One thing all global cities will have in common over the next several decades is rising traffic congestion. Moreover, that condition will have immense impacts upon the quality of life, not only in those cities, but over the whole globe. Since I am revising my book STUCK IN TRAFFIC, I am going to focus on this subject in my allotted ten minutes.

The world inventory of cars, trucks, and buses has been rising faster in percentage terms than the population of human beings in both developed and developing nations.

The total vehicle population just about doubled from 1980 to 2000, from 380 million to 752 million, a CAGR of 3.47%. From 1960 to 1980, the CAGR was 6.39%. The human population rose at a CAGR of 1.56% from 1980 to 2000, with a total gain of 1.623 billion, vs. the vehicle increase of 372 million.

In the world as a whole, the number of vehicles per 1,000 persons has risen from 36 in 1960 to 123 in 2000. The U.S. number is 778. If the world had one-half the ratio of the U.S., the total number of vehicles would be 2.4 billion instead of 752 million. It will be moving towards that level as developing nations get wealthier, if they do!

There is a strong worldwide desire of people of all types to own their own private means of mobility. It starts with bicycles, then moves to motorbikes, then to cars. This results from the superior mobility of all these means to the alternatives of walking or public transit. The share of movement by public transportation is falling throughout most of the world.

Because selling private vehicles is a profit-oriented business, it can proceed without regard to the availability of roads. As a result, vehicle ownership and use is growing much faster than road capacity throughout the world, even in the U.S. People buy vehicles in hope that they can enjoy more mobility, without having to pay for roads.

But roads and transit systems in most of the world are built by governments, which in most nations have incomes lagging behind overall private incomes. And most governments use some of the revenues generated by gasoline taxes for general purposes, not just transportation. So the total supply of road capacity to accommodate vehicles is rising much more slowly than the total inventory of vehicles. One outcome is pressure to finance new roads privately by using tolls to raise capital, mainly in the developing world.

The result is greatly increasing traffic congestion throughout the world, especially in developing countries, where the "gap" between rising vehicle ownership and new road production is greatest. Congestion is an inescapable part of large and growing regions

When a metropolitan area becomes really clogged by congestion, this puts pressure on the forms of development. Development is also influenced by the fact that large numbers of poor people in developing nations are moving into urban regions from rural areas. In all regions, people using all modes tend to travel about 1.0 to 1.5 hours per day.

Hence there is a premium on living near where you work, or working near where you live, to reduce commuting time. Yet most people need to be working during the same hours in order to maintain economic efficiency. In regions where a high fraction of jobs are in or near downtown, this creates pressure for people to live near there. So high-density housing is created near downtowns. But the prices of those units rise and cause their occupancy mainly by high-income households, as in London. So many of wealthy in developing nations live downtown or in near-downtown neighborhoods.

Lower-income households moving into such regions have to settle farther out, usually on vacant land where they can build their own shacks or barrios. But this creates a labor force that can be tapped by firms located far from downtowns. So there is also a pressure to decentralize employment away from the center towards outlying areas.

This decentralizing pressure is increased by the difficulty of moving trucks into and out of central areas in highly congested regions.

Congestion is not basically a problem, but a solution to the real underlying problem – which is that too many people are trying to use the limited supply of road space during the same hours each day. There are only four possible ways to cope with this problem:

• We could build enough roads to accommodate all of those people simultaneously. But that would be too expensive and would turn the entire region into a giant concrete slab, which we would hate.
• We could charge people high tolls to enter the roads during those hours, as many economists have proposed. But that is politically unacceptable because most Americans would believe they would be prevented from using the best roads in rush hours – that is unfair to all but the wealthy.
• We could expand public transit – but that will not work in the U.S. because such a small percentage of commuting is by transit – under 5 percent.
• The only solution left is waiting in line to use the roads – that is, congestion. So that is the method we use because it is superior to all the other rationing schemes.

Congestion is really a balancing mechanism we use to enable us to pursue other goals we have besides reducing travel time – such as having a wide range of choices of where to live and work, all working during the same hours, and living in low-density settlements.

The desire to live close to where you work means that both high-wage and low-wage workers need to live near each other, because both types are needed in every major employment center. This means there is more spatial mixing of varied income groups in developing nations with high levels of congestion.

Such mixing may not occur at the neighborhood level, but it will occur at a smaller grain than in the U.S., where income groups are widely separated. This mixing pattern is increased by the habit of squatters without much money occupying vacant lands in all parts of a growing region, including public spaces.

In developing nations, incomes are so low that it will be a long time before a really high percentage of the people can afford cars. So they must continue to use public transit, or privatized forms of transit such as jitney cars and buses. But the mobility of such vehicles is impeded by rising traffic congestion. That puts pressure on governments to build subways or other off-road public transit forms, even though they are extremely expensive. In nations where jobs are still concentrated in central areas, these modes may be sensible, even though they are big money losers throughout the world.

Vehicles now cause 26% of the carbon dioxide emissions in the world, and that fraction will rise as more vehicles are built – and we are now building about 60 million per year. The best long-range means of coping with rising air pollution is shifting to fuel cells run by hydrogen. But that would require both great technical improvements and a radical change in the fuel distribution system throughout the world – one of the world's largest industries.

Altogether, rising traffic congestion is going to be one of the most important future traits of all global cities in all nations throughout the world. This will happen no matter what anti-congestion tactics are adopted because of rising populations and rising incomes in all those cities. So get used to driving in congestion. Get yourself an air conditioned car with a stereo radio, a tape deck, a CD player, a hands-free telephone, a fax machine, and a microwave oven, and commute with someone you really like. Learn to enjoy congestion.