csdCenter for Sustainable Development

Sustainable Transportation

Nina Wilson

Editor

Werner LangAurora McClain

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Introduction

Sustainable transportation, or sustainable mobility and green transportation, refers to the mobility system that meets people’s access needs and supports a vital economy but does not endanger public health or ecosystem. The progress of sustainable transportation is inex-tricably tied to the complexities of city develop-ment, including environmental, technological, social, and economic conditions. Achieving transportation sustainability is no easy task; it requires long-term commitments from indi-vidual users and from the society as a whole. Issues of importance in the context of this study include: mobility demand and supply; car dependence and its far-ranging ramifications (e.g. emissions, energy consumption, and con-gestion); and planning and design strategies to achieving sustainable transportation.

Mobility demand and supply

Mobility demand is driven by four fundamental factors: income growth, evolving demographic conditions, changes in urban structure (such as urbanization or suburbanization), and technological developments, which influence means and speeds of travel or enable tele-communications. These factors are closely tied with the level of development that countries are currently undergoing.

Income growth results in increased rates of travel and a rising value placed on time. Demographics play a role as well: total and urbanized population, increasing participation of women in the labor force, and decreas-ing average household size contribute to this need. Changes in urban structure impact levels of mobility, as do the increasingly com-plex relational patterns of urban and suburban areas of large metropolitan areas. Technol-ogy, and more specifically, the way in which it affects means of travel, is also important in the equation. For example, telecommunica-tions technologies have enabled commuters to conference, meet, and work remotely, a feature that has reduced the absolute neces-sity for traveling to distant locations to conduct many business operations. Motorization, rising with income, has also affected countries in Asia such as Japan, Singapore, Korea, and Hong Kong. Legislative solutions are presently the most viable strategies used to address the issue, but the demand of urban areas with populations exceeding ten million presents the greatest travel need, and poses the most complex problem.

In most developed countries, growing travel demand has led to a strong dependence on private cars. Car dependence describes the problematic phenomenon of excessive vehicle use and the environmental and social costs associated with it. Increased traffic congestion and emissions are a by-product of this activity.

Sustainable Transportation

Nina Wilson

Based on a presentation by Ming Zhang, Ph.D

Figure 1: Dallas Area Rapid Transit Mockingbird Station

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In the developing countries, meeting the basic mobility needs is a challenge facing the urban and rural residents. Rapid urbanization and motorization in many fast-growing cities cause transportation problems as the under-supplied transportation infrastructure cannot keep up with the growth in travel demand.

Evolution of transportation

The speed of major modes of transportation arrived at a plateau in the United States in the 1950s and 1960s. Daily travel patterns from 1969 to 2000 showed a decrease in transit use, and increases in automobile use, walk-ing, and biking. Auto ownership in developed western nations such as the United States, Italy, and Germany rose over this period, while developing nations used public transit comparatively more. According to Peter Lou-kopoulos,5 the unabated increase in car traffic witnessed in recent years in the industrialized world has led to a focus on demand-based traffic-restriction measures, in contrast to the usual supply-based measures. The great-est increase in ownership in this time frame occurred in the United States, rising from ap-proximately 350 in 1960 to almost 700 in 1995. Italy followed closely and experienced a more extreme fluctuation, starting at 40 in 1960 and rising to 550 by 1995. Automobile use patterns corresponded closely with those of ownership, resulting in a similar pattern.

After World War II, roadway capacities expand-ed significantly in the United States. Capacity expansion, however, proves not a sustainable solution to roadway congestion as explained by Anthony Downs’s Law of Triple Conver-gence. The theory is threefold, composed of spatial, temporal, and modal changes. Spatial change includes the convergent movement of traffic from other parts of the city. The temporal condition translates to a switch that travelers make, from using roads at non-peak times to peak times. Finally, the modal change sees

travelers shift from a non-driving to a driving strategy of movement. Costs of congestion Fundamental changes in infrastructure, such as the widening of a vehicular thoroughfare, affect traffic congestion levels beyond the scope of the impact that motorists have when they decide where, when, and how to drive. Instead, a larger cycle of congestion is initiated by such changes, begun by higher spatial capacity for traffic. Movement becomes easier, which results in increased urban sprawl. As more people move further out from the city center, the length of movement increases. Subsequently, the quantity of movements multiply, which finally reproduces the initial problem of congestion. Thus, the practice of simply expanding highway capacity to solve traffic problems is an unsustainable strategy. Evidence which illustrates increases in con-gestion can be found by looking at the conges-tion index, which is a measure produced by the Thoreau Institute that expresses a direct comparison of miles traveled with the miles of road available to travel on. Los Angeles and Chicago have the highest congestion index, 1.50 and 1.47 respectively, with Chicago hav-ing experienced the greatest change between 1982 and 2005, from 1.12 to 1.47. The costs associated with these high levels of congestion range from Seattle’s $1.4 million per year to $9.3 million for Los Angeles, when comparing large urban areas in 2005. Austin shows the highest cost for a medium-sized urban area at $4.2 million, and Tulsa is at the bottom of the list, costing $1.2 million. Aggregate congestion costs for all areas total $78 million dollars per year. Energy consumption The United States accounts for 5% of the world’s population, but consumes 26% of the

world’s petroleum. In 2000, the U.S. consumed 19.7 mmbpd (million barrels per day) of pe-troleum and petroleum products. Of this total, 10.42 mmbpd were imported. In 2007, the U.S. imported 12.04 mmbpd of petroleum. The transportation sector consumes 65% of petro-leum products. The automobile is the biggest consumer of energy within the transportation sector. Automobile use alone accounts for 40% of all oil consumption in the U.S. According to “Conserving Energy and Preserving the Environment: The Role of Public Transporta-tion,” a study published by the American Public Transportation Association in 2002, if Ameri-cans used public transportation for 10 percent of their daily travel, the nation could reduce its dependence on imported oil by more than 40%, which is nearly equal to the energy used to produce food in the United States.1

Environmental impacts of excessive driving occur at different scales, in various ways. At the local level, noise pollution, visual chaos, and heat island effects occur. About 60% of the pollutants are transportation-related. Most comes from private vehicles. Impacts on natural environment include those affecting water resources, wetlands, plant and animal life. Impacts on the global environment include greenhouse gas emissions. In the U.S., transportation accounts for 33% of total GHG emissions. Of this 33%, cars are responsible for 60%, trucks another 15%, and ships, air-craft, etc., the remainder. Greenhouse gases are composed of approximately 95% carbon dioxide. Environmental impacts are also mea-sured through the intensity of various modes of transport, measured in Btu per VMT (Vehicle Miles Travelled) based on averages of calories and vehicle fuel usage. The mode of trans-portation with the highest intensity is trucks, followed by rail transit, automobile, and buses. Fuel and energy solutions potentially rest in the technological realm, with ICE, hybrid, and in the future, fuel cell, engine technologies. Alternatively, policy-based solutions may be

Figure 2: Freeways in Los Angeles FIgure 4: Bicycles used for transportation in ShanghaiFigure 3: Dan Shui Station in Taipei

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enacted, such as presenting alternative mobil-ity options, offering programs to achieve higher per vehicle occupancy, providing incentives to reduce travel or push trips to off-peak hours, or convincing people to accomplish trip purposes through non-transportation means, such as telecommunications. A Maryland-based study shows that congestion pricing accomplished 80,000 changes in vehicle trips, while the sec-ond greatest catalyst proved to be van pooling, which produced only 15,000 changes.

Density and vehicle use

Less dense development cover more geo-graphical area, thus prompting vehicle use. Historical evidence of this can be found in ex-amining traditional walking cities from the year 1800 or earlier, whose density ranged from approximately 40-80 people per acre. Instead of separate commercial and residential zones, the cities, measuring about 3 miles across, were largely mixed-use. A transit-based city from 1920 or earlier makes an interesting comparison. Rail lines made density of 20-40 people per acre work, while communities ex-panded into nodes of “pedestrian pockets” that occupied a linear region . Today, we have car-dependent cities, which have been dominant on the landscape since the 1920s. These are characterized by a population density of 4-8 people per acre, and a typical urban radius of about 30 miles, which is segregated in zoning or usage. In a study of annual transit trips per capita, density proves successful as the city of Barcelona scores 230, with a population of 2.8 million people over 162 square kilome-ters. Densification is a widely recommended, planning/design-based strategy to achieve sustainable transportation objectives. Known scholars have recommended a range of density levels for transit and walkability and for place making. For example, Kevin Lynch and Allen Jacobs suggest a density of 12-20 units per acre, whereas Jane Jacobs supports 100 units per acre.

Sustainable solutions and transit oriented development

Steps that can be taken to better design for sustainable transportation include engineering design for traffic calming, and transit-oriented development. Engineering design is defined by the ITE Subcommittee on Traffic Calming as “the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users.” Other measures include speed and volume control. Vertical deflections such as speed humps and raised crosswalks are effective when dimensions are approximately 12-14 feet long, and 300-600 feet apart. Horizontal shifts include traffic circles and chicanes, or temporary bends in the road, to slow and con-trol traffic flow. Chokers, or narrowing of lanes, and center islands can be implemented as well. Partial or full closure of roads is another option. Problems associated with traffic calm-ing include delayed emergency responses, the potential for increased pollution due to frequent braking and accelerating, injuries to drivers with back or other physical problems, and traffic spillover.

Characteristics of transit-oriented develop-ment include transit access at the center of the system, location of development within ¼ to ½ mile radii from transit stops, moderate to high residential density, and mixed use of building types, with retail, services, and a variety of housing. Also particular to this scheme is pe-destrian-friendly design. Interconnected transit nodes organized along linear corridors develop in accordance with the speed of the chosen mode of transport. One of the most effective ways to encourage use of public transit is to design transit-oriented developments located close to public transportation. The combina-tion of housing, retail, and immediate access to mass transit allows residents to leave their individual automobiles at home as they walk to

FIgure 5: Public Transportation in Curitiba, Brazil FIgure 6: Buses in Curitiba, Brazil FIgure 7: A bus stop in Curtiba, Brazil

FIgure 8: Section showing transportation and density solutions in Curtiba, Brazil

FIgure 10: Public Transportation Center in Denver, CO

FIgure 9: Separating pedestrian and vehicular traffic in Denver, CO

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nearby stores and commute to work via bus, train, commuter rail, or light rail. The trinary system of integrated transit-land development in Curitiba, Brazil (Figure 8) shows a section view of this organizational structure.

Mixed-use should allowed and encouraged vertically, with living space allocated to the top floors and office and retail occupying the lower levels. Other configurations are possible as well, in which pedestrians and cars can occupy various street zones. In terms of hierarchy of modes of transportation, walking is given the highest priority, followed by transit, bicycle, and then autos. Designing with these priorities in mind “softens” the traditionally undesirable densities of city spaces. Squares and car-free parks are made possible, increasing the livabil-ity and aesthetic value of those spaces. Tacoma has implemented a similarly suc-cessful system by integrating the Link Light Rail spur with the interstate highway, park-and-rides, bus transit facilities, bicycle and pedestrian access, and commuter rail. Initial ridership goals were exceeded in the first week of operation, and ridership continues to increase. The electric powered trains are free of charge, run every ten minutes, and produce no street-level fumes, addressing another key concern--pollution--in a highly environmentally sensitive region. The DART system in Dal-las is another example of the permeation of TOD. A star TOD project can be found in the Mockingbird Station area in Dallas, TX. The project includes a 10-acre mixed use program with parking both underground and on grade. In addition, it provides 150,000 square feet of office space, 211 loft units, an 8-screen film theater, and 183,000 square feet of retail. This plan is part of a larger scheme that includes nodes running generally from north to south. Washington, D.C. is a best-practice example of transit-oriented development corridor, with several transit nodes built along a linear datum. Transit Oriented Development (TOD) can reconnect America. Potential TOD sites

throughout the United States include 3353 existing stations in 27 metropolitan areas. Some 700 additional transit stations have been planned for construction in the near future.

Models for Transit Oriented Development are economically as well as environmentally sus-tainable, to varying degrees. In London, 90% of the costs of the transit system are covered by rail fares. In Hong Kong, the transit system has become an economic center as well as a transportation hub. The LTR system was grant-ed land development rights by the govern-ment, and developed a comprehensive plan. They paid land costs under the “No Railway” basis. Property values increased, and MTR benefited from the value enhancement, which was then used to build new railways. At Tsing Yi station, a high-quality living environment was combined with retail and the rail station, as well as civic functions that would appear in a town hall. The government recovered 103.1 billion HK dollars from this mixed-use transit hub. Internationally, applications of the TOD model have proved successful in a range of cultural and economic contexts.

Case studies

Portland

An example of sustainable transportation in the domestic scene can be found in Portland, Oregon, where transit-oriented development has helped the city to bring new jobs and investments to the urban core, while enhanc-ing the city‘s transportation network and improving the inhabitants’ quality of life. The Portland Streetcar, which opened in 2001, has generated over $1.4 billion in development along its 4.7-mile loop.7 The city‘s Brewery Blocks is a mixed-use development which con-nects the Pearl District to the central business district. The project has caused property taxes to increase by over $1.3 million, and the land value has skyrocketed by 488%. Additionally, the project employs sustainable design for all

its buildings, a further emblem of Portland‘s dedication to smart growth.

Silver Spring

Silver Spring, an historic suburb of Washing-ton, D.C., has implemented transit-oriented development to revitalize its formerly dwindling downtown. It is connected to the main transit system of the D.C. subway, the Metro, which has resulted in a burst of economic growth for Silver Spring, linking residential areas within a large, walkable mixed-use center that includes the transportation hub. The development surprised city officials with its success, and at-tracted a large company to the area, Discovery Communications, which brought 1,554 new jobs to downtown Silver Spring. Business incentives with underlying New Urbanist prin-ciples of walkability, connectivity, and a safe, active streetscape, coupled with the power of economic investments, sponsorship, and marketing brought commercial entities to the center. The effects of this included a property tax revenue of $3.6 million, generated by the project between 200 and 2004, which equates to a 30% increase. Renovations of existing buildings totaled 1,052,580 square feet.

Conclusion

Sustainable transportation exists in a balance of economic forces, social and cultural condi-tion. It addresses issues of car dependency, use of energy and material resources, envi-ronmental impacts, and economy, promoting a cleaner, greener, peripatetic perspective. Achieving sustainable transportation hinges on a sustainable urban form, thus physical plan-ning and design play a critical role. Architectur-al visionaries such as Le Corbusier and Frank Lloyd Wright never restricted themselves to buildings only; they had ambitious regional thinking. Peter Calthorpe’s TOD applies to metropolitan area as well. A sustainable trans-portation system links individual localities to support a sustainable region.

FIgure 11: Public transportation in Houston, TX FIgure 13: Silver Spring, MDFIgure 12: Mass Transit in Hong Kong

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Glossary

Btu: British thermal unit. One Btu is the amount of heat required to raise the temperature of one pound of liquid water by one degree at a constant pressure of one atmosphere. Typi-cally it is used to talk about energy used to accomplish a task.

Congestion index: A ratio that expresses a direct comparison of miles traveled with the miles of road available to travel on.

GHG: An abbreviation for GreenHouse Gases, which comprise varying concentrations of water vapor, carbon dioxide, methane, ozone, and other wavelength-specific gases.

Sustainable transportation / sustainable mobil-ity / green transportation: transportation that does not endanger public health or ecosys-tems and meets mobility needs consistent with (a) use of renewable resources at or below their rates of regeneration and (b) use of non-renewable resources at or below the rates of development of renewable substitutes.

Notes

1. Rogers, Robin. “Green Transit.” Urban Land 65.6 (2006): 84-88.

2. Nyren, Ron. “Making Transportation Sus-tainable.” Urban Land 67.3 (2008): 36+38-39.

3. Hinchberger, Bill. “Jaime Lerner.” Metropolis 25.5 (2006): 77+110.

4. Quinn, Brian. “Transit-oriented Develop-ment: Lessons from California.” Built Environ-ment 32.3 (2006): 311-22.

5. Loukopoulos, Peter and Sholz, Roland W. “Sustainable Future Urban Mobility: Using Area Development Negotiations for Scenario Assessment and Participatory Strategic Plan-ning.” Environment and Planning A 36.12 (2004): 2203-2226.

6. Dunphy, Robert T. Developing Around Transit: Strategies and Solutions that Work. Washington, D.C.: Urban Land Institute, 2004.

7. Economic Development Council. “Economic Development and Smart Growth: Case Studies on the Connections between Smart Growth Development and Jobs, Wealth, and Quality of Life in Communities.”

8. University of Texas at Austin School of Architecture website. http://soa.utexas.edu/

people/profile/zhang/ming

Figures

All figures courtesy of Dr. Ming Zhang

Biography

Dr. Zhang is Associate Professor in the Com-munity and Regional Planning Program in the School of Architecture, University of Texas at Austin. Prior to joining UT Austin, Dr. Zhang held several academic and professional positions, including tenure-track Assistant Professor in the Department of Landscape Architecture & Urban Planning at Texas A&M University, Research Scientist at the Rock-efeller Institute of Government in Albany, New York, and Lecturer and licensed Planner/Archi-tect at the Huazhong (Central China) Univer-sity of Science & Technology, Wuhan, China.

Dr. Zhang’s research and teaching interests include urban transportation planning, trans-portation impacts on land use, urban form and travel behavior, GIS applications in urban and transportation planning, and land use/trans-portation issues in developing countries. His recent research has focused on the influence of the built environment on travel mode choice for work and non-work purposes, and transit-oriented development. Dr. Zhang has pub-lished (in both English and Chinese) over 40 journal articles and book chapters. His recent publications include “Travel choice with no alternatives: Can land use reduce automobile dependence?” in Journal of Planning Educa-tion and Research (2006) and “Bus Versus Rail: Meta-Analysis of Cost Characteristics, Carrying Capacities, and Land Use Impacts” in Transportation Research Record: Journal of the Transportation Research Board of the National Academies (2009).8