Jean-Paul Rodrigue (2017), New York:
Routledge, 440 pages.
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
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
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
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
Societies do not contribute to environmental problems at the same
level. Sustainability can be thus expressed at two spatial levels:
- 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
- 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.
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
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.
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.
advances in car sharing technologies and the potential for
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
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:
- 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.
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:
- 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
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
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
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:
- 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.
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.
- 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
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
- 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
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