1.6.1 Introduction
Transport, be it by road, rail, air, sea or inland waterway, is an indispensable component of modern society, providing for the rapid and easy movement of people and goods over distances. It gives an individual freedom and independence to travel, and it facilitates trade, returning enormous benefits to economies (1). However, transportation facilities incur major direct and indirect costs to society in terms of energy consumption, air pollution, noise, destruction of natural areas and habitats and global warming. Some of these costs are borne by individuals, but many of them accrue to society as a whole. It is imperative that urban transport systems become more sustainable and less destructive. Urban managers must lead the way in bringing about this change.

1.6.2 Trends in urban transport
Increasing prosperity has resulted in rising car ownership, and travel by car has increased in almost all countries at an enormous rate. This is even more evident in urban environments where trip length by car and public transport has been increasing as activities have become more dispersed. Suburb-to-suburb journeys have shown the fastest growth. At the same time, there has been a shift from walking and cycling to mechanised modes of transport. Greater car ownership has increased the public’s ability to travel anywhere at any time, and has enabled jobs, shops and services to relocate to peripheral areas. It has also allowed more people to enjoy living in spacious surroundings.

Over most of the past century, it was assumed that adequate transportation structures needed to be built since they provide an essential framework for growth and economic health. Accordingly, the main concern of transport planners and policy makers was in the "supply" of transportation, ensuring that the supporting infrastructure would be adequate to support all projected requirements. As a result, many analysts believe that most places have heavily overbuilt their physical transportation infrastructures, contributing to unsustainable levels of traffic and resource use (2,3).

Commerce and industry have taken advantage of the freedom offered by road movement. The ease with which goods can be transported has allowed innovations, such as “just-in-time” production and a reduction in warehousing facilities. Firms of all kinds have moved to sites at the edge of town so that they can exploit the increased mobility of car-owning customers and employees (2). However, all these changes that have been associated with economic growth have also brought undesirable effects or externalities. These effects range from traffic congestion and accidents to increased air and noise pollution, and even to such social effects as the isolation of people without access to a car. Emissions from transport are also associated with global warming.

1.6.3 Impacts of urban transport
Traffic-related air pollution is one of the most pressing problems in urban areas. In the majority of cities worldwide, road traffic is the predominant source of atmospheric emissions. Many air pollution studies have addressed issues at a global level, especially in relation to climate change, and at a regional level, with particular respect to trans-boundary delivery of acid rain from industrialized areas. However, it is increasingly recognised that population exposure to air pollutants is largely the result of city-generated air pollution. Human exposure to increased pollutant concentrations in densely populated urban areas is high (4). The impact on health of transport-related air pollution is among the leading concerns. Research in recent decades consistently indicates the adverse effects of outdoor air pollution on human health, and the evidence suggests that air pollution from transport is a significant factor. (5)

Transport is a major user of energy, and transport burns most of the world's petroleum. It contributes to a range of gaseous air pollutants and to suspended particulate matter (PM) of different sizes and composition. Hydrocarbon fuels produce carbon dioxide, a greenhouse gas widely thought to be the chief cause of global climate change, and petroleum-powered engines, especially inefficient ones, create air pollution. The term particulate matter describes a very diverse mixture of pollutants, consisting of particles suspended in the atmosphere. These cover a wide range of sizes and chemical characteristics. Most vehicles emit very fine particles of carbon (from Diesel engines), inorganic lead compounds (from petrol engines using leaded petrol) and other metals used in oils to enhance the performance of petrol engines. These particles also create dust, soil buildings and damage health (2). Tailpipe emissions of primary particles from road transport account for up to 30% of fine PM in urban areas (5). Other emissions from vehicles that are cause for concern include: carbon monoxide (CO), oxides of nitrogen (NOx), sulphur dioxide (SO2), lead (Pb), the volatile organic compounds (VOC’s – mostly hydrocarbons HC’s), and smoke. CO results from incomplete combustion of fuel and can have detrimental health effects, particularly in confined spaces and urban areas. NOx results from the high temperatures in car engines and contributes to photochemical air pollution and acid rain. Hydrocarbons HC’s enter the atmosphere as unburned fuel and as evaporation from vehicles and storage tanks. They play an important role in the formation of photochemical oxidants, such as ozone, which irritate eyes in smog, damage plants and contribute to acidification and global warming. Road transport is the main contributor to emissions of nitrogen dioxide and benzene (HC) in cities and is the major reason for non-compliance with current European Union (EU) limit values for these pollutants. (5,6)

1.6.4 Social impacts
Streets have always been meeting places; indeed democracy was born in the Agora, the market-place in Athens. The urban street has been a rallying point, a community place, the place for children’s games and sport, buying and selling, celebrations and processions, music and parades, friendship and community spirit. A street with little traffic and many families promotes a rich social climate and a strong sense of community. Residents of a street with low traffic show an appreciative awareness of and care for their physical environment. However, heavy traffic causes people to withdraw from the physical environment. A study in the USA showed that as traffic volumes increased, social contacts on the street declined. There were also differences in behaviour. Where traffic was heavier, people no longer lingered on the pavement, they did not use their front gardens, and those living near the busiest roads in urban cities spent less time in the front rooms of their houses (6). In other words, in order to protect themselves, people stopped trying to use the street in the old ways and, except where cars were banned or controlled, moved their meeting places inside or abandoned meeting altogether. (7,8)

The most obvious obstacle to social contacts is a motorway, fenced road, or railway line which pedestrians cannot cross. A road which pedestrians can cross may also be a formidable obstacle, especially for the elderly, young children and their mothers. These groups are less likely to have access to a car and are therefore more dependent on contacts within walking distance. Even if a pedestrian crossing or subway is provided, the detour involved may well discourage these less mobile groups (6,9). The cumulative effect of transport on streets and neighbourhoods has made them an unpleasant place to spend time. Space which once was an important possession of local people has been taken from them over the years and made the preserve of people in cars that happen to be passing through. Children no longer play on the pavement or make unaccompanied journeys along the street to school. A reduction in the number of people walking through the streets creates ripe conditions for growing crime rates, and a vicious circle may develop which further reduces the number of journeys made on foot (6,9).

1.6.5 Defining sustainable urban transport
The concept of sustainable transportation is a reaction to the undesirable impacts of urban transport. One of the first international organisations to take a close look at the concept of sustainable transport was the Organisation fore Economic Co-operation and Development OECD. In 1996, the OECD organised the International Conference towards Sustainable Transportation, at which the Canadian government, provided a preliminary definition of environmentally sustainable transport (EST), as follows: “Transportation that does not endanger public health or ecosystems and meets mobility needs consistent with (a) use of renewable resources at or below their rates of regeneration and (b) use of non-renewable resources at or below the rates of development of renewable substitutes.” The OECD set out 6 criteria for the attainment of EST by the target year of 2030:

1. Transport-related emissions of nitrogen oxides (NOx) must be reduced to the extent that the objectives for ambient nitrogen dioxide and for ozone levels as well as for nitrogen deposition are achieved.
2. Emissions of volatile organic compounds (VOCs) must be reduced to the extent that excessive ozone levels are avoided, and emissions of carcinogenic VOCs from all movement of all vehicles have been reduced to meet acceptable risk levels.
3. Climate change is being prevented by achieving per-capita carbon dioxide emissions from fossil fuel use for transportation consistent with the global protection goals for the atmosphere.
4. Emissions of particulates have been reduced to the extent that harmful ambient air levels are avoided.
5. Land surface in urban areas is used for the movement, maintenance, and storage of motorised vehicles, including public transport vehicles such that the objectives for ecosystem protection are met.
6. Noise caused by transportation should not result in outdoor noise levels that present a health concern or serious nuisance (10).

According to the World Bank, sustainable transport has three components: economic sustainability, which involves creating incentives for efficient response to needs; environmental sustainability, which involves promoting more liveable settlements and reducing adverse external effects of transport; and social sustainability, which focuses on the reduction of poverty. This definition applies to all issues relevant to sustainability and it addresses the issue of “whether transportation’s long-term environmental impacts will result in future generations inheriting significantly fewer resources than those available to their predecessors.” (10)

In 2002, the Canadian government, together with the Canadian Centre for Sustainable Development, came up with another definition which is probably the most widely shared and complete definition, and which outlines the basic principles of a sustainable transportation system. It defines a sustainable transportation system as one that:

• allows the basic access needs of individuals and societies to be met safely and in a manner consistent with human and ecosystem health, and with equity within and between generations
• is affordable, operates efficiently, offers choice of transport mode, and supports a vibrant economy
• limits emissions and waste within the planet’s ability to absorb them, minimizes consumption of non-renewable resources, limits consumption of renewable resources to the sustainable yield level, reuses and recycles its components, and minimizes the use of land and the production of noise

All these definitions of sustainable definition address the effects of transport on society and the environment and the need to substantially reduce these impacts. The focus is on ensuring that future generations have access to the same level of resources and environmental quality and present generation.

1.6.6 Achieving sustainable urban transport
The issue of urban transport has to be addressed in a comprehensive manner, taking into account physical, economic and social impacts and devising new strategies for sustainable urban communities. Local authorities and governments have been trying to reverse current trends. They are applying traffic calming measures with the aim of reducing speeds and discouraging traffic from using residential streets when there are other routes available. Often this is an essential element in revitalising town centres and inner city areas. Another approach to reducing the effects of road traffic is to build bypasses for small towns. However, some evidence suggests that the problems may reappear elsewhere (in effect being pushed along the road) and the bypassed centre may wither because of the loss of trade (6). High capacity, low energy-consuming transit modes need to be introduced in urban centres and high density areas, while the use of private automobiles must be curtailed either by regulation or pricing policies. The automotive industry must continue to improve engine performance while developing alternative propulsion systems that do not rely on hydrocarbons. Communities must be designed which minimise the need for travel. Only by moving in these directions can we hope to achieve a future of sustainable urban transport.

1.6.7 References

back to top