Transport and the Environment

Transport and the environment

The chapter examines how transport affects the environment; how its impact can be quantified in economic terms; and how economic incentives can be used to reduce the environmental cost of transport, as well as addressing other externalities associated particularly with car use, such as congestion.

The environmental impacts of transport

“Transportation services are essential component of economic activity, and are one key to its growth. Transportation has a number of environmental side effects that people dislike. Through the emission of pollutants by cars, lorries, buses, trains, and airplanes; through land-take, for example for new airports and new roads and; increase in noise levels. Economics can help us to quantify how bad these side-effects are, and can also help us design for reducing them.”

Pollution emissions

“Emissions can be categorized into three broad types according to their effects. First, local pollutants. City traffic is a significant source of pollutants. Increase in those pollutants is linked to lower local air-quality and increase in illnesses. The second effect is regional. Acid rain has been blamed for water pollution and fish death. Transport is a major source of two of the constituents of acid rain. Finally transport is a significant net contributor to emissions of greenhouse gases.”

Land use

“Building roads and airports imposes environmental costs, these include: reductions in landscape quality; loss of wildlife habitat; islanding effects, whereby movement corridors for wildlife are disrupted; and loss of cultural heritage sites, such as when new roads are built over archaeological sites.”

Noise

“As traffic movements increase, so do noise levels. Noise impacts are usually measured as a weighted decibel, DbA, a scale which approximates the sensitivity of the human ear.”

Valuing the environmental impacts of transport

“Transport has the three main environmental impacts: on air quality, on noise, and as land-take. For local air pollution impacts, the dose-response relates increases in local concentrations of a given pollutant to increase in both illness and premature deaths.

For regional pollution impacts, such as acid rain, a variety of method could be used to estimate the cost of losses to fisheries and forest. Where market-valued crops are concerned, dose-response method can be used which relates the dose of increased deposition/acidity to changes in crop growth: these can be valued in money. For non-market values, such as ecosystem damage or damage to recreational fishing, methods such as contingent valuation and travel costs could be used. Finally, carbon dioxide emissions from transport may be costed in terms of their global warming potential using standards estimates of the value of tonne of carbon. Many transport investments involve land-take. For impacts on wildlife, cultural sites, and landscape, contingent valuation can and has been widely used as a valuation method. Finally for noise impact, the hedonic-pricing method can be used. This involves estimating a statistical relationship between ambient noise levels and house prices or rents.”

Cost-benefit analysis and transport.

“A major constituent of total benefits is often time savings. A bypass may reduce congestion in a town, and speed up the travel times of motorists traveling elsewhere. Time savings can be in terms of leisure time and working time. However we should note that time savings may be rather a temporary effect of the new road. Road investments are also motivated by a desire to reduce accident. Some roads schemes can reduce environmental damage: in the case of the bypass discussed here, noise levels in town many falls as traffic is diverted to the new road, whilst emissions in town may falls too if traffic speeds up. The benefits can be counted alongside the time savings and accidents reductions forecast. On the cost side, obvious elements include the cost of acquiring land, and the predicted cost of the labor and materials used inn road construction. Additional maintenance costs, net savings in maintenance costs in the town, also count. Cost benefit analysis can take into account most of the important impacts of a transport investment, and can test whether it represents an efficient use of public or private money.

 The population of gainers and losers may be quite different. Gainers included motorists passing through en route to elsewhere, and local residents now relieved of traffic congestion. Losers included all those who were