Urban road traffic congestion

Traffic jams now dominate life in the world's great cities. In Los Angeles drivers inch along 12-lane expressways. In Mexico City children start school late to avoid the morning smog. Bangkok's office-workers suffocate on packed buses for an average of 2 1/2 hours a day. All of this is caused by more people crowding into big cities but more importantly because people are moving more. Most of the extra moving is done in cars. Places like New York and London have nearly one-quarter of their land area devoted to roads and have vast metro systems under them and are near their capacity to do more for the driver.

During the rush hour traffic period in today's metropolises the breakdown of just one automobile for a 15-20 minute period can sometimes result in tens of thousands of people being late for work, sometimes by more than one hour. Transportation system breakdown slows traffic speeds. This in turn reduces the efficiency of fuel combustion in cars, which increases air pollution. The air pollution generated by inefficient transportation systems then reacts with other elements of the urban environment.

Traffic congestion results from thousands of unintegrated, linear, incremental responses to urban development pressures. To provide homes for citizens local governments often adopt a land use planning approach that permits one neighbourhood block to be built after another, each developed on a case-by-case basis with little overall integration of human activities such as residing, shopping, recreating and working. The roads that connect these neighbourhoods are also constructed without a long-term, integrated transportation concept. This kind of urban growth in many cities has resulted in urban sprawl, extreme dependency upon the private automobile to travel at all hours to places of residence, work, and recreation, as well as extreme traffic congestion.

In the UK in 1994 it was estimated that the cost of traffic jams was £15 billion a year, not to mention the number of deaths associated with automobile accidents during traffic jams. The cost of traffic jams in Belgium is $375,000,000 and 25 million hours a year. Vehicles wear out faster, petrol is consumed faster and accidents increase because of traffic jams. In Los Angeles, motorists who battle congestion are exposed to between two and four times the levels of cancer-causing toxic chemicals found elsewhere outdoors.