June 22, 1990
"Traffic Jams: A Tragedy of the Commons"
San Jose Mercury News
By Timothy Taylor
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NEXT time you're sitting in a long row of cars, contemplating
how "rush-hour traffic jam" is a contradiction in terms, think about
this: Traffic congestion is just a modern manifestation of a basic economic problem
that was causing congested grazing land way back in the Middle Ages.
In medieval Britain, although the grazing land was usually owned by a lord,
local commoners had a right to use that land for grazing their animals, fishing,
digging peat, and so on. This system often prospered for a time, at least by the
standards of seven or eight centuries ago. But as population increased, it always
ran into the same problem.
Any herdsman who decided to graze additional animals on the commons benefited
as an individual, while any costs of overgrazing were spread out and shared among
everyone who used the commons. From a private perspective, overgrazing made sense;
from a overall perspective, it injured the common resource on which everyone depended.
This well-known scenario was nicknamed "the tragedy of the commons"
by biology Professor Garrett Hardin in a 1968 article. He wrote, "As the
human population has increased, the commons has had to be abandoned in one aspect
after another. First we abandoned the commons in food gathering, enclosing farm
land and restricting pastures and hunting and fishing areas...
"Somewhat later we saw that the commons as a place for waste disposal
would also have to be abandoned. Restrictions on the disposal of domestic sewage
are widely accepted in the Western world; we are still struggling to close the
commons to pollution by automobiles, factories, insecticide sprayers, fertilizing
operations, and atomic energy installations."
If you harbor any doubt that the tragedy of the commons is still with us today,
try two experiments. First, offer ice cream to four or five little boys, but tell
them that they must eat it from a common bowl. If they pursue their individual
interests, as little boys tend to do, the common resource will be depleted much
more quickly than individual servings would have been.
The second experiment is to sit on a Bay Area highway during what is euphemistically
called the rush hour. Medieval herdsmen grazed too many animals on common fields;
today we put too many cars on the common roads. Each driver has made an individual
decision that he is better off waiting in traffic; from an overall view, the traffic
doesn't move and everyone is worse off.
When a commons is being overexploited -- whether it is grazing land or the
air around us or our roads -- the first response always seems to be a quasi-moral
appeal for all of us to voluntarily restrain ourselves and change our habits.
Here's what Garrett Hardin had to say about such appeals:
"If we ask a man who is exploiting a commons to desist 'in the name of
conscience,' what are we saying to him? What does he hear? Not only at the moment
but also in the wee small hours of the night when, half asleep, he remembers not
merely the words we used but also the non-verbal communication cues we gave him
"Sooner or later, consciously or subconsciously, he senses that he has
received two communications, and that they are contradictory: 1) (intended communication)
'If you don't do as we ask, we will openly condemn you for not acting like a responsible
citizen'; 2) (the unintended communication) 'If you do behave as we ask, we will
secretly condemn you for a simpleton who can be shamed into standing aside while
the rest of us exploit the commons."'
Maybe I'm more cynical than average, but I do hear that double message in the
advertising and enticements to carpool, vanpool, use public transit and so on.
It's the unmistakable sound of the majority holding back, waiting for the easily
guilt-ridden to step forward and make commuting easy for the rest of us.
Voluntary efforts or building new roads and mass transit systems can reduce
congestion a bit for a time, but the only lasting solution to traffic congestion
will be to stop treating the roads as a free commons during the rush hour.
I don't know what system will eventually replace the current method of allocating
space on the roads during rush hour, which is to make people wait in line. Maybe
it will be indirect incentives like toll roads; maybe laws that place direct limits
on who can drive during peak hours; maybe some social arrangement no one is even
But Bay Area drivers now spend 100 million hours a year sitting in traffic,
according to estimates cited by the Bay Area Economic Forum, and the delays are
rising. Multiply by the average Bay Area wage of $14 an hour, and it works out
to $1.4 billion of wasted time each year.
When traffic jams costing millions of dollars of lost time happen like clockwork
every working day, even a peasant from centuries before the invention of the automobile
could see what needs to change.
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