autos reduce emissions.

    3) Allowing for Compact Development: The existence of public transportation allows compact development where walking and biking are possible. Denser development allows people to live in Manhattan without a car and even allows people (such as Mr. Dubner) to be able to walk to work. These reduced trips also have a positive impact on emissions.

    The American Public Transportation Association has a more thoughtful way of calculating the Green House Gas Emissions for public transportation. It is available at

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    • Praxis says:

      But even the combined reduction from all three is tiny. According to studies cited by the Transportation Research Board, the reduction in CO2 emissions from the combined effects of mass transit on mode choice, congestion and compact development is about 0.5% of total emissions.

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    • Jim in Frankfort says:

      I live on forested acreage and I work at home 90% of the time … according to the implied offset calculation 1 acre of forested land consumes (offsets) 7 tons of CO2 emissions … so I have a net negative carbon footprint and I don’t live anywhere near a city.

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  4. Chris V says:

    I live in Honolulu, which has, no exaggeration, the worst traffic in the United States. The recent mayoral race became instead a referendum on the city’s plan to build a light rail system to alleviate some of the congestion. The anti-rail candidate’s plan was to implement more express buses, while the pro-rail candidate said that adding more vehicles to the already overcrowded highways would only make the situation worse. After months of vitriolic debates and ads for both sides, I would love to see an objective assessment of which plan is better. Maybe a new podcast on the topic?

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  5. Adam says:

    As a transportation planner, I would like to point out that this analysis does not take into account the cost of congestion. In many cases those 10 passengers per bus would translate into 10 more cars on the road. Many roads are at capacity during peak commuting hours, meaning that there is already bad congestion. Adding more cars would worsen congestion, resulting in a greater carbon footprint for everyone on the road. I would also like to point out that for many trips, bicycling is by far the most efficient form of transportation available. Sounds crazy to a lot of people, but take a hard look at your commute and try biking it. You may be pleasantly surprised.

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  6. keira says:

    This is a totally silly and disingenuous comparison. A bus carries an average of 10 people per trip in the average American city because most people are sticking to their cars and the bus service is probably pretty lousy. This is so obvious to be hardly worth pointing out except for your coy presentation of the issue.

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    • Joe J says:

      Bus service will always be lousy to some, because bus lines assume all are going to one location. By car one can go a straight route to destination, by bus it is based on the bus routes, which even if efficient for masses is often very inefficient for individuals. So a 5 mile drive with congestion taking half hour, becomes a 20 mile with 4 transfers 2 1/4 hour ordeal.

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  7. JAM says:

    Hidden due to low comment rating. Click here to see.

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    • Jeff says:

      “To accomplish this, we should probably look toward privatization so that the price signal could more clearly dictate where the best opportunities are for mass transit.”

      Only if we privatize the highways too. Tolls on every road and I’m on board.

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      • JAM says:

        With the exception of carbon pollution, your costs are much more internalized if you drive yourself than ride public transit.

        If you buy gasoline, you are paying federal and local fuel taxes which add up to about $0.50 per gallon. A large portion of this goes to road construction and maintenance. Therefore, you are paying a toll.

        Further, in most places you pay for pollution controls on your vehicle, required emissions testing, state licensing fees, and a higher fuel cost than would normally be the case for federally required reformulated fuels that burn cleaner. The big externality now is that this does not capture carbon pollution, but according to this article, public transit is doing worse than individual motorists in most places.

        However, as the mass transit systems are currently designed, as a rider, in most places you are externalizing your costs onto others as your fare does not come close to covering the costs.

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    • Malice in Wonderland says:

      Regarding % of operating expenses funded by…

      It really depends on the system. In Toronto for example, the rider pays about 70% of the operating cost via the fare, with the remaining 30% being funded by the municipal government through property taxes.

      There are no tolls on roads in Toronto. 100% of the road construction and maintenance cost is born via taxation by one of three levels of government (federal, provincial, municipal).

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  8. RM Berkman says:

    First of all, the use of the word “average” is meaningless, because it doesn’t indicate how that average was taken: was it taken from a single bus and then extrapolated, or was it taken from a fleet? Was it balanced to take into account the size of the population (as well as the size of the bus?) On some buses, 10 riders could be half full, which is not bad. Of course, if you’ve ridden on the crosstown M79 in NYC at 7:30 am, nobody would believe you.

    Perhaps the problem is that not enough people are using the bus on off hours – yes, there may only be a couple of people on a bus at 2 am, but don’t poor people need a way to travel? Maybe we could better use those buses if we charged half price between midnight and 5 am: you could double the number of riders, but it won’t cost double the cost to run it – the driver gets the same pay no matter how many people ride, and most of the power is used to move the bus anyway – adding another dozen or so people won’t raise the fuel costs all that much. In the end, you’ll collect the same revenue and fewer people will be in cars.

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    • Philo Pharynx says:

      A half-price bus doesn’t guarantee double the ridership. After all, amny people wouldn’t rider the bus during those late hours for safety reasons or because they aren’t out during those hours.

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