64 Finance and economics The EconomistJanuary 20th 2018
T
HE most distractingly unrealistic feature of most science fic-
tion—by some margin—is how the great soaring cities of the
future never seem to struggle with traffic. Whatever dystopias lie
ahead, futuristsseem confident we can sort out congestion. If
hope that technologywill fix traffic springs eternal, history sug-
gests something different. Transport innovation, from railways to
cars, reshaped cities and drove economic advance. But it also
brought crowded commutes. Now, as tech firms and carmakers
aim to roll out fleets of driverless cars, it is worth asking: might
this time be different? Alas, artificial intelligence (AI) is unlikely to
succeed where steel rails and internal-combustion engines failed.
More’s the pity. In America alone, traffic congestion brings
economic losses estimated in the hundredsof billions of dollars
each year. Such costswill rise unless existing transport systems
receive badly needed investment. For example, fixing New York’s
beleaguered, overcrowded subway will take at least $100bn, ac-
cording to one recent estimate. A driverlessdeus ex machina
might seem to spare governments some difficult decisions.
But congestion is a near-inevitable side-effect of urban
growth. Cities exist because being near to other people brings
enormous advantages. Proximity allows people to find friends,
mates and business partners, to discuss ideas and generate new
ones, and to trade (and so to capture the benefits of specialisa-
tion). Regrettably, clumping leads to crowding: the more people
an area houses, the greater the competition for its scarce re-
sources, from seats at a hot new restaurant to space on public
roadways. Each new arrival enhances a city’smagic but also adds
to congestion. Cities growuntil costsoutstrip benefits.
New transport technologies are not useless. Mass-transit rail-
ways and highways allowed big cities to getbigger. But their con-
gestion-easing benefits inevitably proved temporary. When the
New York subway extended into northern Manhattan, it became
practical to live far from the dirty, expensive, crowded downtown
area, while still enjoying access to the city’s social and economic
benefits. So the city’s population rose—a lot—leaving New York-
ers once more cheek by jowl. A post-war highway-building boom
in America yielded explosive growth in citysuburbs. Cities once
again found their equilibrium, however, asthe suburban land-
rush led to road congestion, raising the cost of living far from em-ployment centres. In a paperpublished in 2011, Gilles Duranton,
of the University of Pennsylvania, and Matthew Turner, of
Brown University, identified a “fundamental law of road conges-
tion”: namely, that building more highways does not alleviate
congestion. Rather, it attractsmore residents, leads to more driv-
ing by existing residents and boosts transport-intensive eco-
nomic activity, until roads are once again crammed.
Driverless cars should cut traffic, other things being equal.
Lower accident rateswill mean fewer crash-related hold-ups,
while AIs that can pilot cars more closely together will boost road
capacity. But reductions in traffic will make living in currently
congested areas more attractive and hence more populous. Miles
travelled per person might also rise, since self-driving technology
frees passengers to use travel time for work or sleep. And just as
new highways prompt a rise in transport-intensive business, driv-
erless vehicles could generate lots of new road-using activity.
Where now a worker might pop into the coffee shop before going
to work, for example, a latte might soon be delivered in a driver-
less vehicle. The technology of driverless cars may make us safer
and more productive, but not necessarily less traffic-bound.
It might, however, improve traffic by making it easier, political-
ly, to impose tolls on roads. Jams occur because a scarce resource,
the road, is underpriced, so more people drive than it can accom-
modate. But tolls could favour use of the roadway by those who
value it most. Some places already use such charges—London and
Singapore are examples—but they are rarely popular. Some driv-
ers balk at paying for what they once got for nothing, and others
are uneasy about the tracking of private vehicles that efficient
pricing requires. People seem notto objectto paying by the mile
when they are bring driven—by taxis and services like Uber and
Lyft—and the driverless programmes now being tested by
Waymo and GMfollow this model. If a driverless world is one in
which people generally buy rides rather than cars, then not only
might fewer unnecessary journeys be made, but also political re-
sistance to road-pricing could ease, and congestion with it.Ok, commuter
That might lead to a differentkind of dystopia (also with histori-
cal antecedents): one in which fast, functional transport is avail-
able only to those who can pay. Luckily, history also suggests a
solution: mass transit. Ride-hailingservices might introduce
multi-passenger vehicles and split travel costs across riders (they
could call them “buses”). Or, as Daniel Rauch and David Schlei-
cher of Yale University argue, governments might instead co-opt
the new transport ecosystem for their own purposes. They might
subsidise the travel of low-income workers, or take over such sys-
tems entirely (a common fate for mass-transit systems which be-
gin life as private enterprises, including the New York subway).
Municipal networks of driverless cars might prove less efficient
than private ones, particularly if cars are rationed on a first-come-
first-served basis ratherthan by price. But in the past city govern-
ments have felt that providing equal-opportunity access to cen-
tres of economic activity was worth the cost.
Should congestion prove ineradicable in a driverless world,
people will continue to hope for technological solutions, like the
long-promised flying cars. While we wait for that—and the clotted
skyways that would soon follow—governments would be wise
to keep their underground systems in good working order. 7Jam tomorrow
Driverless cars will not save cities from either traffic or infrastructure expenseFree exchange
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