Mass Transit Hysteria (Ep. 101)

(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 here.)

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.”

Mike B

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.


"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.


Gary Hewitt

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



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.

Chris V

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?


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.


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.

Joe J

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.


Glad to see someone is doing the numbers on this. Too many times it seems people vote for this stuff because it makes them feels good and they don’t see the money directly coming out of their pockets.

Mass transit should be employed where it makes sense, but as the above article pointed out, this isn’t everywhere.

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.

Currently much of the funding for mass transit does not come from the source of the true demand, the fare payers. Much of the cost of a ride is funded by tax payers. For a specific example, observe the breakdown of Sacramento California’s Regional Transit system:

Percentage of Operating Expenses Funded by:
Federal Assistance 15%
State Sales Taxes 29%
Local Sales Taxes 29%
Fare Receipts 21%
Other sources 6%



"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.


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.


RM Berkman

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.


Philo Pharynx

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.

Jack Jackson

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?


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.


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.


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?

Rideshare 2.0

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.