Substitution of bus for car travel in urban Britain: an economic evaluation of bus and car exhaust emission and other costs

摘要

Car exhaust emissions cause serious air pollution problems in manyregions and, at a global level, con- tribute to climate change. Caruse is also an important factor in other problems including trafficcongestion, road accidents, noise pollution, community severance, andloss of countryside from road building. Forecasts of furtherincreases in car ownership and use have prompted calls forpolicy-makers to encourage car users to switch to other forms oftransport, particularly the bus. The effects of substituting bus forcar travel in urban areas are simulated by specifying a spreadsheetmodel incorporating two types of car (petrol and diesel engine) andthree types of bus (mini-, midi- and large bus). Six types of exhaustemission are considered for each vehicle type for the years l992,l995 and l999f carbon monoxide, volatile organic compounds, nitrogenoxides, sulphur dioxide, (small) particulate matter and carbondioxide. The paper provides a synthesis of monetary estimates ofthese exhaust emission and other costs. The other costs consideredare traffic congestion, fuel consumption, noise pollution, roadaccidents and road damage. The exhaust emission monetary costestimates, mainly from the United States and the United Kingdom, arediscussed within the context of a sensitivity analysis which allowsfor changes in parameters such as load factors, emission factors andthe individual exhaust emission cost estimates. The simulationresults show that substitution of bus for car travel generallydecreases the overall costs, particularly the costs of congestion,but increases exhaust emission costs if bus load factors areinsufficiently high. In order to reduce exhaust emission costs fromcar to bus transfer at given load factors, the most effective policyoption is to encourage the reduction of particulate emissions frombus engines. In terms of the overall costs, increasing bus loadfactors by relatively modest amounts can lead to substantialreductions in these overall costs. These results should be regardedas illustrative rather than definitive, given the uncertainties in anumber of parameter estimates and the need for further research inareas not covered by the paper.