The Geography of Transport Systems
FOURTH EDITION
Jean-Paul Rodrigue (2017), New York: Routledge, 440 pages.
ISBN 978-1138669574
Transport and Sustainability
Authors: Dr. Jean-Paul Rodrigue
1. Sustainable Development
An issue that has triggered concerns over the recent decades relates to the capacity of the global economy to accommodate an enduring demographic, economic and resource consumption growth. Since the 1970s, many statements have been made asserting that the world would be unable to sustain such growth without a possible socioeconomic and environmental breakdown. While these perspectives have been demonstrated to be inaccurate, since resources availability and the quality of life increased, there are enduring concerns that at some point a threshold will be reached, particularly in regard to climate change. Under such conditions, an emphasis on sustainable development has been advocated as a priority for future social and economic development.
Sustainable development is however a complex concept that is subject to numerous interpretations since it involves interdisciplinary and numerous interconnections. It is not surprising that the subject is prone to confusion in terms of its nature, consequences and appropriate response. It is however generally agreed that a sustainable society favors conditions that benefits the environment, the economy and the society without compromising the welfare of future generations. Still, as history clearly demonstrates, the conditions of future societies will largely depend upon the legacy of current societies on resources and the environment. All forms of assets (capital, real estate, infrastructures, resources) passed on to the next generation should be at least of equal value (utility) per capita. The basic definition of sustainability has been expanded to include three major points (often referred as the three Es):
  • Social equity. Relates to conditions favoring a distribution of resources among the current generation based upon comparative levels of productivity. This implies that individuals or institutions are free to pursue the ventures of their choice and reaps the rewards for the risk they take and the efforts they make. Social equity is usually the most difficult element of the concept of sustainability to define. It should not be confused with redistribution where a segment of the population agrees or is coerced to support another segment.
  • Economic efficiency. Concerns conditions permitting higher levels of economic efficiency in terms of resource and labor usage. It focuses on capabilities, competitiveness, flexibility in production and providing goods and services that supply a market demand. Under such circumstances, factors of production should be freely allocated and markets open to trade.
  • Environmental responsibility. Involves a "footprint" which is lesser than the capacity of the environment to accommodate. This includes the supply of resources (food, water, energy, etc.), but also the safe disposal of numerous forms of wastes. Its core tenets include the conservation and reuse of products and resources.
Another important debate relates to what extent public entities (both at the national and supra-national levels) have a role to play. More bluntly, should sustainability be imposed by regulation or be the outcome of market forces? Environmentalists are dominantly leaning towards regulations and would argue that sustainability is a much too long term concept to be addressed by corporations focused on the short term. A counter argument could be made that the time horizon of governments, especially democratic regimes, is also very short and on rare instances governments have shown to be proactive regarding environmental matters. The question remains as if expectations can be placed on entities that seek to optimize positive perception (governments) or on entities that seek to optimize efficiency (corporations). Paradoxically, while governments tend to be inflexible and unable to adapt, corporations have demonstrated a resounding ability to shift their strategies and provide products that reflect the needs of their customers (including environmentally responsible products). It could thus be argued that the private sector is more likely to achieve sustainability than the public sector.
Societies do not contribute to environmental problems at the same level. Sustainability can be thus expressed at two spatial levels:
  • Global. Long term stability of the earth’s environment and availability of resources to support human activities.
  • Local. Localized forms often related to urban areas in terms of jobs, housing and environmental pollution.
Since a growing share of the global population is urbanized, sustainability has increasingly become focused on urban areas. Major cities are requiring a vast array of supporting infrastructures including energy, water, sewers and transport. A key to urban sustainability issues is linked with the provision and maintenance of a wide range of urban infrastructure. Every city has specific infrastructure and environmental problems. For instance, many cities in developing countries have chronic deficiencies in the provision of the most basic infrastructure while their environmental conditions are deteriorating.
Infrastructures can be publicly or privately owned. Public infrastructures have the advantage to be available to a larger share of the population at a low cost, but are expensive for the government to maintain (subsidies). Private infrastructures tend to service a smaller share of the population, at the choice of the infrastructure company, but are financially profitable. As income levels increase, some infrastructure problems are solved while some environmental problems are created. For instance, an increase in income is linked to better sanitation and water provision, but at the expense of greater waste and carbon dioxide emissions.
2. Sustainable Transportation
Transportation, as a core component supporting the interactions and the development of socioeconomic systems, has also been the object of much consideration about to what extent it is sustainable. Sustainable transportation can be defined as the capacity to support the mobility needs of people, freight and information in a manner that is the least damageable to the environment.
Sustainable development applied to transport systems requires the promotion of linkages between environmental protection, economic efficiency and social progress. Under the environmental dimension, the objective consists in understanding the reciprocal influences of the physical environment and the practices of the industry and that environmental issues are addressed by all aspects of the transport industry. Under the economic dimension, the objective consists of orienting progress in the sense of economic efficiency. Transport must be cost-effective and capable of adapting to changing demands. Under the social dimension, the objective consists in upgrading standards of living and quality of life.
Automobile dependence is a situation that is often related to an unsustainable urban environment. However, such an observation is at odd with the mobility choice and preferences of the global population where the automobile is rapidly adopted when income levels reach a certain threshold. Other transport alternatives commonly do not measure up to the convenience of the automobile. Automobile dependency is thus the outcome of market forces expressed as consumer preferences and national manufacturing policies. Private and flexible forms of transportation, such as the automobile, are thus fundamental to urban mobility and should not be discarded as options for the sake of sustainability.
Recent advances in car sharing technologies and the potential for self driving vehicles underline a much more sustainable usage of car assets that could remove up to 90% of the vehicles from the streets. This is in contradiction with the bias observed in the transport community towards an emphasis for public transit and non-motorized transportation as the dominant, if not sole, strategy towards sustainable transportation. Yet, almost all public transit systems are financially unsustainable, imposing burdens on the society. Freight transportation must also be considered in this process considering the substantial growth of raw materials and goods being traded in a global economy. In fact, freight transportation relies on much more environmentally sound modes such as rail and maritime transport.
Measures to promote transport sustainability have their limits. Indeed, the built environment, transport infrastructures and even modes cannot change quickly enough to solve the bulk of problems related to unsustainable transport. Most of the investment that is already in place will remain in place for 50 years or more and new investments (in additional or improved infrastructure) will not represent much more than a few percentage points change in terms of reducing traffic congestion and its negative externalities. While policies, rules and regulations expect compliance, users tend to instinctively react to price signals and discard modes that are becoming costly (unsustainable) and find loopholes.
Transportation and sustainability for both passengers and freight must also contend with mitigation versus adaptation issues:
  • Mitigation concerns the improvement of productivity and efficiency of existing modes, terminals and managerial approaches so that environmental externalities are reduced. They tend to be short to medium term strategies.
  • Adaptation is a change in the level of use and the market share of respective modes to better reflect a long term trend, such as higher energy prices and stricter environmental regulations.
There is a wide range of responses to environmental sustainability, with different local, national and international regulations. This involves a variety of costs in transport operations that must be built into the price of providing transport facilities and services. Environmental sustainability represents a growing area of responsibility for the providers of transport services, inciting them to acquire expertise in environmental management. The most important challenge is to implement environmentally sustainable transport within competitive market structures leaning on coping with changes in transport demand while improving transport supply.
3. Managing Transport Demand
In order to effectively mitigate the adverse impacts of current transportation systems, strategies can be devised to manage (reduce) transport demand for passengers and freight as wells as to redistribute this demand in space or in time when possible. Profitable, inexpensive and unsubsidized transportation is a good indicator of its sustainability. Increasing transport costs and the pressure to subsidize them can be interpreted as signals that they may be unsustainable. There are several interrelated ways in which transportation systems can adapt to cope with transport demand and reach a better level of sustainability:
  • Full-cost pricing. The full (or partial) recovery of costs related to public investments incurred in relation to constructing, repairing and operating transport networks. They remove artificial signals such as subsidies and let the users assume the real cost of transportation, which includes road pricing and pollution taxes and fees. Motorists are charged a floating fee (depending on the variability of demand in peak and off peak hours) for using targeted roads. This can be implemented through a variety of techniques such as tolls, or licensing fees. Tax and pollution fees would involve the implementation of increased taxes on vehicle and fuel purchasing as well as imposing fees on vehicle owners who operate at low levels of energy efficiency.
  • Parking controls. By raising parking prices or reducing the amount of parking space, such a strategy can be used to deter the use of privately owned vehicles in areas of highest demand by raising the price of commuting by car to high density areas. The expected result is to encourage (or force) commuters to seek other alternatives either in mass transit or carpooling. For freight distribution, they tend to be ineffective since delivery trucks will infringe regulations for short deliveries (e.g. double parking for a few minutes).
  • Trip avoidance. A more direct method of reducing traffic demand, but avoiding trips is a complex endeavor since it involves strategies where an activity still takes place while its related mobility is mitigated. This is mostly related to the use of information technologies. For instance, online shopping can reduce the number of trips to stores, but this involves a level of substitution to parcel deliveries. For freight transportation, trip avoidance is mostly the outcome of changes in sourcing strategies such as nearshoring where less ton-kms are generated.
  • Traffic bans. Through traffic bans the regional or municipal institutions would exert direct control over the allowable limit of vehicles in a given urban area depending on measures of transport supply-demand functions or arbitrary estimates of carrying capacity. 
The implementation of such strategies relies heavily on the existing spatial structure, people and material flows, and transport networks. An expectation is that the demand will shift towards modes that are more environmentally efficient and having a better energy performance. In situations where a fee structure is not effective (e.g. low income population), constraint based strategies can be more suitable than fee-based strategies. Such coercive strategies would thereby impose a limit on the number of vehicles in circulation and, correspondingly, reduce congestion and air pollution while promoting the use of alternative means of transport. Their fundamental shortfall is they assume that government entities actually know solutions to urban transport problems (such as the appropriate number of parking space), which is not necessarily the case.
4. Improving Transport Supply
While the implementation of demand oriented policies and mechanisms are an important component in promoting sustainable transport, it is pivotal that these measures be coupled with transport supply improvements. Transportation infrastructure should be expanded to accommodate rapidly growing transport demands. As long as the global urban population continues to grow, particularly in developing economies, there are pressures to expand urban transport infrastructures and well as infrastructure supporting global commercial interactions.
In urban areas the challenge is to expand and improve the transportation supply in such a way that the automobile and trucking can have alternatives. For passengers, this can be achieved by expanding public transit infrastructure, by improving existing public transit services, and by making cities friendly to pedestrians and non-motorized vehicles. However, it appears that vehicle automation could be an even more effective tool by allowing a better utilization of existing vehicle and road assets as well as reducing the number of vehicles in circulation. The realms of green logistics and city logistics have received renewed attention as tools to improve the sustainability of freight distribution since the material needs of economic activities, including end consumers, must be provided for as well.
The issue of sustainability is giving public transit a new impetus since the bulk of its prior rationale was to mitigate automobile dependency and provide equity in mobility. This is however an extremely difficult challenge considering the prominence that the automobile is achieving worldwide. It must be acknowledged that this prominence is the outcome of many positive factors favoring the automobile such as flexibility, convenience and relatively low costs. Thus, alternatives can be provided if they prove to be cost effective while fulfilling a niche demand. They may include:
  • Energy intensity of vehicles and carbon intensity of fuels. Vehicles are the first element of the transport supply where more sustainable improvements can be implemented. There are many strategies such as the usage of lighter materials (e.g. composites) for the manufacturing of vehicles or more efficient or new engine technologies. Fuels can also be improved upon through the use of alternatives such as natural gas, biofuels, electricity or hydrogen.
  • Densification and agglomeration. A higher level of concentration of activities usually lead to more efficient uses of transportation because of the lesser distances involved. Spatial structures such as logistics zones or transit oriented developments can thus result in reduced vehicle trips. They may also incite the use of modes more prone to economies of scale (more passengers or units of cargo per load or surface unit) as cost-effective alternatives. With market signals related to land cost, densification and agglomeration often dictate more efficient and higher density uses.
  • Context appropriate transport. Transportation modes and infrastructure must be developed and used in the context which they are the most appropriate. Both public and private forms of transportation have roles to fulfill since either a passenger or a unit of freight can go through a consolidation and deconsolidation process while in transit. The last decades have seen a substantial growth of individual transport in spite of all the efforts made to promote public transportation. In the North American context, promoting public transit has seen limited success. Therefore, public transportation, being less flexible, should assert a complementary role. The expansion and development of mass transit systems must make effective use of urban space by conforming to a number of factors including urban form, density, and modal preferences. In doing so, the fleets and networks must ensure a level of flexibility while ensuring low ridership costs. Comparatively, methods of improving and upgrading existing public transit services should include the improvement of service coverage and quality as well as increasing frequency where and when it is most needed (during peak hours). A similar observation applies to freight distribution as a range of modes are available to accommodate a variety of supply chains. There is not necessarily an ideal setting in which a mode should be used.
  • Non-motorized transport modes. The integration of individual modes of non-motorized transport such as walking and cycling can provide access to shopping, schools, and work for a growing proportion of the population. Also, for cities struggling with serious traffic congestion and air pollution, non-motorized transport should be considered as an alternative to private vehicles while serving as a crucial link in an integrated public transportation system. While cycling can be a challenging mode to promote and integrate in urban transportation (e.g. taxing weather conditions such as winter or excessive heat), there is a clear and unmet need to better integrate pedestrian movements into sound urban design and architecture.
Such alternatives are however in contrast with the modal choice reality of many economies towards the automobile and trucks, particularly those experiencing rapid growth. The issue of sustainable transport thus remains elusive since at start any economic activity, including transportation, has negative environmental impacts. The matter remains if these activities are taking place at a level exceeding the environmental and social carrying capacity.