Author: Dr. Jean-Paul Rodrigue
1. The Issue of Transport and the Environment
The issue of transportation and the environment is paradoxical in nature since transportation conveys substantial socioeconomic benefits, but at the same time transportation is impacting environmental systems. From one side, transportation activities support increasing mobility demands for passengers and freight, while on the other, transport activities are associated with growing levels of environmental externalities. Further, environmental conditions have an impact on transportation systems in terms of operating conditions and infrastructure requirements such as construction and maintenance (see Transportation and Space for a review of such constraints).
The growth of personal and freight mobility in recent decades have expanded the role of transportation as a source of emission of pollutants and their multiple impacts on the environment. These impacts fall within three categories:
- Direct impacts. The immediate consequence of transport activities on the environment where the cause and effect relationship is generally clear and well understood. For instance, noise and carbon monoxide emissions are known to have direct harmful effects.
- Indirect impacts. The secondary (or tertiary) effects of transport activities on environmental systems. They are often of higher consequence than direct impacts, but the involved relationships are often misunderstood and more difficult to establish. For instance, particulates are mostly the outcome of incomplete combustion in an internal combustion engine are indirectly linked with respiratory and cardiovascular problems since they contribute among other factors to such conditions.
- Cumulative impacts. The additive, multiplicative or synergetic consequences of transport activities. They take into account of the varied effects of direct and indirect impacts on an ecosystem, which are often unpredicted. Climate change, with complex causes and consequences, is the cumulative impact of several natural and anthropogenic factors, in which transportation plays a role. 15% of global CO2 emissions are attributed to the transport sector.
The complexities of the impacts have led to much controversy in environmental policy, the role of transportation and mitigation strategies. This is made even more complex by the fact that priorities between environmental and economic considerations shift in time. The transportation sector is often subsidized by the public sector, especially through the construction and maintenance of road infrastructure, which tend to be free of access. Sometimes, public stakes in transport modes, terminals and infrastructure can be at odd with environmental issues. If the owner and the regulator are the same (different branches of the government), then there is a risk that regulations will not be effectively complied to.
Total costs incurred by transportation activities, notably environmental damage, are generally not fully assumed by the users. The lack of consideration of the real costs of transportation could explain several environmental problems. Yet, a complex hierarchy of costs is involved, ranging from internal (mostly operations), compliance (abiding to regulations), contingent (risk of an event such as a spill) to external (assumed by the society). For instance, external costs account on average for more than 30% of the estimated automobile ownership and operating costs. If environmental costs are not included in this appraisal, the usage of the car is consequently subsidized by the society and costs accumulate as environmental pollution. This requires due consideration as the number of vehicles, especially automobiles, is steadily increasing.
2. The Transport – Environment Link
The relationships between transport and the environment are multidimensional. Some aspects are unknown and some new findings may lead to drastic changes in environmental policies. Historically, transportation was associated with a few negative environmental impacts. For instance, the setting of large navies of sailships was responsible for a level of deforestation in Western Europe and North America from the 16th to the 19th centuries. Urbanization in the 19th century and the reliance on horses created problems concerning the disposal of manure. Further, industrialization and the development of steam engines lead to pollution (e.g. sooth) near ports and rail yards. It is however only in the 20th century that a comprehensive perspective about the links between transportation and the environment emerged, particularly with the massive diffusion of transportation modes such as the automobile and the airplane. The 1960s and 1970s were crucial decades in the realization of the negative environmental impacts of human activities and the need for regulations.
From an infrastructure perspective, the first comprehensive environmental regulation, the National Environmental Policy Act (NEPA), was set in 1970 and required all federal agencies of the US government to make environmental impact assessments of their actions. Since an agency such as the Department of Transportation is an important provider and manager of transportation infrastructure, this legislation had substantial impacts on how transportation is assessed to be linked with environmental issues. One clear consequence was the growth in the length and the complexity of approving transport infrastructure projects to insure they meet environmental standards. Opponents of a project could also use the regulatory framework to delay, or even cancel its construction and on occasion change its design parameters (e.g. size). An unintended consequence was that the complexity of environmental regulations tend to impair innovations and incite current providers to keep existing infrastructure and facilities for the concern to trigger an uncertain environmental review with a new project.
From an operational perspective, the Clean Air Act of 1970 set clear air quality standards and expectations for both stationary (e.g. a power plant) and mobile (e.g. an automobile) sources of air pollutants. For transportation, it immediately set emissions standards from a list of acknowledged pollutants such as carbon dioxide, volatile organic compounds and nitrogen oxide. The outcome was a rapid decline of air pollutant emissions by the transportation sector. The Clear Water Act of 1977 provided a similar regulatory environment concerning water pollution and the ability to build infrastructures over wetlands.
The 1990s were characterized by a realization of global environmental issues, epitomized by the growing concerns between anthropogenic effects and climate change. Transportation also became an important dimension of the concept of sustainability, which has become a core focus of transport activities, ranging from vehicle emissions to green supply chain management practices. These impending developments require a deep understanding of the reciprocal influence between the physical environment and transport infrastructures and yet this understanding is often lacking. The main factors considered in the physical environment are geographical location, topography, geological structure, climate, hydrology, soil, natural vegetation and animal life.
The environmental dimensions of transportation are related to the causes, the activities, the outputs and the results of transport systems. Establishing linkages between environmental dimensions is a difficult undertaking. For instance, to what extent carbon dioxide emissions are linked to land use patterns? Furthermore, transportation is embedded in environmental cycles, notably over the carbon cycle where carbon flows from one element of the biosphere, like the atmosphere, to another like the ecosphere, where it can be accumulated (permanently of temporarily) or passed on. The relationships between transport and the environment are also complicated by two observations:
- Level of contribution. Transport activities contribute among other anthropogenic and natural causes, directly, indirectly and cumulatively to environmental problems. In some cases, they may be a dominant factor, while in others their role is marginal and difficult to establish.
- Scale of impact. Transport activities contribute at different geographical scales to environmental problems , ranging from local (noise and CO emissions) to global (climate change), not forgetting continental / national / regional problems (smog and acid rain).
Establishing environmental policies for transportation thus have to take account of the level of contribution and the geographical scale, otherwise some policies may just move the problems elsewhere and have unintended consequences. A noted example are environmental policies in advanced economies inciting the relocation of some activities with high environmental externalities (e.g. steel making) in developing economies. This transfer the problem from one location to another. Still, such as transfer usually involves new equipment and technologies that are usually less impacting. Even if an administrative division (municipality, county, state) has adequate environmental enforcement policies, the geographical scale of an environmental impact (notably air pollutants) goes beyond established jurisdictions.
The structure of the transport network, the modes used and traffic levels are the main factors of environmental impact of transportation. Networks influence the spatial distribution of emissions (e.g. centralized versus diffuse networks), while modes relate to the nature of the emissions and the traffic the intensity of these emissions. In addition to these environmental impacts, economic and industrial processes sustaining the transport system must be considered. These include the extraction and production of fuels, vehicles and construction materials, some of which are very energy intensive (e.g. aluminum), and the disposal of vehicles, parts and the provision of infrastructure. They all have a life cycle timing their production, utilization and disposal. Thus, the evaluation of the link between transport and the environment without the consideration of cycles in the environment and in the product life alike is likely to convey a limited overview of the situation and may even lead to incorrect appraisal, policies and mitigation strategies.
3. Environmental Dimensions
Transportation activities support increasing mobility demands for passengers and freight, notably in urban areas. But transport activities have resulted in growing levels of motorization and congestion. As a result, the transportation sector is becoming increasingly linked to environmental problems. The most important impacts include:
What is known as the greenhouse effect is a fundamental component of the regulation of global climate and is a naturally occurring process that involves partially retaining heat in the earth’s atmosphere. These include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and halocarbons. The quantity of conventional greenhouse gases released into the atmosphere has increased substantially since the industrial revolution and particularly over the last 25 years. The respective impacts of greenhouse gases is further complicated by differences in their atmospheric lifetime (or residence time), which is the time they spend in the atmosphere before decaying or being absorbed by biological or chemical processes. For CO2, it can range between 5 and 200 years, while it is about 12 years for methane and 114 years for N2O. For halocarbons, such as Chlorofluorocarbons, it is at least 45 years.
The activities of the transport industry release several million tons of gases each year into the atmosphere, accounting between 25 and 30% of all greenhouse gas emissions. There is an ongoing debate to what extent these emissions are linked to climate change, but the debate relates more to the extent of these impacts than their nature. Some gases, particularly nitrogen oxide, also participate in depleting the stratospheric ozone (O3) layer which naturally screens the earth’s surface from ultraviolet radiation. In addition to be a contributor to climate change, transportation is also impacted by it, particularly over infrastructure (e.g. more floods due to rising sea levels) and operations (harsher operating conditions).
Highway vehicles, marine engines, locomotives and aircraft are the sources of pollution in the form of gas and particulate matters emissions that affects air quality causing damage to human health. The most common include lead (Pb), carbon monoxide (CO), nitrogen oxides (NOx), silicon tetraflouride (SF6), benzene and volatile components (BTX), heavy metals (zinc, chrome, copper and cadmium) and particulate matters (ash, dust). Lead emissions have declined substantially in the last decades as its use as an anti-knock agent for gasoline was banned in the majority of countries from the 1980s. The main factors behind this ban were that tetraethyl lead (the form used as a fuel additive) was associated with neurotoxic effects on human being and that it impaired catalytic converters.
Toxic air pollutants are associated with cancer, cardiovascular, respiratory and neurological diseases. Carbon monoxide (CO) when inhaled reduces the availability of oxygen in the circulatory system and can be extremely harmful. Nitrogen dioxide (NO2) emissions from transportation sources reduces lung function, affect the respiratory immune defense system and increases the risk of respiratory problems. The emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) in the atmosphere form various acidic compounds that when mixed in cloud water creates acid rain. Acid precipitation has detrimental effects on the built environment, reduces agricultural crop yields and causes forest decline.
Smog is a mixture of solid and liquid fog and smoke particles formed through the accumulation of carbon monoxide, ozone, hydrocarbons, volatile organic compounds, nitrogen oxides, sulfur oxide, water, particulates, and other chemical pollutants. The reduction of visibility caused by smog has a number of adverse impacts on the quality of life and the attractiveness of tourist sites. Particulate emissions in the form of dust emanating from vehicle exhaust as well as from non-exhaust sources such as vehicle and road abrasion have an impact on air quality. The physical and chemical properties of particulates are associated with health risks such as respiratory problems, skin irritations, eyes inflammations, blood clotting and various types of allergies. Smog is often exacerbated by local physical and meteorological conditions which can create periods of high smog concentration and public responses to temporarily mitigate them, such as restricting automobile use.
While air quality issues have been comprehensively addressed in advanced economies, with substantial declines in the emissions of a wide range of pollutants. In developing economies, rapid motorization has shifted the concern to the large cities of China and India among those the most impacted by the deterioration of air quality.
Noise represents the general effect of irregular and chaotic sounds on people as well as animal life. Basically, noise is an undesirable sound.The acoustic measure of the intensity of noise is expressed in decibel, db, with a scale ranging from 1 db to 120 db. Long term exposure to noise levels above 75 decibels (dB) seriously hampers hearing and affects human physical and psychological wellbeing. Noise emanating from the movement of transport vehicles and the operations of ports, airports and railyards affects human health, through an increase in the risk of cardiovascular diseases. Ambient noise is a frequent result of road transportation in urban areas, which is the cumulative outcome of all the noise generated by vehicles (ranging from 45 to 65 db), which impairs the quality of life and thus property values. Falling land values nearby acute noise sources such as airports are often noted. Many noise regulations impose mitigation if noise reach a defined level, such as sound walls and other soundproofing techniques.
Transport activities have an impact on hydrological conditions and water quality. Fuel, chemical and other hazardous particulates discarded from aircraft, cars, trucks and trains or from port and airport terminal operations can contaminate hydrographic systems.
Because demand for maritime shipping has increased, marine transport emissions represent the most important segment of water quality impact of the transportation sector. The main effects of marine transport operations on water quality predominantly arise from dredging, waste, ballast waters and oil spills. Dredging is the process of deepening harbor channels by removing sediments from the bed of a body of water. Dredging is essential to create and maintain sufficient water depth for shipping operations and port accessibility. Dredging activities have a two-fold negative impact on the marine environment. They modify the hydrology by creating turbidity that can affect the marine biological diversity. The contaminated sediments and water raised by dredging require spoil disposal sites and decontamination techniques. Waste generated by the operations of vessels at sea or at ports cause serious environmental problems, since they can contain a very high level of bacteria that can be hazardous for public health as well as marine ecosystems when discharged in waters.
Besides, various types of garbage containing metals and plastic are not easily biodegradable. They can persist on the sea surface for long periods of time and can be a serious impediment for maritime navigation in inland waterways and at sea and affecting as well berthing operations. Ballast waters are required to control ship’s stability and draft and to modify their center of gravity in relation to cargo carried and the variance in weight distribution. Ballast waters acquired in a region may contain invasive aquatic species that, when discharged in another region may thrive in a new marine environment and disrupt the natural marine ecosystem. Invasive species have resulted in major changes in nearshore ecosystems, especially in coastal lagoons and inlets. Major oil spills from oil cargo vessel accidents are one of the most serious problems of pollution from maritime transport activities.
The environmental impact of transportation on soil quality, particularly soil erosion and soil contamination. Coastal transport facilities have significant impacts on soil erosion. Shipping activities are modifying the scale and scope of wave actions leading to damage in confined channels such as river banks. Highway construction or lessening surface grades for port and airport developments have led to important loss of fertile land. Soil contamination can occur through the use of toxic materials by the transport industry. Fuel and oil spills from motor vehicles are washed on road sides and enter the soil. Chemicals used for the preservation of wooden railroad ties may enter into the soil. Hazardous materials and heavy metals have been found in areas contiguous to railroads, ports and airports.
Transportation also influences biodiversity. The need for construction materials and the development of land-based transportation has led to deforestation. Many transport routes have required draining land, thus reducing wetland areas and driving-out water plant species. The need to maintain road and rail right-of-way or to stabilize slope along transport facilities has resulted in restricting growth of certain plants or has produced changes in plants with the introduction of new species different from those which originally grew in the areas. Many animal species are becoming endangered as a result of changes in their natural habitats and reduction of ranges due to the fragmentation of their habitat by transportation infrastructures.
Transportation facilities have an impact on the urban landscape. The development of port and airport infrastructure is significant features of the urban and peri-urban built environment. Social and economic cohesion can be severed when new transport facilities such as elevated train and highway structures cut across an existing urban community. Arteries or transport terminals can define urban borders and produce segregation. Major transport facilities can affect the quality of urban life by creating physical barriers, increasing noise levels, generating odors, reducing urban aesthetic and affecting the built heritage. The expansion of logistics activities has also be an indirect factor of land take in suburban and periurban areas.
4. Environmental Externalities
Externalities are an economic concept that refers to the activities of a group that have consequences, positive or negative, intended or unintended, on other groups. These consequences, particularly if they are negative, are not assumed by those causing them. The impacts are therefore externalized. A common example of a positive externality concerns technology since it obviously benefits the innovative firm but also the whole economy through various productivity improvements or improved convenience. Negative externalities have a lot of relevance over environmental issues, since many of the negative consequences of pollution are assumed by the whole society.
The environmental externalities of transportation include the consideration of physical measures of environmental damage and the evaluation of involved costs for the society. The main fallacy underlined by externalities is that the costs attributed to a few sources (e.g. users of cars) must be burdened by many (users and nonusers alike). Knowing the sources of environmental externalities is a relatively easy undertaking, while the evaluation of damage and other costs has not yet reached comparative standards among governmental and non-governmental agencies. The challenge resides over three issues:
- Relationships. The nature and extent of the relationships between transport and the environment has to be considered. This is particularly complex as most environmental relationships tend to be indirect and cumulative.
- Quantification. Relationships have to be quantified and also a value to environmental externalities should be appraised. This highly challenging as only general figures, much subject to debate, can be assessed. The quantification of economic, social and environmental costs therefore subject to much contention.
- Mitigation. The level and extent of corrective actions that can be taken to alleviate environmental externalities linked to transportation, usually in a manner where those contributing bear the consequences of their activities. In view of the two above points, attempts at regulation, particularly if they involve a comprehensive framework (multinational and multisector), have not reached a significant consensus. Alternatively, a consensus may be reached about the nature of an environmental externality, but not about its mitigation.
The costs of environmental externalities can be considered from economic, social and environmental dimensions. The basic types of transportation externalities attributed to the environment fall within air pollution, water pollution, noise, and hazardous materials.Establishing and quantifying environmental externalities is a complex undertaking. Quantification is only at its preliminary stage and many have used this argument to differ the application of several environmental policies by lobbying governments (e.g. acid rain, CFCs and most importantly, climate change). Additionally, the wider the geographical scale the more complex the environmental problem becomes, since it involves cross-jurisdictional issues. Recent attempts to reach a consensus about climate change have underlined the complexity of multilateral environmental agreements.
The sources / emitters of pollutants rarely bear the consequences of their impacts. This has several implications. First, when specific sources are concerned, like road transportation, users only take account of the direct costs of modal ownership like a car (vehicle, fuel, insurance, etc.). Ownership is often the only entry and utilization cost for several transportation modes. The society generally assumes the role of providing and maintaining infrastructure and other indirect costs like damage to structures and infrastructure, losses in productivity, cleanup, health services and damage to ecosystems. Second, the geographic separation between sources and recipients is often acute. Acid rains and climate change are obvious examples. On a local level, a community may be affected by noise levels well over its own contribution (notably near major highways), while another (e.g. suburbs) may be affected in a very marginal way and still significantly contributes to noise elsewhere during commuting.
There is a tendency towards a shift from direct to indirect consequences for environmental externalities, as of total costs involved. For instance, the absolute levels of air pollutants emissions have considerably dropped in developed countries. The problem of source reduction by vehicles was addressed because it was a straightforward cause of air pollutants emissions. This has tended to displace problems elsewhere and developed new types of externalities. Thus, the relative share of air pollution impacts is lessening, but not the number of vehicles, investment in infrastructure or noise levels, which have their own externalities. Reductions in the relative importance of one type of externality redirect the focus on other types that were less addressed, but probably as important in the overall impacts of transport over the environment.
Transfers and additions of costs are very common attributes of environmental externalities. Trying to lessen economic costs will either lessen or worsen social and environmental costs, depending on the externality. In the context of limited resources, the distribution of economic, social and environmental costs takes an important role as what type of damage is most acceptable and in what proportions. It is clear from past strategies that several economic costs have been minimized, notably for producers and users, while social and environmental consequences were disregarded. This practice is less applicable since the society is less willing to bear the costs and consequences of externalities for various reasons (public awareness, quality of life considerations, high health costs, etc.).
5. Assessing Environmental Externalities
Air pollution is the most important source of environmental externalities for transportation. Although the nature of air pollutants is clearly identified, the scale and scope on how they influence the biosphere are subject to much controversy. On the positive side, emissions of the most harmful air pollutants, such as Carbon Monoxide and Volatile Organic Compounds, have declined in spite of a substantial growth in the number of vehicles an indication of growing levels of environmental compliance of vehicles. Carbon Dioxide emissions have increased proportionally with the growth of transportation usage. Air pollution costs are probably the most extensive of all environmental externalities of transportation, mainly because the atmosphere enables a fast and widespread diffusion of pollutants.
As all externalities, costs are very difficult to evaluate because several consequences are not understood, the problems could be at another scale or highly correlated with others and/or a value (monetary or other) cannot be effectively attributed. Two major groups of factors are contributing to air pollution, notably in urban areas.
- Structural factors are essentially linked to the size and level of consumption of an economy. Factors such and income and education tend to be proportional with emissions.
- Behavioral factors are linked to individualism, consumerism and transportation preferences. Because of convenience and its symbolism, the car is systematically the preferred mode of transportation, even when other modes are available.
From a general perspective, the costs of air pollution associated with transportation can be grouped within economic,social and environmental costs. Externalities related to water pollution are almost all indirect consequences. It is thus difficult to evaluate and to appraise the specific contribution of transportation over various environmental issues, which explains that problems tend to be addressed on a modal basis.
Noise emissions can be represented as point (a vehicle), line (a highway) and surface (ambient noise generated by a set of streets) sources. Noise pollution is only present as vibrations. For instance, for a road vehicle, vibrations are created through the internal combustion engine, moving parts (transmission) and friction on the surface over which a transport mode moves. The impacts of noise is strictly local, as vibrations are quickly attenuated by the distance and the nature of the landscape (trees, hills, etc.).
A hazardous material is a substance capable of posing an unreasonable risk to health, safety, and property when transported in commerce. Considering the large amounts of freight being shipped through transport systems, hazardous materials have become a concern. Several hazardous materials (hazmat) releases are spectacular events, notably when it involves a supertanker or a train convoy. However, we must consider that maritime transportation only accounts for 0.1% of the total number of hazmat accidents in the United States, although the volume of hazmat released is higher. Other transportation modes are thus important sources of hazmat release in the environment, even if they mostly involve small quantities. Very limited information is available on the nature and consequences of hazmats released during transportation, except for safety regulations. The effects of hazmat release are always punctual, but intense. The nature of the effect is related to the type of accident and the hazmat involved. It can range from a small scale accident where limited quantities of hazmat are spilled, to important accidents requiring prompt intervention and evacuation of population.
Thus, transportation has a wide array of environmental externalities, some of which can be reasonably assessed while others are mostly speculation (often taken as facts by environmentalist groups). Externalities are also occurring at different geographical scales, and some may even overlap over several. The bottom line is that better transport practices, such a fuel efficient vehicles, that reduce environmental externalities are likely to have positive economic, social and environmental consequences. The matter remains about which strategy is the most beneficial as in all environmental matters much subjectivity and often ideology prevails.
For other uses, see Transport (disambiguation).
"Transportation" redirects here. For other uses, see Transportation (disambiguation).
Transport or transportation is the movement of humans, animals and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline and space. The field can be divided into infrastructure, vehicles and operations. Transport is important because it enables trade between people, which is essential for the development of civilizations.
Transport infrastructure consists of the fixed installations including roads, railways, airways, waterways, canals and pipelines and terminals such as airports, railway stations, bus stations, warehouses, trucking terminals, refueling depots (including fueling docks and fuel stations) and seaports. Terminals may be used both for interchange of passengers and cargo and for maintenance.
Vehicles traveling on these networks may include automobiles, bicycles, buses, trains, trucks, people, helicopters, watercraft, spacecraft and aircraft.
Operations deal with the way the vehicles are operated, and the procedures set for this purpose including financing, legalities, and policies. In the transport industry, operations and ownership of infrastructure can be either public or private, depending on the country and mode.
Passenger transport may be public, where operators provide scheduled services, or private. Freight transport has become focused on containerization, although bulk transport is used for large volumes of durable items. Transport plays an important part in economic growth and globalization, but most types cause air pollution and use large amounts of land. While it is heavily subsidized by governments, good planning of transport is essential to make traffic flow and restrain urban sprawl.
Main article: History of transport
Humans' first means of transport involved walking, running and swimming. The domestication of animals introduced a new way to lay the burden of transport on more powerful creatures, allowing the hauling of heavier loads, or humans riding animals for greater speed and duration. Inventions such as the wheel and the sled helped make animal transport more efficient through the introduction of vehicles. Water transport, including rowed and sailed vessels, dates back to time immemorial, and was the only efficient way to transport large quantities or over large distances prior to the Industrial Revolution.
The first forms of road transport involved animals, such as horses (domesticated in the 4th or 3rd millennium BCE), oxen (from about 8000 BCE) or humans carrying goods over dirt tracks that often followed gametrails. Many early civilizations, including Mesopotamia and the Indus Valley Civilization, constructed paved roads. In classical antiquity, the Persian and Roman empires built stone-paved roads to allow armies to travel quickly. Deep roadbeds of crushed stone underneath kept such roads dry. The medieval Caliphate later built tar-paved roads. The first watercraft were canoes cut out from tree trunks. Early water transport was accomplished with ships that were either rowed or used the wind for propulsion, or a combination of the two. The importance of water has led to most cities that grew up as sites for trading being located on rivers or on the sea-shore, often at the intersection of two bodies of water. Until the Industrial Revolution, transport remained slow and costly, and production and consumption gravitated as close to each other as feasible.
The Industrial Revolution in the 19th century saw a number of inventions fundamentally change transport. With telegraphy, communication became instant and independent of the transport of physical objects. The invention of the steam engine, closely followed by its application in rail transport, made land transport independent of human or animal muscles. Both speed and capacity increased rapidly, allowing specialization through manufacturing being located independently of natural resources. The 19th century also saw the development of the steam ship, which sped up global transport.
With the development of the combustion engine and the automobile around 1900, road transport became more competitive again, and mechanical private transport originated. The first "modern" highways were constructed during the 19th century with macadam. Later, tarmac and concrete became the dominant paving materials. In 1903 the Wright brothers demonstrated the first successful controllable airplane, and after World War I (1914–1918) aircraft became a fast way to transport people and express goods over long distances.
After World War II (1939–1945) the automobile and airlines took higher shares of transport, reducing rail and water to freight and short-haul passenger services. Scientific spaceflight began in the 1950s, with rapid growth until the 1970s, when interest dwindled. In the 1950s the introduction of containerization gave massive efficiency gains in freight transport, fostering globalization. International air travel became much more accessible in the 1960s with the commercialization of the jet engine. Along with the growth in automobiles and motorways, rail and water transport declined in relative importance. After the introduction of the Shinkansen in Japan in 1964, high-speed rail in Asia and Europe started attracting passengers on long-haul routes away from airlines.
Early in U.S. history,[when?]privatejoint-stockcorporations owned most aqueducts, bridges, canals, railroads, roads, and tunnels. Most such transportation infrastructure came under government control in the late 19th and early 20th centuries, culminating in the nationalization of inter-city passenger rail-service with the establishment of Amtrak. Recently,[when?] however, a movement to privatize roads and other infrastructure has gained some[quantify] ground and adherents.
Further information: Timeline of transportation technology
Main article: Mode of transport
A mode of transport is a solution that makes use of a particular type of vehicle, infrastructure, and operation. The transport of a person or of cargo may involve one mode or several of the modes, with the latter case being called intermodal or multimodal transport. Each mode has its own advantages and disadvantages, and will be chosen for a trip on the basis of cost, capability, and route.
Main article: Human-powered transport
Human powered transport, a form of sustainable transportation, is the transport of people and/or goods using human muscle-power, in the form of walking, running and swimming. Modern technology has allowed machines to enhance human power. Human-powered transport remains popular for reasons of cost-saving, leisure, physical exercise, and environmentalism; it is sometimes the only type available, especially in underdeveloped or inaccessible regions.
Although humans are able to walk without infrastructure, the transport can be enhanced through the use of roads, especially when using the human power with vehicles, such as bicycles and inline skates. Human-powered vehicles have also been developed for difficult environments, such as snow and water, by watercraft rowing and skiing; even the air can be entered with human-powered aircraft.
Main article: Animal-powered transport
Animal-powered transport is the use of working animals for the movement of people and commodities. Humans may ride some of the animals directly, use them as pack animals for carrying goods, or harness them, alone or in teams, to pull sleds or wheeled vehicles.
Main article: Aviation
A fixed-wing aircraft, commonly called airplane, is a heavier-than-air craft where movement of the air in relation to the wings is used to generate lift. The term is used to distinguish this from rotary-wing aircraft, where the movement of the lift surfaces relative to the air generates lift. A gyroplane is both fixed-wing and rotary wing. Fixed-wing aircraft range from small trainers and recreational aircraft to large airliners and military cargo aircraft.
Two things necessary for aircraft are air flow over the wings for lift and an area for landing. The majority of aircraft also need an airport with the infrastructure to receive maintenance, restocking, refueling and for the loading and unloading of crew, cargo, and passengers. While the vast majority of aircraft land and take off on land, some are capable of take-off and landing on ice, snow, and calm water.
The aircraft is the second fastest method of transport, after the rocket. Commercial jets can reach up to 955 kilometres per hour (593 mph), single-engine aircraft 555 kilometres per hour (345 mph). Aviation is able to quickly transport people and limited amounts of cargo over longer distances, but incurs high costs and energy use; for short distances or in inaccessible places helicopters can be used. As of April 28, 2009, The Guardian article notes that, "the WHO estimates that up to 500,000 people are on planes at any time."
Main article: Ground transportation
Land transport covers all land-based transportation systems that provide for the movement of people, goods and services. Land transport plays a vital role in linking communities to each other. Land transport is a key factor in urban planning. It consists of 2 kinds, rail and road.
Main article: Rail transport
Rail transport is where a train runs along a set of two parallel steelrails, known as a railway or railroad. The rails are anchored perpendicular to ties (or sleepers) of timber, concrete or steel, to maintain a consistent distance apart, or gauge. The rails and perpendicular beams are placed on a foundation made of concrete or compressed earth and gravel in a bed of ballast. Alternative methods include monorail and maglev.
A train consists of one or more connected vehicles that operate on the rails. Propulsion is commonly provided by a locomotive, that hauls a series of unpowered cars, that can carry passengers or freight. The locomotive can be powered by steam, diesel or by electricity supplied by trackside systems. Alternatively, some or all the cars can be powered, known as a multiple unit. Also, a train can be powered by horses, cables, gravity, pneumatics and gas turbines. Railed vehicles move with much less friction than rubber tires on paved roads, making trains more energy efficient, though not as efficient as ships.
Intercity trains are long-haul services connecting cities; modern high-speed rail is capable of speeds up to 350 km/h (220 mph), but this requires specially built track. Regional and commuter trains feed cities from suburbs and surrounding areas, while intra-urban transport is performed by high-capacity tramways and rapid transits, often making up the backbone of a city's public transport. Freight trains traditionally used box cars, requiring manual loading and unloading of the cargo. Since the 1960s, container trains have become the dominant solution for general freight, while large quantities of bulk are transported by dedicated trains.
Main article: Road transport
A road is an identifiable route, way or path between two or more places. Roads are typically smoothed, paved, or otherwise prepared to allow easy travel; though they need not be, and historically many roads were simply recognizable routes without any formal construction or maintenance. In urban areas, roads may pass through a city or village and be named as streets, serving a dual function as urban space easement and route.
The most common road vehicle is the automobile; a wheeled passenger vehicle that carries its own motor. Other users of roads include buses, trucks, motorcycles, bicycles and pedestrians. As of 2010, there were 1.015 billion automobiles worldwide. Road transport offers a complete freedom to road users to transfer the vehicle from one lane to the other and from one road to another according to the need and convenience. This flexibility of changes in location, direction, speed, and timings of travel is not available to other modes of transport. It is possible to provide door to door service only by road transport.
Automobiles provide high flexibility with low capacity, but require high energy and area use, and are the main source of noise and air pollution in cities; buses allow for more efficient travel at the cost of reduced flexibility. Road transport by truck is often the initial and final stage of freight transport.
Main article: Ship transport
Water transport is movement by means of a watercraft—such as a barge, boat, ship or sailboat—over a body of water, such as a sea, ocean, lake, canal or river. The need for buoyancy is common to watercraft, making the hull a dominant aspect of its construction, maintenance and appearance.
In the 19th century, the first steam ships were developed, using a steam engine to drive a paddle wheel or propeller to move the ship. The steam was produced in a boiler using wood or coal and fed through a steam external combustion engine. Now most ships have an internal combustion engine using a slightly refined type of petroleum called bunker fuel. Some ships, such as submarines, use nuclear power to produce the steam. Recreational or educational craft still use wind power, while some smaller craft use internal combustion engines to drive one or more propellers, or in the case of jet boats, an inboard water jet. In shallow draft areas, hovercraft are propelled by large pusher-prop fans. (See Marine propulsion.)
Although it is slow compared to other transportation, modern sea transport is a highly efficient method of transporting large quantities of goods. Commercial vessels, nearly 35,000 in number, carried 7.4 billion tons of cargo in 2007. Transport by water is significantly less costly than air transport for transcontinental shipping;short sea shipping and ferries remain viable in coastal areas.
Pipeline transport sends goods through a pipe; most commonly liquid and gases are sent, but pneumatic tubes can also send solid capsules using compressed air. For liquids/gases, any chemically stable liquid or gas can be sent through a pipeline. Short-distance systems exist for sewage, slurry, water and beer, while long-distance networks are used for petroleum and natural gas.
Cable transport is a broad mode where vehicles are pulled by cables instead of an internal power source. It is most commonly used at steep gradient. Typical solutions include aerial tramway, elevators, escalator and ski lifts; some of these are also categorized as conveyor transport.
Spaceflight is transport out of Earth's atmosphere into outer space by means of a spacecraft. While large amounts of research have gone into technology, it is rarely used except to put satellites into orbit, and conduct scientific experiments. However, man has landed on the moon, and probes have been sent to all the planets of the Solar System.
Suborbital spaceflight is the fastest of the existing and planned transport systems from a place on Earth to a distant "other place" on Earth. Faster transport could be achieved through part of a low Earth orbit, or following that trajectory even faster using the propulsion of the rocket to steer it.
Main article: Infrastructure
Infrastructure is the fixed installations that allow a vehicle to operate. It consists of a roadway, a terminal, and facilities for parking and maintenance. For rail, pipeline, road and cable transport, the entire way the vehicle travels must be constructed. Air and watercraft are able to avoid this, since the airway and seaway do not need to be constructed. However, they require fixed infrastructure at terminals.
Terminals such as airports, ports, and stations, are locations where passengers and freight can be transferred from one vehicle or mode to another. For passenger transport, terminals are integrating different modes to allow riders, who are interchanging between modes, to take advantage of each mode's benefits. For instance, airport rail links connect airports to the city centers and suburbs. The terminals for automobiles are parking lots, while buses and coaches can operate from simple stops. For freight, terminals act as transshipment points, though some cargo is transported directly from the point of production to the point of use.
The financing of infrastructure can either be public or private. Transport is often a natural monopoly and a necessity for the public; roads, and in some countries railways and airports are funded through taxation. New infrastructure projects can have high costs and are often financed through debt. Many infrastructure owners, therefore, impose usage fees, such as landing fees at airports, or toll plazas on roads. Independent of this, authorities may impose taxes on the purchase or use of vehicles. Because of poor forecasting and overestimation of passenger numbers by planners, there is frequently a benefits shortfall for transport infrastructure projects.
Main article: Vehicle
A vehicle is a non-living device that is used to move people and goods. Unlike the infrastructure, the vehicle moves along with the cargo and riders. Unless being pulled/pushed by a cable or muscle-power, the vehicle must provide its own propulsion; this is most commonly done through a steam engine, combustion engine, electric motor, a jet engine or a rocket, though other means of propulsion also exist. Vehicles also need a system of converting the energy into movement; this is most commonly done through wheels, propellers and pressure.
Vehicles are most commonly staffed by a driver. However, some systems, such as people movers and some rapid transits, are fully automated. For passenger transport, the vehicle must have a compartment, seat, or platform for the passengers. Simple vehicles, such as automobiles, bicycles or simple aircraft, may have one of the passengers as a driver.
Private transport is only subject to the owner of the vehicle, who operates the vehicle themselves. For public transport and freight transport, operations are done through private enterprise or by governments. The infrastructure and vehicles may be owned and operated by the same company, or they may be operated by different entities. Traditionally, many countries have had a national airline and national railway. Since the 1980s, many of these have been privatized. International shipping remains a highly competitive industry with little regulation, but ports can be public-owned.
Relocation of travelers and cargo are the most common uses of transport. However, other uses exist, such as the strategic and tactical relocation of armed forces during warfare, or the civilian mobility construction or emergency equipment.
Main articles: Travel and Public transit
Passenger transport, or travel, is divided into public and private transport. Public transport is scheduled services on fixed routes, while private is vehicles that provide ad hoc services at the riders desire. The latter offers better flexibility, but has lower capacity, and a higher environmental impact. Travel may be as part of daily commuting, for business, leisure or migration.
Short-haul transport is dominated by the automobile and mass transit. The latter consists of buses in rural and small cities, supplemented with commuter rail, trams and rapid transit in larger cities. Long-haul transport involves the use of the automobile, trains, coaches and aircraft, the last of which have become predominantly used for the longest, including intercontinental, travel. Intermodal passenger transport is where a journey is performed through the use of several modes of transport; since all human transport normally starts and ends with walking, all passenger transport can be considered intermodal. Public transport may also involve the intermediate change of vehicle, within or across modes, at a transport hub, such as a bus or railway station.
Taxis and buses can be found on both ends of the public transport spectrum. Buses are the cheaper mode of transport but are not necessarily flexible, and taxis are very flexible but more expensive. In the middle is demand-responsive transport, offering flexibility whilst remaining affordable.
International travel may be restricted for some individuals due to legislation and visa requirements.
An ambulance is a vehicle used to transport people from or between places of treatment, and in some instances will also provide out-of-hospital medical care to the patient. The word is often associated with road-going "emergency ambulances", which form part of emergency medical services, administering emergency care to those with acute medical problems.
Air medical services is a comprehensive term covering the use of air transportation to move patients to and from healthcare facilities and accident scenes. Personnel provide comprehensive prehospital and emergency and critical care to all types of patients during aeromedical evacuation or rescue operations, aboard helicopters, propeller aircraft, or jet aircraft.
Main article: Shipping
Freight transport, or shipping, is a key in the value chain in manufacturing. With increased specialization and globalization, production is being located further away from consumption, rapidly increasing the demand for transport. Transportation creates place utility by moving the goods from the place of production to the place of consumption. While all modes of transport are used for cargo transport, there is high differentiation between the nature of the cargo transport, in which mode is chosen.Logistics refers to the entire process of transferring products from producer to consumer, including storage, transport, transshipment, warehousing, material-handling, and packaging, with associated exchange of information.Incoterm deals with the handling of payment and responsibility of risk during transport.
Containerization, with the standardization of ISO containers on all vehicles and at all ports, has revolutionized international and domestic trade, offering huge reduction in transshipment costs. Traditionally, all cargo had to be manually loaded and unloaded into the haul of any ship or car; containerization allows for automated handling and transfer between modes, and the standardized sizes allow for gains in economy of scale in vehicle operation. This has been one of the key driving factors in international trade and globalization since the 1950s.
Bulk transport is common with cargo that can be handled roughly without deterioration; typical examples are ore, coal, cereals and petroleum. Because of the uniformity of the product, mechanical handling can allow enormous quantities to be handled quickly and efficiently. The low value of the cargo combined with high volume also means that economies of scale become essential in transport, and gigantic ships and whole trains are commonly used to transport bulk. Liquid products with sufficient volume may also be transported by pipeline.
Air freight has become more common for products of high value; while less than one percent of world transport by volume is by airline, it amounts to forty percent of the value. Time has become especially important in regards to principles such as postponement and just-in-time within the value chain, resulting in a high willingness to pay for quick delivery of key components or items of high value-to-weight ratio. In addition to mail, common items sent by air include electronics and fashion clothing.
Main article: Sustainable transport
Main article: Transport economics
Transport is a key necessity for specialization—allowing production and consumption of products to occur at different locations. Transport has throughout history been a spur to expansion; better transport allows more trade and a greater spread of people. Economic growth has always been dependent on increasing the capacity and rationality of transport. But the infrastructure and operation of transport has a great impact on the land and is the largest drainer of energy, making transport sustainability a major issue.
Due to the way modern cities and communities are planned and operated, a physical distinction between home and work is usually created, forcing people to transport themselves to places of work, study, or leisure, as well as to temporarily relocate for other daily activities. Passenger transport is also the essence of tourism, a major part of recreational transport. Commerce requires the transport of people to conduct business, either to allow face-to-face communication for important decisions or to move specialists from their regular place of work to sites where they are needed.
Main article: Transport planning
Transport planning allows for high utilization and less impact regarding new infrastructure. Using models of transport forecasting, planners are able to predict future transport patterns. On the operative level, logistics allows owners of cargo to plan transport as part of the supply chain. Transport as a field is also studied through transport economics, a component for the creation of regulation policy by authorities. Transport engineering, a sub-discipline of civil engineering, must take into account trip generation, trip distribution, mode choice and route assignment, while the operative level is handled through traffic engineering.
Because of the negative impacts incurred, transport often becomes the subject of controversy related to choice of mode, as well as increased capacity. Automotive transport can be seen as a tragedy of the commons, where the flexibility and comfort for the individual deteriorate the natural and urban environment for all. Density of development depends on mode of transport, with public transport allowing for better spatial utilization. Good land use keeps common activities close to people's homes and places higher-density development closer to transport lines and hubs, to minimize the need for transport. There are economies of agglomeration. Beyond transportation some land uses are more efficient when clustered. Transportation facilities consume land, and in cities, pavement (devoted to streets and parking) can easily exceed 20 percent of the total land use. An efficient transport system can reduce land waste.
Too much infrastructure and too much smoothing for maximum vehicle throughput means that in many cities there is too much traffic and many—if not all—of the negative impacts that come with it. It is only in recent years that traditional practices have started to be questioned in many places, and as a result of new types of analysis which bring in a much broader range of skills than those traditionally relied on—spanning such areas as environmental impact analysis, public health, sociologists as well as economists—the viability of the old mobility solutions is increasingly being questioned.
Main article: Transport and the environment
Transport is a major use of energy and burns most of the world's petroleum. This creates air pollution, including nitrous oxides and particulates, and is a significant contributor to global warming through emission of carbon dioxide, for which transport is the fastest-growing emission sector. By subsector, road transport is the largest contributor to global warming.Environmental regulations in developed countries have reduced individual vehicles' emissions; however, this has been offset by increases in the numbers of vehicles and in the use of each vehicle. Some pathways to reduce the carbon emissions of road vehicles considerably have been studied. Energy use and emissions vary largely between modes, causing environmentalists to call for a transition from air and road to rail and human-powered transport, as well as increased transport electrification and energy efficiency.
Other environmental impacts of transport systems include traffic congestion and automobile-oriented urban sprawl, which can consume natural habitat and agricultural lands. By reducing transportation emissions globally, it is predicted that there will be significant positive effects on Earth's air quality, acid rain, smog and climate change.
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