rail analysis must reflect reality
Since the incredible expansion of suburbs after World War
II, we have radically changed our means of getting to work. Not only getting
there, but also what we do on the way there — and on the way back. We take our
children to school, go for exercise, or go shopping and we no longer shop
Nor do we shop at the small local store, but in
supermarkets, and lately, the big box stores such as Costco, which are even
As we move from town to the distant suburbs we find that bus
service is now every hour instead of every few minutes, and so we use it less.
In addition, our time is more valuable than it used to be.
Accordingly, it plays a bigger role in the decision about how we commute.
It is not that we are in love with our automobiles; it is
that we value our time more.
These factors are the reasons why the percentage of
commuters using public transportation has declined both in Hawaii and on the Mainland every decade
since the U.S. Census began measuring it in 1960.
We must bear this is mind as the City undertakes the
Alternatives Analysis, which is to determine whether we go for rail or HOT
lanes, the high occupancy tollway option that gives priority to buses and
For each of these alternatives the city must forecast
transit ridership and effects on traffic congestion. However, potential errors
in forecasting ridership[i]
will be the single most important element of the formal Alternatives Analysis.
Earlier this year the prestigious American Planning
Association Journal published the results of a comprehensive worldwide study of
210 transportation infrastructure projects in 14 countries with total costs of
The study found that “for 9 out of 10
rail projects, passenger forecasts are overestimated; the average over
estimation is 106%.” They added, “Our
data also show that forecasts have not become more accurate over the 30-year
period studied, despite claims to the contrary by forecasters.”[iii]
analyzing the reasons for overestimating ridership they say, [iv]
“Forecasts here become part of the
political rhetoric aimed at showing voters that something is being done—or will
be done—about the problems at hand. In such cases it may be difficult for forecasters
and planners to argue for more realistic forecasts, because politicians may use
forecasts to show political intent, not the most likely outcome.”[v]
The city has projected ridership for their various past
transit projects and, at the same time, and using the same model, forecast for
what is called “no-build,” that being the anticipated ridership if the City was
to do nothing beyond already planned road improvements and merely expanded the
The HART rail plan,[vi]
the Hali 2000 study, and the 1992 rail study[vii]
all forecast bus ridership to be between 85 and 100 million annually. All
dramatically overestimated ridership, which today is less than 70 million.[viii]
The real significance is that since the city’s computer
models were grossly in error forecasting the “no-build” bus option, then the
same models would have produced similar errors in the rail transit forecasts
and are likely to do so again.
There have been two major defects in all of the City’s
earlier forecasts for new transit projects. First, has been the lack of
comparison with other metro areas that have already built rail, to review what
they have experienced and reconcile the differences between their actual
results and our forecast.
The second defect has been the lack of backcasting. That is,
using today’s computer models and the data from earlier studies to try to
forecast today’s actual ridership. If the City’s models cannot do it
accurately, they should seek ones that do.
As an example of the difficulties the city faces, consider
that of the five metropolitan areas that built rail between 1990 and 2000 -- Los Angeles, St. Louis, Denver, Dallas, and Salt Lake City – at the end of the period only one showed
an increase in the percentage of commuters using transit of any kind – Denver from 4.0 to 4.3
Even more discouraging for rail proponents is that these
five places experienced 860,000 new commuters driving to work while only 22,000
more commuters used transit resulting in a further decline in the percentage
using transit – and increased traffic congestion.
In short, if the city does not instruct the consultant to do
the Alternatives Analysis using comparables or backcasting, or some similar
safeguards, you will know it is “same old, same old.”
Cliff Slater is a regular columnist whose footnoted
columns are at www.lava.net
Kain, J. F. (1990). Deception in Dallas: Strategic
misrepresentation in rail transit promotion and evaluation. Journal of the
American Planning Association, 56(2), 184–196.
Wachs, M. (1989). When planners lie with numbers. Journal
of the American Planning Association, 55(4), 476–479.
Wachs, M. (1990). Ethics and advocacy in forecasting for
public policy. Business and Professional Ethics Journal, 9(1–2), 141–157.
Pickrell, D. H. (1990). Urban rail transit projects:
Forecast versus actual ridership and cost. Washington, DC:
U.S. Department of Transportation.
Pickrell, D. H. (1992). A desire named streetcar: Fantasy
and fact in rail transit planning. Journal of the American Planning Association,
“This article presents results from the first statistically significant study
of traffic forecasts in transportation infrastructure projects. The sample used
is the largest of its kind, covering 210
projects in 14 nations
worth U.S.$59 billion.
The study shows with very high statistical signifi- cance that forecasters
generally do a poor job of estimating the demand for transportation
infrastructure projects. For 9 out
of 10 rail projects,
passenger forecasts are overestimated; the average overestimation is 106%. For half of all road
projects, the difference between actual and forecasted traffic is more than ±20%. The result is substantial
financial risks, which are typically ignored or downplayed by planners and
decision makers to the detriment of social and economic welfare.
Our data also show that forecasts have not become more
accurate over the 30-year
period studied, despite claims to the contrary by forecasters. The causes of
inaccuracy in forecasts are different for rail and road projects, with
political causes playing a larger role for rail than for road. The cure is
transparency, accountability, and new forecasting methods. The challenge is to
change the governance structures for forecasting and project development.
Our article shows how planners may help achieve this.
Flyvbjerg is a professor of planning at Aalborg University, Denmark.
He is founder and director of the university’s research program on large-scale
infrastructure planning. His latest books are Megaprojects and Risk (Cambridge
University Press, 2003,
with Nils Bruzelius and Werner Rothengatter), Making Social Science Matter
(Cambridge University Press, 2001),
and Power (University of Chicago Press, 1998). Mette
K. Skamris Holm is a former assistant professor of planning at Aalborg University.
She now works as a planner with Aalborg Municipality.
Søren L. Buhl is an
associate professor of mathematics at Aalborg University.
He is associate statistician with the university’s research program on
large-scale infrastructure planning.”
Journal of the American Planning Association, Vol. 71, No. 2, Spring 2005.
This meshes perfectly with Winston Churchill’s adage that, “Political skill is
the ability of foretell what is going to happen tomorrow, next week, next month
and next year. And to have the ability afterwards to explain why it didn't
Transit Coalition for Honolulu.
The Hart Book. 1981.
1992 Final Environment Impact Statement. 4-10.7
The last time bus ridership was this low was in 1977 with 66.6 million riders
yet only 350 buses. Today, we have 525 buses, up 50 percent from 1977, yet
ridership is down from then.