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THE GEOGRAPHY OF TRANSPORT SYSTEMS

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o Table of Contents o Chapter 1 - Transportation and Geography o Chapter 2 - Transportation and the Spatial Structure o Chapter 3 - Transportation Modes o Chapter 4 - Transport Terminals o Chapter 5 - International Trade and Freight Distribution o Chapter 6 - Urban Transportation o Chapter 7 - Transportation and the Economy o Chapter 8 - Transport, Energy and Environment o Chapter 9 - Transport Planning and Policy o Appendix - Methods in Transport Geography

media Glossary links About

SECOND EDITIONJean-Paul Rodrigue, Claude Comtois and Brian Slack (2009), New York: Routledge, 352 pages.

ISBN 978-0-415-48324-7 Home > Contents > Chapter 6 > Concept 4Urban Transport Problems Author: Dr. Jean-Paul Rodrigue 1. Challenges Facing Urban Transportation Cities are locations having a high level of accumulation and concentration of economic activities and are complex spatial structures that are supported by transport systems. The larger the city, the greater its complexity and the potential for disruptions if this complexity is not effectively managed. The most important transport problems are often related to urban

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areas and take place when transport systems, for a variety of reasons, cannot satisfy the numerous requirements of urban mobility. Urban productivity is highly dependent on the efficiency of its transport system to move labor, consumers and freight between multiple origins and destinations. Additionally, important transport terminals such as ports, airports, and railyards are located within urban areas, contributing to a specific array of problems. Some problems are ancient, like congestion (which plagued cities such as Rome), while others are new like urban freight distribution or environmental impacts. Among the most notable urban transport problems are:

Traffic congestion and parking difficulties. Congestion is one of the most prevalent transport problems in large urban agglomerations, usually above a threshold of about 1 million inhabitants. It is particularly linked with motorization and the diffusion of the automobile, which has increased the demand for transport infrastructures. However, the supply of infrastructures has often not been able to keep up with the growth of mobility. Since vehicles spend the majority of the time parked, motorization has expanded the demand for parking space, which has created space consumption problems particularly in central areas; the spatial imprint of parked vehicles is significant. Congestion and parking are also interrelated since looking for a parking space (called "cruising") creates additional delays and impairs local circulation. In central areas of large cities cruising may acount for more than 10% of the local circulation as drivers can spend 20 minutes looking for a parking spot. This practice is often judged more economically effective than using a paying off-street parking facility as the time spent looking for a parking space as compensated by the monetary savings. Also, many delivery vehicles will simply double-park at the closest possible spot to unload their cargo.

Longer commuting. On par with congestion people are spending an increasing amount of time commuting between their residence and workplace. An important factor behind this trend is related to residential affordability as housing located further away from central areas (where most of the employment remains) is more affordable. Therefore, commuters are trading time for housing affordability. However, long commuting is linked with several social problems, such as isolation, as well as poorer health (obesity).

Public transport inadequacy. Many public transit systems, or parts of them, are either over or under used. During peak hours, crowdedness creates discomfort for users as the system copes with a temporary surge in demand. Low ridership makes many services financially unsustainable, particularly in suburban areas. In spite of significant subsidies and cross-financing (e.g. tolls) almost every public transit systems cannot generate sufficient income to cover its operating and capital costs. While in the past deficits were deemed acceptable because of the essential service public transit was providing for urban mobility, its financial burden is increasingly controversial.

Difficulties for non-motorized transport. These difficulties are either the outcome of intense traffic, where the mobility of pedestrians, bicycles and vehicles is impaired, but also because of a blatant lack of consideration for pedestrians and bicycles in the physical design of infrastructures and facilities.

Loss of public space. The majority of roads are publicly owned and free of access. Increased traffic has adverse impacts on public activities which once crowded the streets such as markets, agoras, parades and processions, games, and community interactions. These have gradually disappeared to be replaced by automobiles. In many cases, these

activities have shifted to shopping malls while in other cases, they have been abandoned altogether. Traffic flows influence the life and interactions of residents and their usage of street space. More traffic impedes social interactions and street activities. People tend to walk and cycle less when traffic is high.

Environmental impacts and energy consumption. Pollution, including noise, generated by circulation has become a serious impediment to the quality of life and even the health of urban populations. Further, energy consumption by urban transportation has dramatically increased and so the dependency on petroleum. Yet, peak oil considerations are increasingly linked with peak mobility expectations where high energy prices incite a shift towards more efficient and sustainable forms of urban transportation, namely public transit.

Accidents and safety. Growing traffic in urban areas is linked with a growing number of accidents and fatalities, especially in developing countries. Accidents account for a significant share of recurring delays. As traffic increases, people feel less safe to use the streets.

Land consumption. The territorial imprint of transportation is significant, particularly for the automobile. Between 30 and 60% of a metropolitan area may be devoted to transportation, an outcome of the over-reliance on some forms of urban transportation. Yet, this land consumption also underlines the strategic importance of transportation in the economic and social welfare of cities.

Freight distribution. Globalization and the materialization of the economy have resulted in growing quantities of freight moving within cities. As freight traffic commonly shares infrastructures with the circulation of passengers, the mobility of freight in urban areas has become increasingly problematic. City logistics strategies can be established to mitigate the variety of challenges faced by urban freight distribution.

Many dimensions to the urban transport problem are linked with the dominance of the automobile. 2. Automobile Dependency Automobile use is obviously related to a variety of advantages such as on demand mobility, comfort, status, speed, and convenience. These advantages jointly illustrate why automobile ownership continues to grow worldwide, especially in urban areas. When given the choice and the opportunity, most individuals will prefer using an automobile. Several factors influence the growth of the total vehicle fleet, such as sustained economic growth (increase in income and quality of life), complex individual urban movement patterns (many households have more than one automobile), more leisure time and suburbanization. Therefore, rising automobile mobility can be perceived as a positive consequence of economic development. The acute growth in the total number of vehicles also gives rise to congestion at peak traffic hours on major thoroughfares, in business districts and often throughout the metropolitan area. Cities are important generators and attractors of movements, which have created a set of geographical paradoxes that are self-reinforcing. For instance, specialization leads to additional transport demands while agglomeration leads to congestion. Over time, a state of automobile dependency has emerged which results in a diminution in the role of other modes, thereby limiting still further alternatives to urban mobility. In addition to the factors contributing to the growth of driving, two major factors contributing to automobile dependency are:

Underpricing and consumer choices. Most road infrastructures are subsidized as they are considered a public service. Consequently, drivers do not bear the full cost of automobile use. Like the "Tragedy of the Commons", when a resource is free of access (road), it tends to be overused and abused (congestion). This is also reflected in consumer choice, where automobile ownership is a symbol of status, freedom and prestige, especially in developing countries. Single home ownership also reinforces automobile dependency.

Planning and investment practices. Planning and the ensuing allocation of public funds aim towards improving road and parking facilities in an ongoing attempt to avoid congestion. Other transportation alternatives tend to be disregarded. In many cases, zoning regulations impose minimum standards of road and parking services and de facto impose a regulated automobile dependency.

There are several levels of automobile dependency, ranging from low to acute, with their corresponding land use patterns and alternatives to mobility. Among the most relevant indicators of automobile dependency are the level of vehicle ownership, per capita motor vehicle mileage and the proportion of total commuting trips made using an automobile. A situation of high automobile dependency is reached when more than three quarters of commuting trips are done using the automobile. For the United States, this proportion has remained around 88% over the recent decades. Automobile dependency is also served by a cultural and commercial system promoting the automobile as a symbol of status and personal freedom, namely through intense advertising and enticements to purchase new automobiles. Not surprisingly, many developing countries perceive motorization as a condition for development. Even if the term automobile dependency is often negatively perceived and favored by market distortions such as the provision of roads, its outcome reflects the choice of individuals who see the automobile more as an advantage then an inconvenience. The second half of the 20th century saw the adaptation of many cities in North America and Europe to automobile circulation. Motorized transportation was seen as a powerful symbol of modernity and development. Highways were constructed, streets were enlarged, and parking lots were set often disrupting the existing urban fabric with the creation of motorized cities. However, from the 1980s, motorization started to be seen more negatively and several cities implemented policies to limit automobile circulation, at least in specific areas, by a set of strategies including:

Dissuasion. Although automobile circulation is permitted, it is impeded by regulations and physical planning. For instance, parking space can be severely limited and speed bumps placed to force speed reduction.

Prohibition of downtown circulation. During most of the day the downtown area is closed to automobile circulation but deliveries are permitted during the night. Such strategies are often undertaken to protect the character and the physical infrastructures of an historical city. They do however, like most policies, have unintended consequences. If mobility is restrained in certain locations or during certain time periods, people will simply go elsewhere (longer movements) or defer their mobility for another time (more movements).

Tolls. Imposing tolls for parking and entry (congestion pricing) to some parts of the city has been a strategy being considered seriously in many area as it confers the potential advantage of congestion mitigation and revenue generation. Most evidence underlines

however that drivers are willing to bear additional toll costs, especially for commuting since it is linked with their main income.

Tentative solutions have been put forth such as transport planning measures (synchronized traffic lights, regulated parking), limited vehicle traffic in selected areas, the promotion of bicycle paths and public transit. In Mexico City, vehicle use is prohibited according to license plate numbers and the date (even-uneven). Affluent families have solved this issue by purchasing a second vehicle, thus worsening the existing situation. Singapore is the only country in the world which has successfully controlled the amount and growth rate of its vehicle fleet by imposing a heavy tax burden and purchasing permits on automobile owners. Such a command-based approach is unlikely to be possible on other contexts. There is a growing body of evidence underlining that a peak level of car mobility is unfolding, at least in developed countries. Higher energy prices, congestion and the general aging of the population are all countervailing forces to car dependency. For instance, since 2006 the amount of vehicle-miles traveled in the United States has peaked, a process associated with higher energy prices and a strong recession. There are many alternatives to automobile dependency such as intermodality (combining the advantages of individual and collective transport), carpooling (strengthened by policy and regulation by the US government) or non-motorized transportation (walking and cycling). These alternatives can only be partially implemented as the automobile remains on the short and medium terms the prime choice for providing urban mobility. 3. Congestion Congestion occurs when transport demand exceeds transport supply at a specific point in time and in a specific section of the transport system. Under such circumstances, each vehicle impairs the mobility of others.Congestion can be perceived as an unavoidable consequence of the usage of scarce transport resources, particularly if they are not priced. The last decades have seen the extension of roads in rural but particularly in urban areas, most of them free of access. Those infrastructures were designed for speed and high capacity, but the growth of urban circulation occurred at a rate higher than often expected. Investments came from diverse levels of government with a view to provide accessibility to cities and regions. There were strong incentives for the expansion of road transportation by providing high levels of transport supply. This has created a vicious circle of congestion which supports the construction of additional road capacity and automobile dependency. Urban congestion mainly concerns two domains of circulation, often sharing the same infrastructures:

Passengers. In many regions of the world incomes have significantly increased to the point that one automobile per household or more is common. Access to an automobile conveys flexibility in terms of the choice of origin, destination and travel time. The automobile is favored at the expense of other modes for most trips, including commuting. For instance, automobiles account for the bulk of commuting trips in the United States.

Freight. Several industries have shifted their transport needs to trucking, thereby increasing the usage of road infrastructure. Since cities are the main destinations for freight flows (either for consumption or for transfer to other locations) trucking adds to further congestion in urban areas. The "last mile" problem remains particularly prevalent for freight distribution in urban areas. Congestion is commonly linked with a drop in the frequency of deliveries tying additional capacity to insure a similar level of service.

It is important to underline that congestion in urban areas is dominantly caused by commuting patterns and little by truck movements. On average, infrastructure provision was not able to keep up with the growth in the number of vehicles, even more with the total number of vehicles-km. During infrastructure improvement and construction, capacity impairment (fewer available lanes, closed sections, etc.) favors congestion. Important travel delays occur when the capacity limit is reached or exceeded, which is the case of almost all metropolitan areas. In the largest cities such as London, road traffic is actually slower than it was 100 years ago. Marginal delays are thus increasing and driving speed becomes problematic as the level of population density increases. Once a population threshold of about 1 million is reached, cities start to experience recurring congestion problems. This observation must be nuanced by numerous factors related to the urban setting, modal preferences and the quality of existing urban transport infrastructures. Still, large cities have become congested most of the day, and congestion is getting more acute. Another important consideration concerns parking, which consumes large amounts of space and provides limited economic benefit. In automobile dependent cities, this can be very constraining as each economic activity has to provide an amount of parking space proportional to their level of activity. Parking has become a land use that greatly inflates the demand for urban land. Urban mobility also reveals congestion patterns. Daily trips can be either “mandatory” (workplace-home) or “voluntary” (shopping, leisure, visits). The former is often performed within fixed schedules while the latter complies with variable and discretionary schedules. Correspondingly, congestion comes in two major forms:

Recurrent congestion. The consequence of factors that cause regular demand surges on the transportation system, such as commuting, shopping or weekend trips. However, even recurrent congestion can have unforeseen impacts in terms of its duration and severity. Mandatory trips are mainly responsible for the peaks in circulation flows, implying that about half the congestion in urban areas is recurring at specific times of the day and on specific segments of the transport system.

Non-recurrent congestion. The other half of congestion is caused by random events such as accidents and unusual weather conditions (rain, snowstorms, etc.), which are unexpected and unplanned. Non-recurrent congestion is linked to the presence and effectiveness of incident response strategies. As far as accidents are concerned, their randomness is influenced by the level of traffic as the higher the traffic on specific road segments the higher the probability of accidents.

Behavioral and response time effects are also important as in a system running close to capacity, simply breaking suddenly may trigger what can be known as a backward traveling wave. It implies that as vehicles are forced to stop, the bottleneck moves up the location it initially took place at, often leaving drivers puzzled about its cause. The spatial convergence of traffic causes a surcharge on transport infrastructures up to the point where congestion can lead to the total immobilization of traffic. Not only does the massive use of the automobile have an impact on traffic circulation and congestion, but it also leads to the decline in public transit efficiency when both are sharing the same roads. 4. Mitigating Congestion In some areas, the automobile is the only mode for which infrastructures are provided. This implies less capacity for using alternative modes such transit, walking and cycling. At some levels of density, no public infrastructure investment can be justified in terms of economic returns. Longer commuting trips in terms of average travel time, the result of fragmented land uses and congestion levels are a

significant trend. Convergence of traffic at major highways that serve vast low density areas with high levels of automobile ownership and low levels of automobile occupancy. The result is energy (fuel) wasted during congestion (additional time) and supplementary commuting distances. In automobile dependent cities, a few measures can help alleviate congestion to some extent:

Ramp metering. Controlling the access to a congested highway by letting automobiles in one at a time instead of in groups. The outcome is a lower disruption on highway traffic flows.

Traffic signal synchronization. Tuning the traffic signals to the time and direction of traffic flows. This is particularly effective if the signals can be adjusted on an hourly basis to reflect changes in commuting patterns.

Incident management. Making sure that vehicles involved in accidents or mechanical failures are removed as quickly as possible from the road. Since accident on average account between 20 and 30% of all the causes of congestion, this strategy is particularly important.

Carpooling. Concerns two issues. The first and most common is an individual providing ridership to people (often co-workers) having a similar origin, destination and commuting time. Two or more vehicle trips can thus be combined into one. The second involves a pool of vehicles (mostly cars, but also bicycles) that can be leased for short durations when mobility is required. Adequate measures must be taken so that supply and demand are effectively matched.

HOV lanes. High Occupancy Vehicle (HOV) lanes insure that vehicles with 2 or more passengers (buses, vans, carpool, etc.) have exclusive access to a less congested lane, particularly during peak hours.

Congestion pricing. A variety of measures aimed at imposing charges on specific segments or regions of the transport system, mainly as a toll. The charges can also change during the day to reflect congestion levels so that drivers are incited to consider other time periods or other modes.

Parking management. Removing parking or free parking spaces can be an effective dissuasion tool since it reduces cruising and enables those willing to pay to access an area (e.g. for a short shopping stop).

Public transit. Offering alternatives to driving that can significantly improve efficiency, notably if it circulates on its own infrastructure (subway, light rail, buses on reserved lanes, etc.) and is well integrated within a city's development plans. However, public transit has its own set of issues (see next section).

Non-motorized transportation. Since the great majority of urban trips are over short distances, non-motorized modes, particularly walking and cycling, have an important roll to play in supporting urban mobility. The provision of adequate infrastructure, such as sidewalks, is often a low priority as non-motorized transportation is often perceived as not modern in spite of the important role it needs to assume in urban areas.

All these measures only partially address the issue of congestion, as they alleviate, but do not solve the problem. Fundamentally, congestion remains a failure at reconciling mobility demands and acute supply constraints. 5. The Urban Transit Challenge As cities continue to become more dispersed, the cost of building and operating public transportation systems increases. For

instance, only about 80 large urban agglomerations have a subway system, the great majority of them being in developed countries. Furthermore, dispersed residential patterns characteristic of automobile dependent cities makes public transportation systems less convenient to support urban mobility. In many cities additional investments in public transit did not result in significant additional ridership. Unplanned and uncoordinated land development has led to rapid expansion of the urban periphery. Residents, by selecting housing in outlying areas, restrict their potential access to public transportation. Over-investment (when investments do not appear to imply significant benefits) and under-investment (when there is a substantial unmet demand) in public transit are both complex challenges. Urban transit is often perceived as the most efficient transportation mode for urban areas, notably large cities. However, surveys reveal a stagnation or a decline of public transit systems, especially in North America. The economic relevance of public transit is being questioned. Most urban transit developments had little, if any impacts to alleviate congestion in spite of mounting costs and heavy subsidies. This paradox is partially explained by the spatial structure of contemporary cities which are oriented along servicing the needs of the individual, not necessarily the needs of the collectivity. Thus, the automobile remains the preferred mode of urban transportation. In addition, public transit is publicly owned, implying that it is a politically motivated service that provides limited economic returns. Even in transit-oriented cities such as in Europe, transit systems depend massively on government subsidies. Little or no competition is permitted as wages and fares are regulated, undermining any price adjustments to changes in ridership. Thus, public transit often serves the purpose of a social function (“public service”) as it provides accessibility and social equity, but with limited relationships with economic activities. Among the most difficult challenges facing urban transit are:

Decentralization. Public transit systems are not designed to service low density and scattered urban areas that are increasingly dominating the landscape. The greater the decentralization of urban activities, the more difficult and expensive it becomes to serve urban areas with public transit. Additionally, decentralization promotes long distance trips on transit systems causing higher operating costs and revenue issues for flat fare transit systems.

Fixity. The infrastructures of several public transit systems, notably rail and subway systems are fixed, while cities are dynamical entities, even if the pace of change can take decades. This implies that travel patterns tend to change and that a transit system built for servicing a specific pattern may eventually face "spatial obsolescence".

Connectivity. Public transit systems are often independent from other modes and terminals. It is consequently difficult to transfer passengers from one system to the other. This lead to a paradox between the preference of riders to have direct connections and the need to provide a cost efficient service network that involves transfers.

Competition. In view of cheap and ubiquitous road transport systems, public transit faced strong competition and loss ridership in relative terms and in some cases in absolute terms. The higher the level of automobile dependency, the more inappropriate the public transit level of service. The public service being offered is simply outpaced by the convenience of the automobile. However, changes in energy prices are likely to impose a new equilibrium in this relationship.

Financing and fare structures. Most public transit systems have abandoned a distance-based fare structure to a simpler flat fare system. This had the unintended consequence of

discouraging short trips for which most transit systems are well suited for, and encouraging longer trips that tend to be more costly per user than the fares they generate. Information systems offer the possibility for transit systems to move back to a more equitable distance based fare structure.

Legacy costs. Most public transit systems employ unionized labor that have consistently used strikes (or the threat of a strike) and the acute disruptions they create as leverage to negotiate favorable contracts, including health and retirement benefits. Since public transit is subsidized these costs were not well reflected in the fare systems. In many transit systems, additional subsidies went into compensation or to cover past debt, and not necessarily into performance improvements or additional infrastructure. As most governments are facing stringent budgetary constraints because of unsustainable social welfare commitments, public transit agencies are being forced to reassess their budgets through an unpopular mix of higher fares, deferred maintenance and the breaking of labor contracts. The era of public transit as a welfare agency providing compensation and benefits well above the qualifications and the productivity of its labor may be drawing to an end.

There are indications that public transit is reassessing its role in societies with high levels of automobile dependency. The rise in petroleum prices since 2006 is increased the cost of vehicle ownership and operation. A younger generation is perceiving the automobile as a less attractive proposition than the prior generation and is more willing to use public transit and live in higher density areas. Electronic fare systems are also making the utilization of public transit more convenient. A recent trend concerns the usage of incentives, such as point systems (e.g. air miles with purchase of a monthly pass) to further promote the use of public transit and to influence consumer behavior. Related Topics Transportation and the Urban Form Urban Land Use and Transportation Urban Mobility City Logistics Transportation and Sustainability

Media Central Business District Monthly Parking Rate Parking in a

Public Park, Brussels 2003 Land Area Consumed by the Car in Selected Countries,

1999 Percentage of Households by Number of Vehicles, 1977-2005

Geographical Paradoxes behind Urban Transport Problems City Logistics and Land

Use Factors Contributing to the Growth of Driving Levels of

Automobile Dependency Space / Time Relationships and Modal Choice

Indicators of Automobile Dependency Home-to-Work Trips Modes,

United States, 1985-2004 Annual Vehicle-Miles Traveled in the United States and

Year-over-Year Changes Vicious Circle of Congestion Backward

Propagation of a Traffic Jam 100 Most Congested Highway Intersections in the

United States, 2006 Average Number of Hours of Delay per Peak Commuter per

Year, Selected American Cities, 1982-2003 Average Daily Commuting Time,

European Countries, 2002 Urban Density and Driving Speed, Selected Global Cities

City Size and Roadway Congestion Index, United States, 1982-2009

Traffic Conditions in Major American Cities, 1982-2003 Parking Accumulation by

Land Use by Time of the Day Major Sources of Recurring and Non-Recurring

Congestion Recurring Congestion Average Hourly Traffic on George

Washington Bridge, 2002 Home-to-Work Commute Profile, United States, 1983-

2003 Bicycle Pool, Paris, France Transit Use and Car Ownership in

Selected Cities, 1993 Largest Subway Systems in the World by Annual Ridership

and Metropolitan Population, 2000 Estimated Ridership of the World’s Largest

Public Transit Systems, 1998 Trips by Public Transport in the United States, 1970-

2005 Source of Revenue for Bus Operations, Europe, 2002 Fare

Recovery Ratio of Selected Public Transit Systems, United States Challenges of Urban Transit Home | Contents | Media | Glossary | Links | About | Contact | Purchase Copyright © 1998-2012, Dr. Jean-Paul Rodrigue, Dept. of Global Studies & Geography , Hofstra University, New York, USA.This material (including graphics) cannot be copied or redistributed, in whole or in part, in ANY FORM (printed or electronic) and on ANY MEDIA. For specific uses permission MUST be requested and the material must be cited.

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THE GEOGRAPHY OF TRANSPORT SYSTEMS

Home Contents

o Table of Contents o Chapter 1 - Transportation and Geography o Chapter 2 - Transportation and the Spatial Structure o Chapter 3 - Transportation Modes o Chapter 4 - Transport Terminals o Chapter 5 - International Trade and Freight Distribution o Chapter 6 - Urban Transportation o Chapter 7 - Transportation and the Economy o Chapter 8 - Transport, Energy and Environment o Chapter 9 - Transport Planning and Policy o Appendix - Methods in Transport Geography

media Glossary links About

SECOND EDITIONJean-Paul Rodrigue, Claude Comtois and Brian Slack (2009), New York: Routledge, 352 pages.

ISBN 978-0-415-48324-7 Home > Contents > Chapter 6 > Concept 3Urban Mobility Author: Dr. Jean-Paul Rodrigue 1. Urban Mobility and its Evolution Urban transportation is organized in three broad categories of collective, individual and freight transportation. While passengers movements are the outcome of numerous individual decisions based on different rationales, freight movements are decided in tendem between the cargo owners (procurer and customer) 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:

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Collective Transportation (public transit). The purpose of collective transportation is to provide publicly accessible mobility over specific parts of a city. 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 account for 88% of all movements inside Tokyo while this figure is only 3% for Los Angeles.

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.

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:

The Walking-Horsecar Era (1800-1890). Even during the onslaught of the industrial revolution, the dominant mean of getting around was on foot. 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. 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. These 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. The operating speed of electric trolley was three times faster than that of horse-drawn vehicles. The city 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. The city core was further entrenched as a mixed-use, high density zone. Overall densities were reduced to

between 50 and 100 people per hectare. 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, the efficiency of streetcar systems deteriorated and fell of favor; many were abandoned.

The Automobile Era (1930 onward). 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 axes, and the public was attracted to these single-use zones, thus avoiding many inconveniences associated with city, mainly pollution, crowding and lack of space. 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. Within a short time, the automobile was the dominant mode of travel in all cities of North America. The automobile has reduced the friction of distance considerably which has lead to urban sprawl.

In many areas of the world where urbanization is more recent, the above synthetic phases did not took 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 private car 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:

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 and recreation.

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.

The consideration of urban movements involves their generation, the modes and routes used and their destination:

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 of the number of trips by purpose are observed with the most prevalent pattern being pendulum movements.

Modal split. Implies which transportation mode is used for urban trips and is the outcome of a modal choice. Modal choice depends on a number of factors such as technology, availability, preference, travel time (distance) and income. For instance, everything within five minutes of walking is considered to be readily accessible to pedestrians.

Trip assignment (routing). Involves which routes will be used for journeys within the city. For instance, a commuter driving a car has most of the time a fixed route. 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. Several factors influence trip assignment, the two most important being transport costs and availability.

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 restauration are the activities that attract the most movements per person employed. The central city used to be a major destination for movements, but its share has substantially declined in most areas and suburbs now account for the bulk of urban movements.

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 so called gender gap in mobility is the outcome of socio-economic differences as access to individual transportation is dominantly a matter of income. Consequently, in some instances modal choice is more a modal constraint linked to economic opportunities. In central locations, there are generally few transport availability problems because private and public transport facilities are present. However, in locations outside the central core that are accessible only by the automobile, a significant share of the population is isolated if it does not own an automobile. Limited public transit and high automobile ownership costs have created a class of spatially constrained (mobility deprived) people. They do not have access to the services in the suburbs, but more importantly to the jobs that are increasingly concentrated in those areas. 3. Urban Transit

The main reason why people use public transit is because they cannot effectively park their car where they would like to go.

Transit is dominantly 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 public service, it potentially benefits from economies of agglomeration related to high densities and from economies of scale related to high mobility demands. The lower the density in which a transit system is operating, the lower the demand, with the greater likelihood that it will be run at a loss. In fact, the great majority of 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. 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 as in a declining market there were limited incentives to invest. Gradually, they were purchased by public interests and incorporated into large agencies, mainly for the sake of providing mobility. As such, public transit often serves more a social function of public service and a tool of social equity than having any sound 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) 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 transit systems:

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.

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 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. 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 has the relative share of public transit ridership is declining across the board. Community 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. Related Topics Transportation and the Urban Form Urban Land Use and Transportation Urban Transport Problems City Logistics Traffic Counts and Traffic Surveys

Media Omnibus, London, Late 19th Century The Street Car / Tram

(Lisbon, Portugal) Transit Technology and Urban Development, Late 19th – Early

20th Century Suitability of Travel Modes Types of Urban Movements

Share of Cycling over the Total Amount of Trips, mid 1990s Income

and Urban Transport Demand Main Purposes of Urban Trips Typical

Urban Day Trips by Modes, Origins and Destinations Urban Travel by Purpose and

by Time of the Day Time of Departure for Home to Work Trips, United States

Typical Truck Trips Distribution by Time of the Day Modal Split for

Global Cities, 1995 Home-to-Work Trips Modes, United States, 1985-2005

Accessibility to Employment in Urban Areas Annual VMT by Age

Group and Gender, United States, 1995 Destination for Work-Related Movements in

the United States Public Transport Market Share in the United States, 1900-2005

Components of an Urban Transit System Private Vehicle and Public

Transport Market Share, 1990/91 Trips by Public Transport in the United States,

1970-2005 Transit and Urban Form Transit and Urban Land Use

Impacts Accessibility along a Transit Line Home | Contents | Media | Glossary | Links | About | Contact | Purchase Copyright © 1998-2012, Dr. Jean-Paul Rodrigue, Dept. of Global Studies & Geography , Hofstra University, New York, USA.This material (including graphics) cannot be copied or redistributed, in whole or in part, in ANY FORM (printed or electronic) and on ANY MEDIA. For specific uses permission MUST be requested and the material must be cited.

THE GEOGRAPHY OF TRANSPORT SYSTEMS

Home Contents

o Table of Contents o Chapter 1 - Transportation and Geography o Chapter 2 - Transportation and the Spatial Structure o Chapter 3 - Transportation Modes o Chapter 4 - Transport Terminals o Chapter 5 - International Trade and Freight Distribution o Chapter 6 - Urban Transportation o Chapter 7 - Transportation and the Economy o Chapter 8 - Transport, Energy and Environment o Chapter 9 - Transport Planning and Policy o Appendix - Methods in Transport Geography

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SECOND EDITIONJean-Paul Rodrigue, Claude Comtois and Brian Slack (2009), New York: Routledge, 352 pages.

ISBN 978-0-415-48324-7 Home > Contents > Chapter 6 > Concept 2Urban Land Use and Transportation Author: Dr. Jean-Paul Rodrigue 1. The Land Use - Transport System Urban land use comprises two elements; the nature of land use which relates to which activities are taking place where, and the level of spatial accumulation, which indicates their intensity and concentration. Central areas have a high level of spatial accumulation and corresponding land uses, such as retail, while peripheral areas have lower levels of accumulation. Most economic, social or cultural activities imply a multitude of functions, such as production, consumption and distribution. These functions take place at specific locations and are part of an activity system. Some are routine activities, because they occur regularly and are thus predictable, such as commuting and shopping. Others are institutional activities that tend to be irregular, and are shaped by lifestyle (e.g. sports and leisure) or by special needs (e.g. healthcare). Others are production activities that are related to manufacturing and distribution, whose linkages may be local, regional or global. The behavioral patterns of individuals, institutions and firms have an imprint on land use in terms of their locational choice. The representation of this imprint requires a typology of land use, which can be formal or functional: Formal land use representations are concerned with qualitative attributes of space such as its form, pattern and aspect and are descriptive in nature.Functional land use representations are concerned with the economic nature of activities such as production, consumption, residence, and transport, and are mainly a socioeconomic description of space.

At the global level, cities consume about 3% of the total land mass. Although figures can vary considerably depending on the city, residential land use is the most common, occupying between 65 and 75% of the surface of a city. Commercial and industrial land uses occupy 5-15% and 15-25% of the surface respectively. Land use, both in formal and functional representations, implies a set of relationships with other land uses. For instance, commercial land use involves relationships with its supplier and customers. While relationships with suppliers will dominantly be related with movements of freight, relationships with customers would include movements of

people. Thus, a level of accessibility to both systems of circulation must be present. Since each type of land use has its own specific mobility requirements, transportation is a factor of activity location, and is therefore associated intimately with land use. Within an urban system each activity occupies a suitable, but not necessarily optimal location, from which it derives rent. Transportation and land use interactions mostly consider the retroactive relationships between activities, which are land use related, and accessibility, which is transportation related. These relationships have often been described as a classic "chicken-and-egg" problem since it is difficult to identify the triggering cause of change; do transportation changes precede land use changes or vice-versa? There is a scale effect at play as large infrastructure projects tend to precede and trigger land use changes while small scale transportation projects tend to complement the existing land use pattern. Further, the expansion of urban land uses takes place over various circumstances such as infilling (near the city center) or sprawl (far from the city center) and where in each case transportation plays a different role. Urban transportation aims at supporting transport demands generated by the diversity of urban activities in a diversity of urban contexts. A key for understanding urban entities thus lies in the analysis of patterns and processes of the transport / land use system. This system is highly complex and involves several relationships between the transport system, spatial interactions and land use:

Transport system. Considers the set of transport infrastructures and modes that support urban movements of passengers and freight. It generally expresses the level of accessibility.

Spatial interactions. Consider the nature, extent, origins and destinations of the urban movements of passengers and freight. They take into consideration the attributes of the transport system as well as the land use factors that are generating and attracting movements.

Land use. Considers the level of spatial accumulation of activities and their associated levels of mobility requirements. Land use is commonly linked with demographic and economic attributes.

A conundrum concerns the difficulties of linking a specific mode of transportation with specific land use patterns. While public transit systems tend to be associated with higher densities of residential and commercial activities and highways with lower densities, the multiplicity of modes available in urban areas, including freight distribution, conveys an unclear and complex relationship. 2. Urban Land Use Models The relationships between transportation and land use are rich in theoretical representations that have contributed much to regional sciences. Since transportation is a distance-decay altering technology, spatial organization is assumed to be strongly influenced by the concepts of location and distance. Several descriptive and analytical models of urban land use have been developed over time, with increased levels of complexity. All involve some consideration of transport in the explanations of urban land use structures. The following is a non-exhaustive categorization:

Central places and concentric land uses. Von Thunen’s regional land use model is the oldest representation based on a central place, the market town, and its concentric impacts on surrounding land uses. It was initially developed in the early 19th century (1826) for the analysis of agricultural land use patterns in Germany. It used the concept of economic rent to explain a spatial organization where different agricultural activities

are competing for the usage of land. The underlying principles of this model have been the foundation of many others where economic considerations, namely land rent and distance-decay, are incorporated. The core assumption of the model is that agricultural land use is patterned in the form of concentric circles around a market that consumes all the surplus production, which must be transported. Many concordances of this model with reality have been found, notably in North America.

Concentric urban land uses. The Burgess concentric model was among the first attempts to investigate spatial patterns at the urban level (1925). Although the purpose of the model was to analyze social classes, it recognized that transportation and mobility were important factors behind the spatial organization of urban areas. The formal land use representation of this model is derived from commuting distance from the central business district, creating concentric circles. Each circle represents a specific socioeconomic urban landscape. This model is conceptually a direct adaptation of the Von Thunen's model to urban land use since it deals with a concentric representation. Even close to one century after the concentric urban model was designed, spatial changes in Chicago are still reflective of such a process.

Polycentric and zonal land uses. Sector and multiple nuclei land use models were developed to take into account numerous factors overlooked by concentric models, namely the influence of transport axis (Hoyt, 1939) and multiple nuclei (Harris and Ullman, 1945) on land use and growth. Both representations consider the emerging impacts of motorization on the urban spatial structure. Such representations also considered that transportation infrastructures, particularly terminals such as rail stations or ports, occupy specific locations and can be considered as land uses.

Hybrid land uses. Hybrid models are an attempt to include the concentric, sector and nuclei behavior of different processes in explaining urban land use. They are an attempt to integrate the strengths of each approach since none of these appear to provide a completely satisfactory explanation. Thus, hybrid models, such as that developed by Isard (1955), consider the concentric effect of central locations (CBDs and sub-centers) and the radial effect of transport axis, all overlain to form a land use pattern. Also, hybrid representations are suitable to explain the evolution of the urban spatial structure as they combine different spatial impacts of transportation on urban land use, let them be concentric or radial, and this at different points in time.

Land use market. Land rent theory was also developed to explain land use as a market where different urban activities are competing for land usage at a location. It is strongly based in the market principle of spatial competition where actors are bidding to secure and maintain their presence at a specific location. The more desirable a location is, the higher its rent value. Transportation, through accessibility and distance-decay, is a strong explanatory factor on the land rent and its impacts on land use. However, conventional representations of land rent leaning on the concentric paradigm are being challenged by structural modifications of contemporary cities.

Cellular automata. Dynamic land use representations developed on the principle that space can be represented as a grid where each cell is a discrete land use unit. Cell states thus symbolize land uses and transition rules express the likelihood of a change from one land use state to another. Because cells are symbolically connected and interrelated (e.g. adjacency), models can be used to investigate the dynamics, evolution, and self-organization of cellar automata land use systems. The cellular approach enables to

achieve a high level of spatial detail (resolution) and realism, as well as to link the simulation directly to visible outcomes on the regional spatial structure. They are also readily implementable since Geographic Information Systems are designed to work effectively with grid-based spatial representations.

Cellular automata improves upon most transportation - land use models that are essentially static as they explain land use patterns, but they do not explicitly consider the processes that are creating or changing them. The applicability and dynamics of land use models is related to issues such as the age, size and the locational setting of a city. For instance, concentric cities are generally older and of smaller size, while polycentric cities are larger and relate to urban development processes that took place more recently. While most of the conceptual approaches related to transportation and land use relationships have been developed using empirical evidence related to North America and Western Europe, this perspective does not necessarily apply to other parts of the world. 3. Transportation and Urban Dynamics Both land use and transportation are part of a dynamic system that is subject to external influences. Each component of the system is constantly evolving due to changes in technology, policy, economics, demographics and even culture or values. As a result, the interactions between land use and transportation are played out as the outcome of the many decisions made by residents, businesses and governments. The field of urban dynamics has expended the scope of conventional land use models, which tended to be descriptive, by trying to consider relationships behind the evolution of the urban spatial structure. This has led to a complex modeling framework including a wide variety of components. Among the concepts supporting urban dynamics representations are retroactions, whereby one component changes it influences others. The changes will influence the initial component back, either positively or negatively. The most significant components of urban dynamics are:

Land use. This is the most stable component of urban dynamics, as changes are likely to modify the land use structure over a rather long period of time. This comes as little surprise since most real estate is built to last at least several decades. The main impact of land use on urban dynamics is its function of a generator and attractor of movements.

Transport network. This is also considered to be a rather stable component of urban dynamics, as transport infrastructures are built for the long term. This is particularly the case for large transport terminals and subway systems that can operate for a very long period of time. For instance, many railway stations are more than one hundred years old. The main contribution of the transport network to urban dynamics is the provision of accessibility. Changes in the transport network will impact accessibility and movements.

Movements. The most dynamic component of the system since movements of passengers or freight reflect almost immediately changes. Movements thus tend more to be an outcome of urban dynamics than a factor shaping them.

Employment and workplaces. They account for significant inducement effects over urban dynamics since many models often consider employment as an exogenous factor. This is specifically the case for employment that is categorized as basic, or export oriented, which is linked with specific economic sectors such as manufacturing. Commuting is a direct outcome of the number of jobs and the location of workplaces.

Population and housing. They act as the generators of movements, because residential areas are the sources of commuting. Since there are a wide array of incomes, standards of living, preferences and ethnicity, this diversity is reflected in the urban spatial structure.

The issue about how to articulate these relations remains, particularly in the current context of interdependency between local, regional and global processes. Globalization has substantially blurred the relationships between transportation and land use as well as its dynamics. The main paradigm is concerned with the point that factors once endogenous to a regional setting become exogenous. Consequently, many economic activities that provide employment and multiplying effects, such as manufacturing, are driven by forces that are global in scope and may have little to do with regional dynamics. For instance, capital investment could come from external sources and the bulk of the output could be bound to international markets. In such a context it would be difficult to explain urban development processes taking place in coastal Chinese cities, or in a region such as the Pearl River Delta, since export oriented strategies are among the most significant driving forces. Looking at the urban dynamics of such a system from an endogenous perspective would fail to capture driving forces that are dominantly exogenous. Related Topics Transportation and the Urban Form Transportation / Land Use Modeling Urban Mobility Urban Transport Problems Transportation, Land Use and the Environment Transport and Spatial Organization Transport and Location

Media

Activity Systems and Land Use

Formal and Functional Land Use Relationships between Land Uses

Transport Infrastructure and Activity Location Transportation / Land Use

Relationships Land Use and Transportation Interactions Types of Urban

Expansion Von Thunen's Regional Land Use Model Inference of Von

Thunen’s Model to Continental United States The Burgess Urban Land Use Model

Population Density Changes by Census Block, Chicago 2000-2010

Sector and Nuclei Urban Land Use Representations Hybrid Land Use

Representation Transportation and the Constitution of Urban Landscapes

Land Economics Land Rent Theory and Rent Curve Land

Rent and Land Use Contemporary Modifications of the Land Rent Theory

Cellular Automata Land Use Dynamics Basic Urban Dynamics

Dynamics of Urban Change China's Special Economic Zones  Home | Contents | Media | Glossary | Links | About | Contact | Purchase Copyright © 1998-2012, Dr. Jean-Paul Rodrigue, Dept. of Global Studies & Geography , Hofstra University, New York, USA.This material (including graphics) cannot be copied or redistributed, in whole or in part, in ANY FORM (printed or electronic) and on ANY MEDIA. For specific uses permission MUST be requested and the material must be cited.

THE GEOGRAPHY OF TRANSPORT SYSTEMS

Home Contents

o Table of Contents o Chapter 1 - Transportation and Geography o Chapter 2 - Transportation and the Spatial Structure o Chapter 3 - Transportation Modes

o Chapter 4 - Transport Terminals o Chapter 5 - International Trade and Freight Distribution o Chapter 6 - Urban Transportation o Chapter 7 - Transportation and the Economy o Chapter 8 - Transport, Energy and Environment o Chapter 9 - Transport Planning and Policy o Appendix - Methods in Transport Geography

media Glossary links About

SECOND EDITIONJean-Paul Rodrigue, Claude Comtois and Brian Slack (2009), New York: Routledge, 352 pages.

ISBN 978-0-415-48324-7 Home > Contents > Chapter 6 > Concept 1Transportation and the Urban Form Author: Dr. Jean-Paul Rodrigue 1. Global Urbanization No discussion about the urban spatial structure can take place without an overview of urbanization, which has been one of the dominant trends of economic and social change of the 20th century, especially in the developing world. Urbanization. The process of transition from a rural to a more urban society. Statistically, urbanization reflects an increasing proportion of the population living in settlements defined as urban, primarily through net rural to urban migration. The level of urbanization is the percentage of the total population living in towns and cities while the rate of urbanization is the rate at which it grows (UNFPA, 2007).This transition is expected to go on well into the second half of the 21st century, a trend reflected in the growing size of cities and in the increasing proportion of the urbanized population. Urban mobility problems have increased proportionally, and in some cases exponentially, with urbanization since it concentrates mobility demands over a specific area. Since 1950, the world's

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urban population has more than doubled, to reach nearly 3.5 billion in 2010, about 50.6% of the global population. This is the outcome of three main demographic trends:

Natural increase. It is simply the outcome of more births than deaths in urban areas, a direct function of the fertility rate as well as the quality of healthcare systems (lower mortality rates, particularly for infants). Phases in the demographic transition are commonly linked with urbanization rates. Although this factor played an important role in the past, it is of much lesser importance today as fertility rates in many developed countries have dropped significantly, in some cases like Western Europe, Japan and South Korea below replacement rate.

Rural to urban migrations. This has been a strong factor of urbanization, particularly in the developing world where migration accounted between 40 and 60% of the urban growth. Such a process has endured since the beginning of the industrial revolution in the 19th century, first in the developed world and then in the developing world. The reasons for urban migration are numerous and may involve the expectation to find employment, improved agricultural productivity which frees rural labor or even political and environmental problems where populations are constrained to leave the countryside.

International migration. The growth in international migration has been an important factor in the urbanization of major gateway cities, such as Los Angeles, Miami, New York, London and Paris. This process has a tendency to take place in the largest cities, but there is a trickle down to cities of smaller size.

Fundamental changes in the socio-economic environment of human activities as urbanization involves new forms of employment, economic activity and lifestyle have been observed. Thus, industrialization in the developing world is directly correlated with urbanization, the case of China being particularly eloquent. The industrialization of coastal China has led to the largest rural to urban migration in history. According to the United Nations Population Fund, about 18 million people migrate from rural areas to cities each year in China alone. Current global trends indicate a growth of about 50 million urbanites each year, roughly a million a week. More than 90% of that growth occurs in developing countries which places intense pressures on urban infrastructures, particularly transportation, to cope (see Concept 4). By 2050, 6.4 billion people, about two thirds of humanity, are likely to be urban residents. What can be considered as urban includes a whole continuum of urban spatial structures, ranging from small towns to large urban agglomerations. This also brings the question about optimal city size since technical limitations (road, utilities) are not much an impediment in building very large cities. Many of the world's largest cities can be labeled as dysfunctional mainly because as city size increases the rising complexities are not effectively coped with managerial expertise. 2. The Urban Form Demographic and mobility growth have been shaped by the capacity and requirements of urban transport infrastructures, such as roads, transit systems or simply walkways. Consequently, there is a wide variety of urban forms, spatial structures and associated urban transportation systems. Urban form. Refers to the spatial imprint of an urban transport system as well as the adjacent physical infrastructures. Jointly, they confer a level of spatial arrangement to cities.Urban (spatial) structure. Refers to the set of relationships arising out of the urban form and its underlying interactions of people, freight and information. It tries to evaluate to what extent specific urban structures can be achieved with specific transport systems.

In light of transport developments, the urban spatial structure can be categorized by its level of centralization and clustering:

Centralization. Refers to the setting of activities in relation to the whole urban area. A centralized city has a significant share of its activities in its center while a decentralized city does not. Large employers such as financial institutions are the main drivers of centralization.

Clustering. Refers to the setting of activities in relation to a specific part of the urban area. A cluster of activities is therefore a concentration around a specific focal point, which tend to be transport infrastructures such as an highway interchange, a transit terminal or a smaller town that has been absorbed by the expansion of the metropolis.

Even if the geographical setting of each city varies considerably, the urban form and its spatial structure are articulated by two structural elements:

Nodes. These are reflected in the centrality of urban activities, which can be related to the spatial accumulation of economic activities or to the accessibility to the transport system. Terminals, such as ports, train station, railyards, and airports, are important nodes around which activities agglomerate at the local or regional level. Nodes have a hierarchy related to their importance and contribution to urban functions, with high order nodes such as management and retailing and lower order nodes such as production and distribution.

Linkages. These are the infrastructures supporting flows from, to and between nodes. The lowest level of linkages includes streets, which are the defining elements of the urban spatial structure. There is a hierarchy of linkages moving up to regional roads and railways and international connections by air and maritime transport systems.

Depending on their nature, urban nodes and linkages provide for a functional connectivity, implying interdependent urban functions related to trade, production and telecommunications. Urban transportation is thus associated with a spatial form which varies according to the modes being used. What has not changed much is that cities tend to opt for a grid street pattern. This was the case for many Roman cities built in the 1st century as it was for American cities built in the 20th century. The reasons behind this permanence are relatively simple; a grid pattern jointly optimizes accessibility and available real estate. Obviously, many cities are not organized as a grid. They correspond to older cities, many former fortified towns, as well as cities which grew from a constrained location such as an island or a river junction. Local geographical and historical characteristics remain important influences on the urban form. In an age of motorization and personal mobility, an increasing number of cities are developing a spatial structure that increases reliance on motorized transportation, particularly the privately owned automobile. This has incited a shift from a grid pattern towards curvilinear and cul-de-sac patterns that are commonly found in suburban areas. Dispersion, or urban sprawl, is taking place in many different types of cities, from dense, centralized European metropolises such as Madrid, Paris, and London, to rapidly industrializing metropolises such as Seoul, Shanghai, and Buenos Aires, to those experiencing recent, fast and uncontrolled urban growth, such as Mumbai and Lagos. Recent urban expansion is consequently almost all geared towards the automobile. 3. Evolution of Transportation and Urban Form Historically, movements within cities tended to be restricted to walking, which made medium and long distance urban linkages rather inefficient

and time-consuming. Thus, activity nodes tended to be agglomerated and urban forms compact. Many modern cities have inherited an urban form created under such circumstances, even though they are no longer prevailing. The dense urban cores of many European, Japanese and Chinese cities, for example, enable residents to make between one third and two thirds of all trips by walking and cycling. At the other end of the spectrum, the dispersed urban forms of most Australian, Canadian and American cities, which were built recently, encourages automobile dependency and are linked with high levels of mobility. Many major cities are also port cities with maritime accessibility playing an enduring role not only for the economic vitality but also in the urban spatial structure with the port district being an important node. Airports terminals have also been playing a growing role in the urban spatial structure as they can be considered as cities within cities. The evolution of transportation has generally led to changes in urban form. The more radical the changes in transport technology have been, the more the alterations on the urban form. Among the most fundamental changes in the urban form is the emergence of new clusters expressing new urban activities and new relationships between elements of the urban system. In many cities, the central business district (CBD), once the primary destination of commuters and serviced by public transportation, has been changed by new manufacturing, retailing and management practices. Whereas traditional manufacturing depended on centralized workplaces and transportation, technological and transportation developments rendered modern industry more flexible. In many cases, manufacturing relocated in a suburban setting, if not altogether to entirely new low cost locations offshore. Retail and office activities are also suburbanizing, producing changes in the urban form. Concomitantly, many important transport terminals, namely port facilities and railyards, have emerged in suburban areas following new requirements in modern freight distribution brought in part by containerization. The urban spatial structure shifted from a nodal to a multi-nodal character. Initially, suburban growth mainly took place adjacent to major road corridors, leaving a plots of vacant or farm land in between. Later, intermediate spaces were gradually filled up, more or less coherently. Highways and ring roads, which circled and radiated from cities, favored the development of suburbs and the emergence of important sub-centers that compete with the central business district for the attraction of economic activities. As a result, many new job opportunities have shifted to the suburbs (if not to entirely new locations abroad) and the activity system of cities has been considerably modified. Different parts of a city have different dynamism depending on its spatial pattern. These changes have occurred according to a variety of geographical and historical contexts, notably in North America and Europe as each subsequent phase of urban transportation developments led to different spatial structures. Sometimes, particularly when new modern urban road infrastructures are built, the subsequent changes in the urban form can be significant. In addition, a variety of density gradients are observed in different cities around the world. The differences are particularly prevalent between North American and European cities. Two processes had a substantial impact on contemporary urban forms:

Dispersed urban land development patterns have been dominant in North America over the last 50 years, where land is abundant, transportation costs were low, and where the economy became dominated by tertiary and quaternary activities. Under such circumstances, it is not surprising to find that there is a strong relationship between urban density and automobile use. For many cities their built up areas have grown at a faster rate than their populations. In addition, commuting became relatively inexpensive compared with land costs, so households had an incentive to buy lower-priced housing at

the urban periphery. Similar patterns can be found in many European cities, but this change is occurring at a slower pace and involving a smaller range.

The decentralization of activities resulted in two opposite effects. First, commuting time has remained relatively stable in duration. Second, commuting increasingly tends to be longer and made by using the automobile rather than by public transit. Most transit and road systems were developed to facilitate suburb-to-city, rather than suburb-to-suburb, commuting. As a result, suburban highways are often as congested as urban highways.

Although transportation systems and travel patterns have changed considerably over time, one enduring feature remains that most people travel between 30-40 minutes in one direction. Globally, people are spending about 1.2 hours per day commuting, wherever this takes place in a low or a high mobility setting. Different transport technologies, however, are associated with different travel speeds and capacity. As a result, cities that rely primarily on non-motorized transport tend to be different than auto-dependent cities. Transport technology thus plays a very important role in defining urban form and the spatial pattern of various activities. Still, the evolution of the urban form is path dependent, implying that the current spatial structure is obviously the outcome of past developments, but that those developments were strongly related to local conditions involving to the setting, physical constraints and investments in infrastructures and modes. 4. The Spatiality of Urban Transportation The amount of urban land allocated to transportation is often correlated with the level of mobility. In the pre-automobile era, about 10% of the urban land was devoted to transportation which were simply roads for a dominantly pedestrian traffic. As the mobility of people and freight increased, a growing share of urban areas was allocated to transport and the infrastructures supporting it. Large variations in the spatial imprint of urban transportation are observed between different cities as well as between different parts of a city, such as between central and peripheral areas. The major components of the spatial imprint of urban transportation are:

Pedestrian areas. Refer to the amount of space devoted to walking. This space is often shared with roads as sidewalks may use between 10% and 20% of a road's right of way. In central areas, pedestrian areas tend to use a greater share of the right of way and in some instances, whole areas are reserved for pedestrians. However, in a motorized context, most pedestrian areas are for servicing people's access to transport modes such as parked automobiles.

Roads and parking areas. Refer to the amount of space devoted to road transportation, which has two states of activity; moving or parked. In a motorized city, on average 30% of the surface is devoted to roads while another 20% is required for off-street parking. This implies for each car about 2 off-street and 2 on-street parking spaces. In North American cities, roads and parking lots account between 30 and 60% of the total surface.

Cycling areas. In a disorganized form, cycling simply shares access to pedestrian and road space. However, many attempts have been made to create spaces specifically for bicycles in urban areas, with reserved lanes and parking facilities. The Netherlands has been particularly proactive over this issue with biking paths parts of the urban transport system; 27% of the total amount of commuting is accounted by cycling.

Transit systems. Many transit systems, such as buses and tramways, share road space with automobiles, which often impairs their respective efficiency. Attempts to mitigate

congestion have resulted in the creation of road lanes reserved to buses either on a permanent or temporary (during rush hour) basis. Other transport systems such as subways and rail have their own infrastructures and, consequently, their own rights of way.

Transport terminals. Refer to the amount of space devoted to terminal facilities such as ports, airports, transit stations, railyards and distribution centers. Globalization has increased the mobility of people and freight, both in relative and absolute terms, and consequently the amount of urban space required to support those activities. Many major terminals are located in the peripheral areas of cities, which are the only locations where sufficient amounts of land is available.

The spatial importance of each transport mode varies according to a number of factors, density being the most important. If density is considered as a gradient, rings of mobility represent variations in the spatial importance of each mode at providing urban mobility. Further, each transport mode has unique performance and space consumption characteristics. The most relevant example is the automobile. It requires space to move around (roads) but it also spends 98% of its existence stationary in a parking space. Consequently, a significant amount of urban space must be allocated to accommodate the automobile, especially when it does not move and is thus economically and socially useless. In large urban agglomerations close to all the available street parking space in areas of average density and above is occupied throughout the day. At an aggregate level, measures reveal a significant spatial imprint of road transportation among developed countries. In the United States, more land is thus used by the automobile than for housing. In Western Europe, roads account for between 15% and 20% of the urban surface while for developing countries, this figure is about 10% (6% on average for Chinese cities). 5. Transportation and the Urban Structure Urbanization involves an increased numbers of trips in urban areas. Cities have traditionally responded to growth in mobility by expanding the transportation supply, by building new highways and transit lines. In the developed world, that has mainly meant building more roads to accommodate an ever-growing number of vehicles. Several urban spatial structures have accordingly emerged, with the reliance on the automobile being the most important discriminatory factor. Four major types can be identified at the metropolitan scale:

Type I - Completely Motorized Network : Representing an automobile-dependent city with a limited centrality and dispersed activities.

Type II - Weak Center : Representing the spatial structure of many American cities where many activities are located in the periphery.

Type III - Strong Center : Representing high density urban centers with well developed public transit systems, particularly in Europe and Asia.

Type IV - Traffic Limitation . Representing urban areas that have implemented traffic control and modal preference in their spatial structure. Commonly, the central area is dominated by public transit.

There are different scales where transportation systems influence the structure of communities, districts and the whole metropolitan area. For instance, one of the most significant impacts of transportation on the urban structure has been the clustering of activities near areas of high accessibility. The impact of transport on the spatial structure is particularly evident in the

emergence of suburbia. Although many other factors are important in the development of suburbia, including low land costs, available land (large lots), the environment (clean and quiet), safety, and car-oriented services (shopping malls), the spatial imprint of the automobile is dominant. Even if it could be argued that roads and the automobile have limited impacts on the extent of urban spraw, they are a required condition for sprawl to take place. While it is difficult to assess in which specific circumstances the first suburbs emerged, suburban developments have occurred in many cities worldwide, although no other places have achieved such a low density and automobile dependency than in the North America. The automobile is also linked with changes in street layouts. While older parts of cities tend to have a conventional grid layout, from the 1930s new suburbs started to be designed in a curvilinear fashion, which included some cul-de-sacs (dead ends). By the 1950s, the prevailing design for new suburbs was privileging cul-de-sacs. Although the aim was to create a more private and safe environment, particularly in cul-de-sac sections, the outcome was also a growing sense of isolation and car use. Facing the expansion of urban areas, congestion problems and the increasing importance of inter-urban movements the existing structure of urban roads was judged to be inadequate. , several ring roads have been built around major cities. They became an important attribute of the spatial structures of cities, notably in North America. Highway interchanges in suburban areas are notable examples of new clusters of urban development. The extension (and the over-extension) of urban areas have created what may be called peri-urban areas. They are located well outside the urban core and the suburbs, but are within reasonable commuting distances; the term "edge cities" has been used to label a cluster of urban development taking place in a suburban settings. Related Topics Urban Land Use and Transportation Urban Mobility Urban Transport Problems Transport and Spatial Organization Transport and Location The Function of Transport Terminals Transportation, Land Use and the Environment

Media World Urban Population, 1950-2005 with Projections to 2020

Demographic Transition Cities with more than 10 million Inhabitants

World's Largest Cities World at Night Urban Population (in 1,000s) and

Percentage of Urban Population per Continent, 1950-2030 Perspectives about the

Urban Spatial Structure: From Dichotomy to Continuum Transportation, Urban

Form and Spatial Structure Types of Urban Spatial Structures Nodes,

Linkages and Urban Form Cities and Connectivity One Hour

Commuting According to Different Urban Transportation Modes Evolution of the

Spatial Structure of a City Street Network Types Possible Urban

Movement Patterns Evolution of Transportation and Urban Form in North American

and European Cities Evolution of Urban Densities in North America and Europe

Access Ramp to the Nanpu Bridge, Shanghai Population Density by

Distance from City Center, Selected Cities Population Density Changes by Census

Block, Chicago 2000-2010 Density and Car Use in North American Cities, 1991

Average Journey to Work Travel Time, 1990 Service Attributes of

Urban Transport Modes Pedestrian, Cycling and Road Spaces, Amsterdam,

Netherlands Share of Cycling over the Total Amount of Trips, mid 1990s

Rings of Mobility Performance of Urban Transport Modes Land Area

Consumed by the Car in Selected Countries, 1999 The Rationale of a Ring Road

Type I - Completely Motorized Network Type II - Weak Center

Type III - Strong Center Type IV - Traffic Limitation Scale

and Urban Spatial Structure Suburban Development along an Highway Interchange Home | Contents | Media | Glossary | Links | About | Contact | Purchase Copyright © 1998-2012, Dr. Jean-Paul Rodrigue, Dept. of Global Studies & Geography , Hofstra University, New York, USA.This material (including graphics) cannot be copied or redistributed, in whole or in part, in ANY FORM (printed or electronic) and on ANY MEDIA. For specific uses permission MUST be requested and the material must be cited.