TRANSPORT IMPACTS

Each stage of cultural development has been accompanied by technological[Page 1109]change which has demanded more numerous and sophisticated ways to transport goods and passengers. The period prior to the industrial revolution was characterised by basic transport means, such as foot, horseback and horse-drawn canal barges, with limited environmental damage. During the Industrial Revolution, however, rail transport became dominant in the industrialised countries. Steam trains had indirect impacts on the environment through a growing demand for metal and wood to construct tracks and direct impacts through pollution in the form of particulate emissions and gases.

Of even greater significance has been the emergence of terrestrial motor vehicles as the dominant form of transportation of both goods and passengers in the past few decades. This has led to road transport becoming a major source of air pollution. Indeed, in most industrialised countries, where the impacts are most intense, motor vehicles are responsible for around 5 per cent of total emissions of sulfur dioxide, 10 per cent of particulate emissions, 45 per cent of hydrocarbons, over 50 per cent of nitrogen oxides and about 80 per cent of carbon monoxide emissions. In addition, motor vehicles account for approximately one-quarter of worldwide anthropogenic carbon dioxide emissions, which is a significant contribution to global warming. Particulate matter emitted from vehicles is also of great concern due to the long residence time of dust particles in the atmosphere and their contribution to the formation of photochemical smog and dust veils. Moreover, road transport is the fastest-growing source of these pollutants, in line with the increase in car ownership worldwide and its associated impacts (e.g. traffic congestion and human health hazards associated with air pollution). Road-construction schemes have been unsuccessful in keeping pace with the increase in private-car ownership and road freight, especially in developing countries, where many urban areas are now hypercongested and very polluted.

Transportation by sea-going vessels is a source of marine pollution but this is, relatively, less of a problem than road transport. The transportation of oil in tankers has resulted in numerous oil spills, several of which have had disastrous impacts on the regional environment. The ecological impacts of such events are devastating in the short and long term as oil remains in the water column and bottom sediments for some time after the initial event. Air transport has received much less attention as a potential source of pollution but the release of gases and particles from aircraft engines does cause pollution in the higher levels of the atmosphere, as well as being a major source of noise pollution at ground level.

[See alsoair pollution, estuarine environments, transport policy]