The Geography of Transport Systems
Jean-Paul Rodrigue (2017), New York: Routledge, 440 pages.
ISBN 978-1138669574
Road Transportation
Authors: Dr. Jean-Paul Rodrigue and Dr. Brian Slack
1. The Setting of Road Transport Systems
Two major modes are composing the land transport system, roads and railways. Obviously, roads were established first, as rail technology only became available by the 18th century, in the midst on the industrial revolution. Historical considerations are important in assessing the structure of current land transportation networks. Modern roads tend to follow the structure established by previous roads, as it was the case for the modern European road network (especially in Italy, France and Britain) that follows the structure established by the Roman road network centuries before.
The first land roads took their origins from trails which were generally used to move from one hunting territory to another. With the emergence of the first forms of nation-states trails started to be used for commercial purposes as trade expanded and some became roads, especially through the domestication of animals such as horses, mules and camels. The use of wheeled vehicles encouraged construction of better roads to support the additional weight. However, a road transport system requires a level of labor organization and administrative control that could only be provided by a form of governmental oversight offering some military protection over trade routes. By 3,000 BC the first paved road systems appeared in Mesopotamia and asphalt was used to pave roads in Babylon by 625 BC. The Persian Empire had a road of 2,300 km in the 5th century BC. However, the first major road system was established by the Roman Empire from 300 BC and onwards, mainly for economic, military and administrative reasons. It relied on solid road engineering methods, including the laying of foundations and the construction of bridges. This was also linked with the establishment of pan-continental trading routes, such as the Silk Road, linking Europe and Asia by 100 BC.
Following the fall of the Roman Empire in the 5th century, integrated road transportation fell out of favor as most roads were locally constructed and maintained. Because of the lack of maintenance of many road segments, land transport became a very hazardous activity. It is not until the creation of modern nation-states in the 17th century that national road transportation systems were formally established. In the 18th century, the French, through central government efforts, build their Royal Roads system spanning 24,000 km, over which a public transport service of stage-coaches carrying passengers and mail was established. The British, mainly through private efforts, built a 32,000 km system of turnpikes where tolls have to be paid for road usage. A similar initiative was undertaken in the United States in the 19th century and by the early 20th century, a network of 3 million km of roads, most unpaved, was in operation. 1794 marks the beginning of modern road transportation with the first mail coach service between London and Bristol, operating under a timetable.
Also of high significance were technological innovations in road engineering that permitted the construction of reliable and low cost hard surface roads. One such achievement came from the Scottish engineer McAdam who developed a process (later known as macadam) where hard and waterproof road surfaces were made by cemented crushed stone, bound together either with water or with bitumen. It provided a cheaper, durable, smooth and non-slippery pavement, which considerably improved the reliability and the travel speed on roads. Many roads could now be used year round.
Road development accelerated in the first half of the 20th century. By the 1920s, the first all-weather transcontinental highway, the Lincoln Highway, spanned over 5,300 km between New York and San Francisco. However, it was simply a set of connected roads. Germany was the first to build the modern highway (autobahn) in 1932 with specifications such as restricted access, overpasses and road separation that would eventually become common characteristics of modern highway systems. The post-World War Two era represented a period of rapid expansion of road transportation networks worldwide.
The most remarkable road transport achievement is without doubt the setting of the American Interstate highway system initiated in 1956. Its strategic purpose was to provide a national road system servicing the American economy and also able to support troop movements and act as air strips in case of an emergency. About 56,000 km were built from the 1950s to the 1970s, but between 1975 and 2006 only 15,000 km were added to the system, underlining growing construction costs and diminishing returns. Overall, about 70,000 km of four-lane and six-lane highways were constructed, linking all major American cities, coast to coast. A similar project took place in Canada with the Trans-Canada highway completed in 1962. By the 1970s, every modern nation has constructed a national highway system, which in the case of Western Europe resulted in a pan-European system. This trend now takes place in many industrializing countries. For instance, China is building a national highway system that expanded to 104,000 km in 2013, with construction taking place at a pace of about 2,000 km per year.
2. The Spatial Impacts of Road Transportation
Road transportation is the mode that has expanded the most over the last 50 years, both for passengers and freight transportation. This represents a dramatic change in the built environment with the massive addition of road infrastructures. The spatial cover of road transportation is extensive. Growth in road freight transport has been fueled largely by trade liberalization as modal shares of trade within the European Union and NAFTA suggest. This is the result of growth of the loading capacity of vehicle and an adaptation of vehicle to freight (e.g. perishables, fuel, construction materials, etc.) or passengers (e.g. school bus) demand for speed, autonomy and flexibility. Problems, such as a significant growth of fuel consumption, increasing environmental externalities, traffic congestion and a safety (accidents) have also emerged.
Roads have a functional hierarchy depending on the role they play in the network. At the top of the hierarchy are freeways (highways), which are limited access roads with no intersections. There are also arterials that are roads that have traffic signals at intersection, forcing vehicles to stop. These arterials are fed by collectors and local roads, which have the main purpose to connect specific activities (residences, retail stores, industries). Put together, this network enables point to point services, a notable advantage the road transport has over other transport modes. Road transport modes have limited potential to achieve economies of scale. This is due to size and weight constraints imposed by governments and also by the technical and economic limits of engines. In most jurisdictions, trucks and busses have specific weight and length restrictions which are imposed for safety reasons. While in the United States, the maximum gross vehicle weight is 36 metric tons (80,000 pounds), while in Europe and China these figures are 40 (88,000 pounds) and 49 (100,000 pounds) metric tons respectively. In addition, there are serious limits on the traction capacities of cars, buses and trucks because of the considerable growth in energy consumption that accompany increases in the vehicle weight. For these reasons the carrying capacities of individual road vehicles are limited.
Road transportation is characterized by acute geographical disparities in traffic. It is not uncommon that 20% of the road network supports 60 to 80% of the traffic. This observation is expanded by the fact that developed and developing countries have important differences in terms of the density, capacity and the quality of road transport infrastructures. Acute geographical variations of the inventory are therefore the norm.
Technological evolution of road transport vehicles was a continuous trend since the first automobiles were built. The basic technology is however very similar, as road transportation massively relies on the internal combustion engine. In the future new materials (ceramic, plastic, aluminum, composite materials etc...), fuels (electricity, hydrogen, natural gas, etc...) and information technologies (vehicle control, location, navigation and toll collection) are expected to be included in cars and improve the efficiency of road transport systems. There are however signs that a peak mobility can be achieved for road transportation when the car has been diffused to some optimum level and that countervailing forces are at play such as congestion, the aging of the population or a decline in income. A similar pattern of peaking truck circulation is emerging in large metropolitan areas.
The urban population has increased considerably over the last 50 years and about 50% of the global population was urbanized by 2010 (about 3.5 billion people). It is challenging for developing countries to have a rates of individual vehicle ownership similar to those of developed countries, especially compared with the United States, not because of a lack of income, but the physical lack of space to accommodate a high level of car ownership. This will impose new or alternative methods to transport freight and passengers over urban roads. The reduction of vehicle emissions and the impacts of infrastructures on the environment are mandatory to promote a sustainable environment. Under such circumstances cycling is thus to be considered an alternative to the automobile in urban areas, widely adopted in developing countries, although more for economic reasons. However, the potential of cycling is related to its substitution for existing public transit users. There is limited potential to substitute car trips by bicycle trips since most car trips cover longer distances that are not easily substitutable by other modes, including the bicycle. Bicycle parking schemes at urban transit stations are a strategy that can be used as a strategy to incite a substitution.
Road transport, however, possesses significant advantages over other modes:
  • The capital cost of vehicles is relatively small, which makes it comparatively easy for new users to gain entry. This helps ensure that the trucking industry, for example, is highly competitive. Low capital costs also ensure that innovations and new technologies can diffuse quickly through the industry.
  • Another advantage of road transport is the high relative speed of vehicles, the major constraint being government-imposed speed limits.
  • One of its most important attributes is the flexibility of route choice, once a network of roads is provided. Road transport has the unique opportunity of providing door to door service for both passengers and freight.
These multiple advantages have made cars, buses and trucks the modes of choice for a large number of trip purposes, and have led to their market dominance for short distance trips. The success of cars and trucks has given rise to a number of serious problems. Road congestion has become a feature of most urban areas around the world. In addition, the mode is behind many of the major environmental externalities linked to transportation. Addressing these issues is becoming an important policy challenge at all levels of jurisdiction, from the local to the global. A symbiosis between types of roads and types of traffic with specialization (reserved lanes and hours) is to be expected.
3. Infrastructures and Investments
Road infrastructures are moderately expensive to provide, but there is a wide divergence of costs, from a gravel road to a multi-lane urban expressway. Because vehicles have the means to climb moderate slopes, physical obstacles are less important than for some other land modes, namely rail. Most roads are provided as a public good by governments, while the vast majority of vehicles are owned privately. Capital costs, therefore, are generally assumed by the society, and do not fall as heavily on one source as is the case for other modes. Unlike many transport infrastructures where the network is paid for by the user through a pricing mechanism, 95% of the financing of road infrastructure is covered by the public sector, leaving the reminder covered by tolls. Road transportation thus has a unique characteristic where several costs are externalized. This is an indirect form of mobility subsidy.
The public offering of free road infrastructure conveys several advantages to the private sector, but can also lead to serious problems. The main advantage is clear; the users of roads commonly do not bear the full operating costs implying that road transportation tends to be below real market price. For road freight transportation, this can be seen as a subsidy as road maintenance is not part of the operating costs, but is indirectly present with taxes and tolls. As long as there is spare road capacity this situation works for the benefit of the users. However, when congestion starts to arise, users have limited, if any, influence on the construction of new and improved infrastructure to mitigate the problem since they do not own the infrastructure and are using it for free. Lobbying public entities to receive public road infrastructure investments can be a very long process, subject to constant delays and changes. Road users thus become trapped in a situation they can do little to change since it is provided free of charge. This can be labeled as the "free roads curse". An entity owning and operating its own network, such as a rail company in North America, has the advantage of directly implementing improvements with its own capital if congestion arise on a segment of its network. It is thus better placed to cope with congestion.
Governments can expropriate the necessary land for road construction since a private enterprise may have difficulties to expropriate without government support. Another important aspect about roads is their economies of scale and their indivisibility, underlining that the construction and maintenance of roads is cheaper when the system is extensive, but to a limit. However, all road transport modes have limited abilities to achieve scale economies. This is due to the size constraints imposed by governments and also by the technical and economic limits of the power sources and what infrastructures can bear weight-wise. In most jurisdictions, trucks and busses have specific weight and length restrictions which are imposed for safety reasons. In addition, there are serious limits on the traction capacities of cars, busses and trucks because of the considerable increases in energy consumption that accompany increases in the weight of the unit. For these reasons the carrying capacities of individual road vehicles are limited. Roads are thus costly infrastructures, but also sources of revenue:
  • Costs. They include rights of way, development costs (planning), construction costs, maintenance and administration costs, losses in land taxes (urban environment), expropriation costs (money and time), and external costs (accidents and pollution).
  • Revenue. They include registration, gas (taxes), purchases of vehicles (taxes), tolls, parking, and insurance fees. Another form of indirect income concerns traffic violations (e.g. speeding) that are using the pretext of public safety to hide revenue generation practices by local governments.
In many cases governments have been inefficient custodians of road infrastructure as it is tempting to delay road maintenance or improvements because of the high costs involved. Budgetary problems are also inciting selling assets to increase revenue and reduce expenses. Consequently, a growing number of roads have been privatized and companies specializing in road management have emerged, particularly in Europe and North America. This is only possible on specific trunks that have an important and stable traffic. Private enterprises usually have vested interests to see that the road segments they manage are maintained and improved since the quality of the road will be directly linked with revenue generation. The majority of toll roads are highways linking large cities or bridges and tunnels where there is a convergence of traffic. Most roads are not economically profitable but must be socially present as they are essential to service populations. It can thus be expected that roads will remain dominantly publically funded in the future.