Sustainable Transportation Research Paper

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. (WCED 1987, p. 43)

This and most other definitions constitute a normative concept of intergenerational responsibility or fairness. It is also significant that the context of the Brundtland definition was the issue of economic development and resulting conflicts with the environment. The concept of sustainability balances the right of less advantaged nations to economic development, with the imperative to preserve the resources, especially the environmental resources, that future generations will need for their own well-being. Thus, a concept of equity, both intergenerational and international, has been inherent in the idea of sustainability since its inception.

Sustainability pertains to the responsibility of an entire generation of society to future generations; whether it can meaningfully be applied to a single area of human activity such as transportation has been a subject of debate. That is, sustainability must be satisfied by the integral activities of a society and so, in this sense, it is not possible to judge whether one sector of society is sustainable on its own. On the other hand, it would not be possible for society to achieve sustainability, at least not in the long run, if even one sector were not sustainable. Thus, sustainable transportation may be considered a necessary but not sufficient condition for the sustainability of society.

Economic development has been central to the issue of sustainability since its inception. Economists have argued that the Bruntland definition implies nondecreasing well-being, and some have suggested that measures such as gross domestic product or real consumption per capita may be appropriate measures of sustainable growth. Others argue that well-being must be defined more broadly to include other areas of human development, such as education, health, environmental quality, and social justice (e.g., Pearce et al. 1994). In this broader view, the human institutions passed from one generation to another are just as important a resource as any other institution.

The question of how to translate the Brundtland imperative into a measurable and verifiable concept is still being worked out. In the economic literature, efforts to resolve this question have revolved around the concepts of weak and strong sustainability. The doctrine of weak sustainability holds that manufactured capital (machinery, buildings, infrastructure, etc.) is perfectly substitutable for natural capital (natural and environmental resources). This view holds not only that manufactured capital can be substituted for resources such as coal or iron ore, but that it can be substituted for environmental functions such as the ability of the air to absorb pollution or even the atmospheric and ocean processes that produce the global climate. Strong sustainability, on the other hand, maintains that there are limits to the substitutability of manufactured and natural capital. In particular, it maintains that there are certain environmental processes and functions that must be protected and preserved because they cannot be replaced by created capital. Ecosystems and biodiversity are often-cited examples of irreplaceable environmental processes.

How economic growth and expanding human welfare could continue indefinitely in the face of intensifying environmental impacts and finite natural resources is a central question for theorists and researchers. Human activity, and especially economic activity, are inextricably linked to the environment by the ever-expanding quantities of natural resources extracted, processed and consumed (Pearce and Warford 1993). Because mass and energy must be conserved due to the laws of nature, all the resources and energy used must end up somewhere in the form of waste (unless recycled). A useful way to conceive of the relationship between human activity and the environment is to imagine a coefficient of environmental intensity that relates total environmental damage to the total level of activity, perhaps measured, albeit incompletely by gross domestic product. Similarly, one can imagine a coefficient of natural resource requirements for input to the world economy. Because emissions controls, recycling, and greater energy efficiency can change the environmental coefficient, technological change and behavioral change clearly must play a key role in achieving sustainability. If the environmental coefficient can be reduced as fast or faster than the growth of human activity, and if increasing efficiency and recycling can similarly reduce the requirements for energy and other natural resource inputs, then it should be possible for human well-being to expand in a sustainable way.

The above line of reasoning identifies sustainability not as an equilibrium or final state of being able to continue indefinitely, but as a steady state in which the rate of improvement exceeds the rate of exhaustion of manufactured capital, natural resources, environmental services, and human and institutional capital. In this view, sustainability requires reducing demands on the environment per unit of activity as fast as or faster than the growth in activity. It requires increasing the efficiency of energy and resource use, or expanding the scope of useful resources at a rate at least as fast as the growth of human activity. It may even be interpreted more broadly as a matter of improving human institutions faster than challenges emerge to threaten them. While these concepts can and have been applied to transportation, a comprehensive theory of sustainable transportation that is measurable and verifiable is still yet to emerge.

1. Sustainable Transportation And Economic Development

Throughout history, the expansion and improvement of transportations systems has been an engine of economic development (Greene and Wegener 1997). The fast and reliable movement of persons and commodities contributes more than simply a reduction in the costs of production. It facilitates the reorganization of production and consumption to permit specialization, scale economies, inventory reduction, and more. Today, transportation activity continues to increase at roughly the rate of economic growth in both the developed and developing economies.

Motorized transport is the source of essentially all the demands transportation imposes on natural and environmental resources. The motorization of transport, fully accomplished in the developed economies during the twentieth century, is now proceeding rapidly in the developing world. In 1950, 90 percent of the world’s 50 million motor vehicles could be found in Europe or the United States. Today, half of the world’s roughly 700 million vehicles are to be found outside of those countries. The developing economies own more than one-third of the world’s motor vehicles, and vehicle ownership outside of the developed economies is growing at twice the rates seen in the developed economies. The global potential for motorization is enormous. In developed economies, motor vehicle ownership rates average 500 per 1,000 persons. In the US, there is more than one motor vehicle per person of driving age. Ownership rates in the developing economies are about one-twentieth as high.

Expansion of modern, motorized transportation in the developing economies appears to be essential to their sustainable development. The World Bank has identified three broad types of sustainability in considering transport investments in developing countries: (a) economic and financial sustainability; (b) environmental sustainability; and, (c) social sustainability (World Bank 1996). These categories reflect the view that to be sustainable, transportation systems must have stable financing in the context of market economies, must address the many adverse impacts of transportation on health and ecosystems, and must serve the mobility needs of the poor as well as those with the ability to pay.

2. Environmentally Sustainable Transport

Transportation systems have diverse and widespread impacts on the environment, affecting climate, air and water quality, noise, habitats, and biodiversity. Worldwide, transportation accounts for one-fourth of global carbon dioxide emissions. Scientists have concluded that the accumulation of carbon dioxide and other less common anthropogenic greenhouse gases in the world’s atmosphere since the onset of the industrial revolution are now having a perceptible impact on the earth’s climate. While it is not yet clear what the impacts on climate will be, they are likely to include increases in storm activity, changes in the patterns of rainfall, a general warming leading to higher sea levels, and other potentially harmful or even catastrophic effects. The quantity of carbon dioxide emission produced by transportation depends on the carbon content of the transportation fuels and the energy efficiency of transport systems. Today, motorized transport is entirely dependent on fossil fuels. The combustion of fossil fuels is the predominant source of greenhouse gas emissions from human activities. A typical passenger car adds 1 to 2 tonnes of carbon to the atmosphere each year. Despite 50–100 percent increases in the fuel economy of automobiles over the past 30 years, there appears to be no prospect of reducing global greenhouse gas emissions from transportation for at least 20 to 30 years. Clearly, continuing to force alterations in the earth’s climate systems in unpredictable ways does not satisfy the sustainability doctrine.

Transportation is a major source of local and regional air pollution. In Europe and the United States, transportation vehicles emit roughly 45 percent of nitrogen oxides and 40 percent of volatile organic compounds that mix in the atmosphere to form ozone, a pollutant that exacerbates a variety of respiratory problems and causes damage to vegetation as well. Air pollutants from transport have an immediate impact on human health and on vegetation. Ozone pollution has been observed to change the distribution of tree species in forests, retard the growth of vegetation, and damage crops. Prolonged exposure to ozone is strongly believed to reduce biodiversity of plant communities and diminish variability in their gene pools (NRC 1997). Emissions of oxides of nitrogen and sulfur from motor vehicles contribute to acid rain with widespread negative impacts on terrestrial and aquatic ecosystems. Volatile organic compounds also include a number of toxic pollutants, including known and suspected carcinogens, such as benzene, formaldehyde, cyanide, and dioxin.

Transportation vehicles produce significant quantities of fine particulate pollution via several mechanisms. Vehicle tailpipe emissions contain particles produced by incomplete combustion. Particles and aerosols are formed when certain motor vehicle emissions react in the air. Finally, dust from roads is a major source of air-borne particulate matter. Fine particulate matter can be inhaled deeply into the lungs, contributing to a variety of respiratory problems. Epidemiological studies have correlated elevated morbidity and mortality rates with long-term, low-level exposure to fine particulates, as well as to episodes of acute pollution, suggesting that particulate pollution may be the most serious form of motor vehicle pollution from the perspective of human health (NRC 1997).

Since the 1950s, enormous technological progress has been made in reducing the pollutant emissions from new transportation vehicles. A properly operating motor vehicle manufactured in 2000 produces 1 percent to 10 percent of the pollution (depending on the pollutant) of a car made 35 years earlier. Still, even this rate of progress has been insufficient to achieve air quality standards in many urban areas because the growth of travel has outpaced the rate of technological improvement. Further significant improvements in conventional vehicles and fuels will be made from 2000 to 2010. Yet achieving sustainability will probably require entirely new energy sources and propulsion technologies ultimately.

3. Solid Waste

Transportation infrastructure and vehicles generate enormous amounts of solid waste. Some of this waste, such as iron and steel, has a long history of recycling. Other components like plastics most often end up in landfills or incinerators. Waste oil and fluids, batteries, and other components often contain toxic materials that pose serious health and environmental hazards if not properly disposed of. The maintenance and reconstruction of transportation facilities also generate substantial quantities of mostly asphalt and concrete waste. Not only increased recycling, but lifecycle management of materials for transportation systems has been recognized as essential to achieving sustainable transportation systems (OECD 1997).

4. Noise

It may seem odd to include noise among the issues affecting transportation’s sustainability. Noise, after all, is inherently transitory and its impacts on society and the environment would seem to be also. On the other hand, transportation systems operate more or less continuously, generating noise around the clock. Studies carried out in Europe have shown that about 20 percent of the population are exposed to daytime transport noise exceeding acceptable levels (65 dB(A)) (European Commission 1995). Another 170 million are exposed to noise levels that cause serious annoyance as defined by the World Health Organization. Road noise is the dominant source, followed by rail and air transport. Furthermore, data for the 1980– 95 period showed no significant improvement in exposure to traffic noise for the population of Europe. The principal impacts of transportation noise are annoyance, interference with work and sleep and, less commonly, hearing loss. Estimates of the costs of noise pollution in Europe range between 0.1 percent and 2 percent of GDP.

5. Natural Resources

Transportation is a major consumer of two critical, limited resources: land and petroleum. Worldwide, transportation accounts for 56 percent of global petroleum consumption and between 1973 and 1997 was responsible for all of the increase in world oil consumption (IEA 2000). Recent assessments of the world’s supplies of conventional petroleum indicate that sometime between 2005 and 2025, the world will have consumed half of all the conventional petroleum that is known or believed to exist (EIA 2000 and USGS 2000). Once this point is passed, it is virtually certain that production of conventional petroleum will begin to decline, and unconventional energy sources will have to be substituted at an increasing rate. The world’s transportation system, which is 97 percent dependent on petroleum for energy, will not be sustainable unless it can make a transition to alternative energy sources. While there are more than adequate resources of fossil fuels that can be converted to transport fuels (e.g., coal, oil shale, and tar sands), the greater environmental impacts associated with using these fuels raises serious questions about the sustainability of a motorized world transport system based on fossil fuels.

Perhaps even more serious are the questions raised by transportation systems’ expanding direct and indirect uses of land. Not only does transportation infrastructure such as road, airports, and railroad tracks, occupy millions of hectares of land, but the infrastructure and vehicles that use it have significant impacts on surrounding ecosystems. Linear transportation structures serve as deadly barriers to the migration and movements of species, and alter water flow and groundwater. But perhaps more importantly, transportation infrastructure indirectly alters the patterns and density of human settlements, with even more pervasive impacts on ecosystems and biodiversity (NRC 1997).

6. Sustainable Communities

Transportation is recognized as a key element of sustainable communities (PCSD 1997). Human development patterns and the transportation systems that serve them are strongly interdependent. Transportation choices made by present generations will constrain the opportunities of future generations because built environments can be changed only slowly and at great cost. The high level of mobility provided by automotive transport has engendered dispersed low-density development, sometimes referred to as sprawl. The area of built-up urban land in the United States increased by an estimated 14 million acres between 1982 and 1992, driven in large part by the expansion of highway infrastructure (BTS 1996, p. 162).

As demand for mobility has continued to grow, while the land available for expanding transportation infrastructure in urban areas has not, chronic congestion has become a major problem in cities around the world. Increasing levels of traffic congestion are not only a source of stress and waste the time of present generations, but can restrict the opportunities for mobility of future generations. If the capacities of transportation systems cannot be expanded to accommodate future growth without incurring unacceptable trade-offs, the options available to future generations will be diminished.

7. Safety

Safety must also be included in assessing the sustainability of transportation systems (e.g., Black 2000). While absolutely compelling as a human tragedy, the sense in which transportation safety is a sustainability issue may be less obvious. Globally, there are about 700,000 motor vehicle fatalities annually, and many millions of serious injuries. On the other hand, fatality rates (e.g., per 100,000 vehicle miles) are generally declining. In developed economies such as the United States, recent years have seen declines in total fatalities even while motor vehicle travel and population size continue to grow. In countries undergoing rapid motorization, however, total fatalities are increasing at the same time rates are declining. When both fatalities and fatality rates are increasing, the sustainability of transportation systems is in question. The resource at issue is human life itself, and the needs of future generations would clearly appear to be threatened by increasingly unsafe transportation systems. Where both total fatalities and fatality rates are declining, an argument can be made for sustainability. Without a doubt, safety is the single most important problem facing transportation. Yet, to date there is little agreement on how safety should be interpreted in the context of the sustainability doctrine.

8. Equity

Equity among generations is clearly integral to the concept of sustainability. For sustainability to exclude equity considerations among individuals within a generation would be inherently inconsistent. The Charter of European Cities and Towns Towards Sustainability states that the goals of sustainable development are ‘… to achieve social justice, sustainable economies, and environmental sustainability’ (Greene and Wegener 1997). Furthermore, the context of the Brundtland sustainability definition was clearly the need to preserve the global environment while permitting developing countries the economic development that is their right. Clearly social justice and particularly equity have been integral to the concept of sustainability. It has been argued that the concept of intergenerational fairness embodied in sustainability, in fact arises from a societal commitment to equality of opportunity among contemporaries (Howarth 1997). Exactly how equity concerns are to be incorporated in an operating definition of sustainability has yet to be resolved, as have the implications for transportation. At a minimum, equity considerations include the interests of developing economies to pursue higher levels of mobility, as well as the needs of disadvantaged citizens for access to mobility in all societies.

9. Measuring Sustainability

If policies are to be formulated and implemented to achieve sustainable transportation, indicators must be found to measure it (OECD 1994). If the steady-state concept of sustainability is accepted, these indicators should show:

whether the world’s environmental resources are being reduced by transportation’s impacts on air or water pollution;

whether the global climate is being altered by greenhouse gas emissions;

whether habitats are being destroyed through direct or indirect land-use impacts; and

whether the generation of solid waste is increasing or being restrained by recycling.

Indicators must show whether the fundamental natural resources required for transportation, such as energy and land, are being expanded as fast or faster than they are being consumed, and whether transportation systems are being developed and managed so as to enhance social equity by improving access to mobility for all. Until the consequences of transportation for sustainability are made visible measuring them, progress toward sustainable transportation will be limited.

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