Rebutting the “Empty Bus” Argument Against Transit

From Jarrett Walker over at Human Transit comes some very useful ammunition in the battle of reasonable people against knee-jerk transit-bashers.

Walker begins his post by quoting from a story in Canada’s National Post headlined "Save the Environment: Don’t Take Transit." The article posits that because many buses run empty for much of the day, they are environmentally inferior to private automobiles. Anti-transit stalwarts Wendell Cox and Randal O’Toole are cited in support of this argument. (Ignored is the research that shows how dramatically even a 10 percent increase in US transit ridership could reduce CO2 emissions.)

Human Transit’s Walker says that transit advocates can’t afford to ignore this line of thinking, infuriating though that may be, and he offers his rebuttal. It’s worth reading in full, but here’s a sample:

346594696_364f16e0d6.jpgPhoto: lantzilla via Flickr

almost 20 years as a transit planning consultant, I’ve looked closely
the operations of at least 100 bus and bus+rail systems on three
continents, and I have never encountered one whose supreme and
overriding goal was to maximize its ridership.  All transit agencies
would like more people to ride, but they are required to run many, many
empty buses for reasons unrelated to ridership or environmental goals. To describe the resulting empty buses as a failure of transit, as Cox
does, is simply a false description of transit’s real objectives.…

[I]n the real world, transit agencies have
to balance contradictory demands to (a) maximize ridership and (b)
provide a little bit of service everywhere regardless of ridership,
both to meet demands for "equity" and to serve the needs of
transit-dependent persons.

One analysis that I’ve done for
several transit agencies is to sort the services according to whether
they serve a "ridership" related purpose or a "coverage" related
purpose.  Ridership services are justified by how many people ride them.  Coverage services
are justified by how badly people need them, or because certain suburbs
feel they deserve them, but not based on how many people ride.  I
encourage transit agencies to identify which are which.  Once a transit
agency can identify which of its services are trying to
maximize ridership, you can fairly judge how well those services are
doing in meeting that objective, including all the environmental
benefits that follow.  Until then, the Cox argument is smoke and

More from around the network: Bike Friendly Oak Cliff reports on misguided municipal efforts to stifle the Dallas neighborhood’s burgeoning street culture. Tucson Bike Lawyer says that city is gearing up for its own ciclovía. And The WashCycle has the scoop on the University of Maryland’s efforts to increase campus bike ridership.

  • garyg

    (Ignored is the research that shows how dramatically even a 10 percent increase in US transit ridership could reduce CO2 emissions.)

    Sorry, but this claim (citing “research” consisting of a report by a political lobbying organization) is just total nonsense. First, an increase in transit ridership would not reduce CO2 emissions at all. What you mean to argue is that the SUBSTITUTION of transit for current travel by car equal to 10% of current transit use would dramatically reduce emissions. The emissions reduction would come from the allegedly greater energy efficiency of transit vs cars. In fact, transit overall is not more energy efficient than car travel, or is only slightly more efficient. But we do not need to do any calculations regarding energy efficiency to see that this substitution of transit for cars could not possibly produce a “dramatic” reduction in CO2 emissions. The governing fact is the ratio of current travel by car to current travel by transit. Transit provides less than 2% of all passsenger-miles of motorized surface transportation. A substitution from cars to transit equal to 10% of current transit use would reduce car travel by just A FEW TENTHS OF A PERCENT. The effect on carbon emissions would be negligible.

  • egk

    The 10% annual increase that is mentioned in the study translates into a doubling in transit ridership in 7 years or so. More importantly, since transit users on average consume less transportation (about half that of a car-driver) drivers who shifts to transit will, over the long haul reduce the total number of passenger miles traveled.

    If you do that math you’ll find that a 10% increase in transit use annually for about a decade results in something like a 10% reduction in emissions. This is a level of reduction that engineers working very hard (not here – in Europe) have been unable to achieve in the last 20 years for cars. Not negligible.

  • gargy


    A 10% annual increase in transit use for 7 years is a total fantasy. The last time transit use grew by 10% in a single year was 1943! It has NEVER had a 10% annual increase for more than two consecutive years since APTA historical records began (the year 1902). It did increase by about 10% over the 8-year period from 2000 and 2008, but much of that increase was due to population growth, not mode-switching from cars, and it has since fallen again. The most recent ridership report from APTA shows a year-to-date decline in unlinked transit trips of about 2.6%.

    To reduce his total passenger-miles by half, a car user would need not merely to substitute transit use for car use, but dramatically change his lifestyle. And since transit is such a tiny part of our transportation system, and cars so overwhelmingly dominant, there is just no remotely plausible scenario under which mode-switching from cars to transit could reduce carbon emissions by more than a token amount on a timescale shorter than many, many decades.

  • egk

    Decades is the timescale when transportation planning is at issue. Of course a 10% annual increase in transit ridership increase – sustained over decades – is an ambitious goal. But denying that such growth would result in significant carbon reductions is disingenuous. It would. Precisely because the USA has such unnaturally high levels of automobile usage are the oportunities for reducing carbon emissions by reducing driving so good. It would be much harder to get 10% annual transit growth in European or Asian countries where transit use is already high. (And to come back to the main point: much of the reason that Europeans and Asians (and New Yorkers) polute so much less than the average American is that they need to travel less far on a day to day basis. The land use patterns that come with increased transit use reduce total travel. Even when cars remain dominant: Driving accounts for about 80% of the passenger miles in Germany. Yet German per capita carbon emissions are only half that of Americans.)

  • garyg

    Decades is the timescale when transportation planning is at issue.

    The point is that under any remotely plausible scenario mode-shifting from cars to transit would yield only trivial reductions in carbon emissions even on a timescale of decades. The only plausible way of achieving large-scale reductions in carbon emissions from our surface transportation system within 30 or 40 years is through cleaner cars.

    Of course a 10% annual increase in transit ridership increase – sustained over decades – is an ambitious goal.

    It’s not ambitious. It’s unprecedented. It’s inconceivable. Nothing remotely like it has happened in the 107 years of transit ridership recorded in APTA’s archives. As I said, the last year that transit grew by 10% in a single year was 1943. And it has never grown by 10% for more than two consecutive years.


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