Jean-Paul Rodrigue (2017), New York:
Routledge, 440 pages.
Author: Dr. Jean-Paul Rodrigue
1. Urban Mobility and its Evolution
Urban transportation is organized in three broad categories of
individual and freight transportation. While passenger movements
are the outcome of numerous individual decisions based on different
rationales, freight movements are decided in tandem between the
cargo owners (procurers and customers) and the transportation service
providers. In several instances, passengers and freight movements are
complementary to one another, but sometimes they may be competing for
passengers, the usage of available land and transport infrastructures:
Rapid urban development occurring across much of the globe implies
increased quantities of passengers and freight moving within urban
areas. Movements also tend to involve longer distances, but evidence
suggests that commuting times have remained relatively similar through
the last hundred years, approximately 1 to 1.2 hours per day. This means
that commuting has gradually shifted to faster transport modes and consequently
greater distances could be traveled using the same amount of time. Different
transport technologies and infrastructures have been implemented, resulting
in a wide variety of urban transport systems around the world. In developed
countries, there have been three general eras of urban development,
and each is associated with a different form of urban mobility:
- Collective Transportation (public transit). The purpose
of collective transportation is to provide publicly accessible mobility
over specific parts of a city. The systems are usually owned and
operated by an agency and access is open to all as long as a
fare is paid, therefore the reason why they are called public
transit. Its efficiency is based upon transporting
large numbers of people and achieving economies of scale. It includes
modes such as tramways, buses, trains, subways and ferryboats.
- Individual Transportation. Includes any mode where mobility
is the outcome of a personal choice and means such as the automobile,
walking, cycling and the motorcycle. The majority of people walk
to satisfy their basic mobility, but this number varies according
to the city considered. For instance, walking accounts for 88% of
all movements inside Tokyo while this figure is only 3% for Los
- Freight Transportation. As cities are dominant centers
of production and consumption, urban activities are accompanied
by large movements of freight. These movements are mostly characterized
by delivery trucks moving between industries, distribution centers,
warehouses and retail activities as well as from major terminals
such as ports, railyards, distribution centers and airports. The
mobility of freight within cities tends to be overlooked.
In many areas of the world where urbanization is more recent, the
above synthetic phases did not take place. In the majority of cases
fast urban growth led to a scramble to provide transport infrastructure
in an inadequate fashion. Each form of urban mobility, be it walking,
the automobile or urban transit has a
level of suitability
to fill mobility needs. Motorization and the diffusion of personal mobility
has been an ongoing trend linked with
substantial declines in the share of public transit in urban mobility.
2. A Taxonomy of Urban Mobilities
Movements are linked to specific urban activities and their land
use. Each type of land use involves the generation and attraction of
a particular array of movements.
This relationship is complex, but is linked to factors such as recurrence,
income, urban form, spatial
accumulation, level of development and technology. Urban movements are
either obligatory, when they are linked to scheduled activities
(such as home-to-work movements), or voluntary, when those generating
it are free to decide of their scheduling (such as leisure). The most
common types of urban movements are:
- The Walking-Horsecar Era (1800-1890). Even during the industrial revolution, the dominant mean of getting
around was on foot. Walking cities were typically less than 5 kilometers
in diameter, making it possible to walk from the downtown to the
city edge in about 30 minutes. Land use was mixed and density was
high (e.g. 100 to 200 people per hectare). The city was compact
and its shape was more-or-less circular. Still, the industrial
revolution brought additional populations through rural to urban
migrations, improved construction techniques allowing for higher
densities and new forms and locations of employment. The development of the
first public transit in the form of omnibus
service extended the diameter of the city but did not change
the overall urban structure. The railroad facilitated the first
real change in urban morphology. New developments, often referred
to as trackside suburbs, emerged as small
nodes that were physically separated from the city itself and from
one another. The nodes coincided with the location of rail stations
and stretched out a considerable distance from the city center,
usually up to a half hour train ride. Within the city proper, rail
lines were also laid down and horse-cars introduced mass transit.
- The Electric Streetcar or Transit Era (1890 - 1920s).
The invention of the electric traction motor created a revolution
in urban travel. The first electric trolley
line opened in 1888 in Richmond, Virginia. The operating speed of electric
trolley was three times faster than that of horse-drawn vehicles
and addition of not generating wastes.
The streetcar city was able to spread outward 20 to 30 kilometers along the streetcar
lines, creating an irregular, star-shaped
pattern. The urban fringes became areas of rapid residential
development. Trolley corridors became commercial strips that
would come to characterize the structure main commercial areas
of cities. The city
core was further entrenched as a mixed-use, high density zone. Land use patterns reflected social stratification where suburban
outer areas were typically middle class while the working class
continued to concentrate in the central city. As street congestion
increased in the first half of the 20th century due to the
diffusion of the automobile, the efficiency of streetcar systems
deteriorated as cars used their right of way. Further, many
cities had ordinances that prevented fare increases, implying
that many streetcar systems were unprofitable, leading to a lack
of maintenance and investment in additional services. These
factors contributed to the demise of many streetcar systems.
- The Automobile Era (1930s - 1950s). The automobile was
introduced in European and North American cities in the 1890's,
but only the wealthy could afford this innovation. From the 1920s,
ownership rates increased dramatically, with lower prices made possible
by Henry Ford's revolutionary assembly-line production techniques.
As automobiles became more common, land development patterns changed.
Developers were attracted to green-field areas located between the
suburban rail corridors, and the public was attracted to these single-use
zones, thus avoiding many inconveniences associated with city, mainly
pollution, crowding and lack of space. Still, this phase usually
represented the peak share of public transit in urban mobility
as suburban developments did not yet account for a large share
of the urban landscape and cities were still high density and
- The Freeway Era (1950s onward). After the
Second World War, the massive diffusion of the automobile as
well as the construction of highway networks had substantial
impacts on urban mobility. Highways were built to connect the
central business district to outlying areas and in many cases
complete or partial ring roads were built. The personal mobility
offered by the automobile represented a paradigm shift in terms
of lifestyle, consumption patterns as well as residential areas.
The automobile reduced the friction
of distance considerably, which led to urban sprawl. The
emergence of the suburb created a new landscape in which public
transit did not fit well. Transit ridership fell and transit companies ran into
financial difficulties and eventually transit services throughout
North America and Europe became subsidized, publicly-owned enterprises.
As time went on, commercial activities also began to suburbanize,
creating additional mobility systems of passengers and freight.
Within a short time, the automobile became the dominant mode of
travel in all cities of North America and from the 1970s in a
growing number of developed and developing economies. A similar
process took place in China at a massive scale in the 2000s.
The consideration of urban movements, both for passengers and
freight, involves their generation, the
modes and routes used and their destination:
- Pendulum movements. These are obligatory movements involving
commuting between locations of residence and work. They are highly
cyclical since they are predictable and recurring on a regular basis,
most of the time a daily occurrence, thus the term pendulum.
- Professional movements. These are movements linked to
professional, work-based, activities such as meetings and customer
services, dominantly taking place during work hours.
- Personal movements. These are voluntary movements linked
to the location of commercial activities, which includes shopping
- Touristic movements. Important for cities having historical
and recreational features they involve interactions between landmarks
and amenities such as hotels and restaurants. They tend to be seasonal
in nature or occurring at specific moments. Major sport events such
as the World Cup or the Olympics are important generators of urban
movements during their occurrence.
- Distribution movements. These are concerned with the
distribution of freight to satisfy consumption and manufacturing
requirements. They are mostly linked to transport terminals, distribution centers and retail
outlets. However, the growth of online transactions involves
more freight movements being carried to residential areas.
Mobility is also a social equity issue. The share of the automobile in urban trips varies in relation to
location, social status, income, quality of public transit and parking
availability. Mass transit is often affordable, but several social groups,
such as students, the elderly and the poor are a captive market.
There are important variations in mobility according to age, income,
gender and disability. The gender
gap in mobility is the outcome of socio-economic differences as
access to individual transportation is dominantly a matter of income.
Within households, differences in role and income are related to the
respective activity range and mobility of its members.
Consequently, in some instances modal choice is more a modal constraint
linked to economic opportunities.
Central locations are generally having the most urban mobility
options because private and public transport facilities are present.
However, this does not mean that mobility is easier since central
areas are congested. In locations outside the central core, a share of the population
not having access to the automobile is facing a level of isolation, or
at least a more limited access to amenities and employment opportunities. Limited public transit and high automobile
ownership costs have created a class of
spatially constrained (mobility deprived) people.
Transit is almost exclusively an urban transportation mode, particularly
in large urban agglomerations. The urban environment is particularly
suitable for transit because it provides conditions fundamental to its
efficiency, namely high density and significant short distance
mobility demands. Since transit is a shared service,
it potentially benefits from economies of agglomeration related to high
densities and from economies of scale related to high mobility demands.
One key advantage of public transit is the higher the demand,
the more effectively public transit services can be offered. Lower
densities are linked with lower
demand and a greater likelihood of public transit systems operating at a loss
and requiring subsidies.
In fact, most public transit systems are not financially
sound and have to be subsidized. Transit
systems are made up of many types of services, each suitable to
a specific set of market and spatial context. Different modes are used
to provide complementarity services within the transit system and in
some cases between the transit system and other transport systems.
- Trip generation. On average, an urban resident undertakes
between 3 and 4 trips per day. Moving in an urban area is usually
done to satisfy a purpose such as
employment, leisure or access to goods and services. Each time a
purpose is satisfied, a trip is generated.
Important temporal variations in the
number of trips by purpose are observed with the most prevalent
pattern being commuting. Similar temporal variations are
observed for freight movements with the majority of movements
taking place in the morning when goods are delivered to retail
outlets. This often leads to
conflicts with passengers transport since vehicles are
sharing the same road infrastructure which in urban areas is the
object of capacity constraints.
- Modal split. Implies the use of a
series of transportation mode for urban trips, which is the outcome
of a modal choice. This choice depends on a number of factors
such as cost, technology, availability, preference, travel time
(distance) and income. Therefore, walking, cycling, public
transit, the automobile or even telecommuting, are going to be
used either as a choice or as a constraint (lack of choice). For instance,
locations within five
minutes of walking are considered to be readily accessible to
pedestrians. Urban freight distribution can also use a variety
of modes, but the van and the truck tend to dominate.
- Trip assignment (routing). Involves which routes will be used for
journeys within the city. Passenger trips usually have a stable
routing. For instance, a commuter driving a car
has most of the time a fixed route between his residence and
place of work. This route may be modified if
there is congestion or if another activity (such as shopping) is
linked with that trip; a practice often known as trip chaining.
The routing of freight distribution is dependent on the types of
deliveries involved. For large retail outlets direct deliveries
are the norm while for smaller stores and parcel deliveries,
vehicles will accommodate flexible routing. Several
factors influence trip assignment, the two most important being
transport costs, time and
- Trip destination. Changes in the spatial distribution
of economic activities in urban areas have caused
important modifications to the destination
of movements, notably those related to work. Activity-based
considerations are important since each economic activity tends
to be associated with a level of trip attraction. Retail, public
administration, entertainment and restoration are the
activities that attract the most movements per person employed.
For freight movements, manufacturing, transport terminals and
retail are the activities attracting the most movements. The central
city used to be a major destination for movements,
particularly passengers, but its share
has substantially declined in most areas and suburbs now
account for the bulk of urban movements.
Contemporary transit systems tend to be publicly owned, implying
that many decisions related to their development and operation are politically
motivated. This is a sharp contrast of what took place in the past as most transit systems
were private and profit driven initiatives. With the fast diffusion
of the automobile in the 1950s, many transit companies faced financial
difficulties, and the quality of their service declined; in a declining
market there were limited incentives to invest. Gradually, they were
purchased by public interests and incorporated into large agencies,
mainly to continue providing mobility. As such, public transit often
serves more a social function of public service and a tool of social
equity than having an economic role. Transit has become dependent
on government subsidies, with little if any competition permitted as
wages and fares are regulated. As a result, they tend to be disconnected
from market forces and subsidies are constantly required to keep a level
of service. With suburbanization transit systems tend to have even less
relationships with economic activities.
Government owned public transit systems are facing financial
difficulties for three main reasons. The first is that they are
often designed to service taxpayers, not necessarily potential
customers. Because of the funding base, transit systems may be
spread into neighborhoods that do not provide a significant customer
base. The second is that transit unions were able to extract
significant advantages in terms of wages and social benefits,
increasing labor costs. The third concerns a technology fixation
which incites to invest in high cost transit (e.g.
light rail transit) while
low cost solutions (buses) would have been sufficient to many
transit systems, particularly in lower density areas.
Reliance on urban transit as a mode
of urban transportation tends to be high in Asia, intermediate in Europe
and low in North America. Since their inception in the early 19th century,
comprehensive urban transit systems had significant impacts on the urban
form and spatial structure, but this influence is receding.
Three major classes of cities
can be found in terms of the relationships they have with their
One of the most common form of urban transit that include
vehicles of various sizes (from small vans to articulated
buses) offering seating and standing capacity along
scheduled routes and services. They usually share roadways
with other modes and are therefore susceptible to
congestion. Bus rapid transit systems offer permanent or
temporary right of ways and have the advantage of
Rail transit. Vehicles of fixed guideways
that usually have their own right of way.
Light rail systems are composed
of streetcars that can share right of ways, particularly in
central areas. Heavy rail systems are commonly called
subways or metro since many operate underground. Another
type of rail transit concerns commuter rail systems that are
usually servicing central business districts and peripheral
areas along specific corridors.
Taxi systems. Usually private for hire
vehicles such as automobiles, jitneys or rickshaws to offer
point to point services. Recent technological developments
have enabled car sharing services and expanded the
availability of on demand transit.
Alternative transit. Refer to transit
systems that were developed to cope with specific conditions
(or niche markets)
using alternative modes. Ferries are the most common form of
alternative transit as they are servicing cities having
waterways separating different urban districts. Funiculars
are also prevalent in locations have a steep incline and
enough traffic to justify their construction. Aerial lifts
are also used in some settings to connect locations
difficult of access.
Contemporary land development tends to precede the introduction
of urban transit services, as opposed to concomitant developments
in earlier phases of urban growth. Thus, new services are established
once a demand is deemed to be sufficient, often after being the subject of public
pressures. Transit authorities operate under a service warrant and are
often running a recurring deficit as services are becoming more expensive
to provide. This has led to a set of considerations aimed at a higher
integration of transit in the urban planning process, especially in
North America, where such a tradition is not well established. Still,
in spite of decades of investment, North American public transit ridership
has roughly remained the same throughout the 1980s and 1990s, but
has increased since then, leading to expectations that they may become
From a transportation perspective, the potential benefits of a better
integration between transit and local land uses are reduced trip frequency
and increased use of alternative modes of travel (i.e. walking, biking
and transit). Evidence is often lacking to support such expectations
since the relative share of public transit ridership is declining across
the board. There is often a reciprocal relationship between
automobile ownership and the use of public transit. Good accessibility
to public transit is often associated with lower automobile use while
areas of high automobile use may impair the development of public
transit systems since the automobile is already dominant.
Community and land use design can consequently have a significant influence
on travel patterns. Local land use impacts can be categorized in
three dimensions of relationships
and are influenced by levels of use. Land use initiatives should be
coordinated with other planning and policy initiatives to cope with
automobile dependence. However, there is a strong bias against transit
in the general population because of negative perceptions, especially
in North America, but increasingly globally. As personal mobility is
a symbol of status and economic success, the users of public transit
are perceived as the least successful segment of the population. This
bias may undermine the image of transit use within the general population,
but can be subject to change with the evolution of social norms and
- Adaptive cities. Represent true transit-oriented cities
where urban form and urban land use developments are coordinated
with transit developments. While central areas are adequately serviced
by a metro system and are pedestrian friendly, peripheral areas
are oriented along transit rail lines.
- Adaptive transit. Represent cities where transit plays
a marginal and residual role and where the automobile accounts for
the dominant share of movements. The urban form is decentralized
and of low density.
- Hybrids. Represent cities that have sought a balance
between transit development and automobile dependency. While central
areas have an adequate level of service, peripheral areas are automobile-oriented.