100 ■ CITIES AND CLIMATE CHANGE
In an increasing number of cities in low- or middle-income countries, the
dispersion of employment makes it inconvenient to use transit, because no transit
route goes directly to their location of employment. For those commuters who
cannot aff ord to use individual cars or motorcycles, the most convenient options
are collective taxis or minibuses. Commuting by microbuses at the expense of
transit has become the dominant transport mode in Gauteng, Mexico City, and
Tehran, for instance. As households’ income increases, the speed of transport
and convenience become more important factors than cost, or rather, higher-
income commuters give a higher value to the time spent commuting than do
lower-income ones. Speed of transport is limited in most transit system by fre-
quent stops and the time required for transfers. In city structures where a car is a
feasible alternative mode of transport, commuters who can aff ord the cost would
normally switch to individual cars.
Th e exhaustive study conducted by Pisarski (2006) on commuting char-
acteristics in U.S. cities gives an order of magnitude of the speed diff erence
between transit and individual cars in those cities (fi gure 4.3). Th e average
commuting distance is about the same between the diff erent modes except for
walking, cycling, and rail transport. One can see that in spite of the congestion
prevalent in most U.S. cities, commuting time by transit requires about double
the time required by individual cars. Travel time for car pooling when involving
Figure 4.3 Average Travel Time in U.S. Cities by Transport Mode
Source: Pisarski 2006.
Walk
Bike
Taxi
Motorcycle
Drive alone
Car 2 people
Car pool 3 people
Car pool 4 people
Minibus 5 or 6 people
Streetcar
Bus
Minibus 7+ people
Subway
Ferry
Railroad
12
19
20
22
24
27
31
34
39
44
46
47
48
66
71
0102030
Minutes40 50 60 70 80