Some of the major environmental impact of transport development are:
The growth of speedy transportation is man’s greatest achievement in minimising distances but at the same time it has also become a cause of environmental degradation. Concern over the environmental consequences of transport development is long-standing. The environmental implications of transport development have become very widely recognised with a plethora of local, national and international, governmental and non-governmental organisations contributing to the debate by producing their own policy prescriptions and agendas for action.
In considering the relationship between transport and the environment we are immediately confronted with a potential paradox: on the one hand, modern industrial societies pursue economic growth through the open exchange of people, raw materials, energy, goods and services in an increasingly global marketplace, yet, on the other, the transport systems required to allow such exchange may be exerting pressures on the environment that degrade the functional integrity and quality of natural ecosystems to the extent that the prospect of maintaining or achieving a high quality of life in many human societies is threatened. In short, we cannot live without transport development, but neither may we be able to cope with its side-effects over the long term.
The European Union’s Fifth Environmental Action Programme states that transport is “vital to the distribution of goods and services, and to trade and to regional development”, but argues that current trends towards increasing transport demand are likely to result in “greater inefficiency, congestion, pollution, wastage of time and value, danger to life and general economic loss” (Commission of the European Communities, 1992:6). This article examines some of the major environmental impacts of transport development.
1. Energy Consumption in Transport and Environmental Pollution:
Transport requires energy mainly for vehicle operation and to some extent also for manufacturing of the vehicle. Figure 7.1 depicts the transport energy system and pollution.
The energy consumption in transport sector is the main cause of pollution. There are significant differences in fuel efficiencies between various modes of transport, for example, consumption of energy in cars is more among urban transport modes. Although there has been a significant improvement in the fuel efficiency in cars and other automobiles. It is estimated that in developed countries like UK. The traffic increases up to 142 per cent predicted for the year 2025, the energy consumption will continue to increase substantially, in spite of fuel efficiency measures.
2. Air Pollution:
Transport is a major source of air pollution not only in developed but in developing countries also. Ecologists believe that the rapid increase in the number of vehicles on our roads, which has taken place without any real restriction, is fast developing into an environmental crisis. Exhaust fumes are the major source of atmospheric pollution by the motor vehicle.
The main pollutants are outlined below:
(i) Carbon monoxide (CO):
This is a poisonous gas caused as a result of incomplete combustion;
(ii) Un-burnt hydrocarbons (HC):
This is caused by the evaporation of petrol and the discharge of only partially burnt hydrocarbons;
(iii) Other gases and deposits:
Nitrogen oxides, tetraethyl lead and carbon dust particles;
Organic compounds containing the group CHO in their structures. The average quantity of pollutants emitted by petrol and diesel driven vehicles is depicted in Table 7.1.
It is clear that very large amount of pollutants are being emitted from various forms of transport into the air that we breathe. These emissions are also responsible for the increase in ‘global warming’. The most obvious way of achieving a reduction in pollution by motor vehicles is to reduce the emission of fumes at source. A short-term solution is likely to be made by medications to the present type of engine and to improve combustion within the exhaust system, as Japanese manufactures have done in many cases.
3. Noise Pollution:
Another side’ effect of transport systems is the noise pollution. It is estimated that some 135 million people in OECD countries suffer transport noise levels in excess of 65 db. Figure 7.2 shows the noise levels from different sources including transportation.
The sources of noise from road vehicles are many and varied, including break squeal, door slam, loose loads, horns, over-amplified music systems, etc. Rail noise depends on the form of propulsion, the nature and load, the speed of train and the type of track. The noise pollution problems around airports are well known.
4. Land Consumption and Landscape Damage:
The provision of land-based transport requires the direct utilisation of land. Long strips of land are consumed, and large areas effectively divided into smaller ones (severance). Previous land uses, such as forestry, agriculture, housing and nature reserves, may be displaced, and zones adjacent to the new development rendered unsuitable for wide range of activities.
The latter aspect is true of pipelines carrying volatile materials (such as pressurised gas), for example, where a corridor of land along the route must be kept undeveloped for safety reason, even if the pipeline itself causes no direct consumption of land. Ironically, severance may seriously restrict the movement of people and animals between previously contiguous areas, with consequences for the quality of community life and the functional integrity of ecosystems.
Airports are such large blocks of land that they create severance effects in their particular location. Some severance effects, notably those of non-motorway type roads, are only partial, though increasing traffic density and speed increases the danger of pedestrian crossings on the same level. Traffic engineers have introduced more light-controlled crossings in recognition of this problem.
The use of road tunnels or viaducts can reduce severance, especially in urban areas, though the latter introduce significant visual impact, and both solutions are costly. Land consumption is not just a direct consequence of transport development; it may also occur indirectly as land is utilised for the extraction of the raw materials (principally aggregate) required for construction. An average of 76,000 tonnes of aggregate is required per kilometre of road lane, and approximately 90 million tonnes of aggregates are used in the UK every year in the construction and repair of roads (Royal Commission on Environmental Pollution, 1994).
Major impact of transport-related land loss and land use change may be a decline in the visual amenity or aesthetic attraction of the landscape. Visual impact may be essentially linear in nature for road, rail and inland waterway developments, or nodal in character as with the large terminal installations of sea and airports. Information on the scale of transport related landscape damage and loss of visual amenity is not widely available, partly due to the difficulties of assessing existing landscape quality. Obviously, however, the impact of adverse landscape change is likely to be much more significant in areas of high scenic value, such as national parks and mountain passes, or where a flat topography allows visual intrusion over a wide area.
5. Ecological Degradation:
The degradation of terrestrial and aquatic ecosystems, as measured by indicators such as reduced habitat/species diversity, primary productivity or the areal extent of ecologically valuable plant and animal communities, provides one of the most emotive aspects of the tension between transport development and environmental quality.
Severance is another direct consequence of land-based transport development. The physical division of natural or semi-natural ecosystems may inhibit the movement of animal and plant species across transport lines, and the associated reduction in size can threaten the viability and/or biodiversity of the smaller remnants. Likewise, the death of individual animals through collision with vehicles will be an all-too- familiar direct consequence of road transport for many readers. A recent report by Scottish Natural Heritage (1994) included a study, which put the annual road-kill loss of breeding amphibians in Scotland at 20-40 per cent, with an annual kill of barn owls of at least 3,000 individuals.
However, the indirect or secondary effects of transport development may also be responsible for many adverse impacts on wildlife, including those associated with air, water and noise pollution (described below). With reference to water pollution, for example, one could point to the ecological destruction associated with catastrophic, and internationally reported, oil leaks from stricken tanks or the contamination of coastal ecosystems. In brief, transport systems have had environmental effects. The effects of the various transport modes have been discussed. Table 7.2 indicates main environmental effects of transport.