Transportation and Sustainability

Module Introduction

By Olivia Edwards

“Beyond a certain speed, motorized vehicles create remoteness which they alone can shrink. They create distances for all and shrink them for only a few. A new dirt road through the wilderness brings the city within view, but not within reach, of most Brazilian subsistence farmers. The new expressway expands Chicago, but it sucks those who are well-wheeled away from a downtown that decays into a ghetto.”

― Ivan Illich, Energy and Equity

A Challenge to Sustainability

For many centuries, before the development of motorized vehicles, humans traversed the globe in a variety of ingenious transportation methods, from animal use to small boats to human labor. The advent of engines and the use of fossil fuels at the start of the industrial revolution, transformed transportation and enabled impressive worldwide technological and social achievements in the modern world.

However, in the 21st century, transportation, particularly via vehicles powered with fossil fuels, is a major contributor to environmental degradation, ill health, reduced quality of life, and increased economic inequalities. The challenge posed by motorized vehicles is growing across the globe. A UN-Habitat report illustrates this upward trend in motorization, projecting the number of motor vehicles worldwide to grow to 1.6 billion by 2035 and to double to 2.1 billion by 2050, up from 1 billion in 2010. Moreover, passenger traffic is estimated to increase by 50 percent to exceed 80,000 billion passenger-kilometers, while global freight volume will grow 70 percent by 2030. Unsurprisingly, increased C02 emissions have accompanied this growth – transportation is responsible for the most CO2 emissions of the four end-use sectors since the late 1990s – accounting for 23 percent of total energy-related CO2 emissions in 2010. Greenhouse gas emissions from the transport sector have increased at a faster rate than any other energy end-use, more than doubling since 1970.

The adverse effects of harmful gas emissions are well-documented, ranging from the depletion of the ozone layer and resulting global warming to acid rain that damages crops, vegetation, and infrastructure. Particulate matter, carbon monoxide, and other car pollutants cause health conditions like skin and eye irritation, allergies, and respiratory problems. Outdoor air pollution generally was estimated to cause 3.7 million premature deaths globally in 2012. Eighty-eight percent of these deaths occurred in low and middle-income countries, a statistic which highlights the reality of adverse health outcomes created by wealth gaps and transportation inequalities. The economic effects of time and fuel wastage are quantifiable as well, with time lost in traffic amounting to 0.7 percent of Gross Domestic product (GDP) in the US, 1.2 percent in the UK, 5.3 percent in Beijing, China, and as much as 10 percent in Lima, Peru, where people spend an average of four hours in traffic a day.

Shifting Gears

That a new approach to transportation – one that favors sustainability, mobility, and equity – is needed is evident. An equally apparent but opposing parallel is how reliant the world is on the automobile for trade and private and commercial transport. With so many people depending on the automobile as their primary or sole means of transportation, implementing structural and technological changes in the way we travel will only remedy part of the problem. Educating people about alternative modes of transportation and developing new travel habits and preferences will go a long way towards resolving the challenge. To understand how we might begin to escape this dependency, it is useful to examine how we got to this point.

In the developed world, the proliferation of personal vehicles and the road infrastructure required to support them can be traced back to the “predict and provide” approach to traffic management that was first introduced in the U.S. in the 1950s and 60s. This market-led approach looks at past trends and travel habits to generate future traffic predictions. Road space is increased in anticipation of projected traffic growth in a self-fulfilling cycle that generates more congestion as the expanded supply of infrastructure increases road usage and in turn generates ever-more demand. Closely intertwined with the evolution of predict and provide is the concurrent growth of the auto industry as population growth has expanded to the suburbs and households began looking to the automobile as an essential component of the middle-class lifestyles.

Planning for a Sustainable Future

When transportation czars and city planners discuss the future of sustainable transportation, they are laying the blueprints for systems that will enable not just greater movement, but enhanced mobility. Mobility goes beyond the material transport of people and goods to include the concept of access – access to transportation options that are safe, convenient, reliable, and affordable.

The accessibility of a given mode of transportation can be measured by the time and costs associated with using that mode to travel along a route from one point to another. Time considerations include the actual travel time of the route and of getting to and from the station entry and exit points, as well as the time spent waiting during regularly scheduled service and delays. Inter-related factors include proximity to station locations and the convenience/frequency of routes and schedules. Costs encompass the direct cost of the fare in addition to any expenses incurred in utilizing the transit, such as fuel to and from the station and parking fees. Accessible transportation reduces both factors so that when travel times and costs are low – that is, transportation is convenient and affordable – access is improved and mobility is greater. This concept is key to creating sustainable transportation systems that can meet the demand of future generations in a more congested, connected, and environmentally vulnerable world.

The World Bank has developed a framework centered around these intertwined concepts of mobility and access, defining sustainable mobility as the realization of four global goals: (1) equitable access; (2) security and safety; (3) efficiency; and (4) pollution and climate-responsiveness. This vision includes better provision of transportation infrastructure and services and holds that all these elements work together in the service of the movement of people and goods.

With so much of human life centered around the automobile and the convenience it provides, a radical shift in thinking about and planning for transportation is needed to move the world into a new sustainable, mobile age that is no longer wedded to the road. One such approach gaining prominence is Transport Demand Management (TDM), which flips the traditional predict and provide model by matching the demand for travel to the supply of infrastructure, as opposed to endlessly expanding supply to meet demand. TDM encompasses strategies that seek to increase overall system efficiency by promoting a shift from carbon-intensive single-occupancy vehicles (SOV) to more energy efficient non-SOV modes and by reducing auto trips more widely.

Such alternatives include electric vehicles, ridesharing services, carpool and van, public transportation systems like bus, heavy/light rail, and commuter rail, as well as the non-motorized modes of walking, cycling, and telecommuting. Aside from easing traffic congestion, public transit systems, particularly those that make use of clean alternative fuels and technologies, have a real and measurable impact on environmental quality. The U.S. Department of Transportation found that national averages for greenhouse gas emissions are much lower for all forms of public transit compared to private vehicles. Heavy rail transit like subways and metro systems produce 76% lower greenhouse gas emissions than an average SOV per passenger mile. Meanwhile light rail transit (LRT) systems generate an average of 62% less emissions and bus transit produce 33% less per passenger mile.

Along with the overarching mandate to reduce trips taken by auto, TDM endeavors to transform the transportation paradigm more broadly by employing various techniques to put people at the center of travel. One of these strategies, the Avoid-Shift-Improve (ASI) framework, tackles the concurrent goals of lowering emissions and congestion to make cities more livable while reducing the need for travel overall. In this model, the “Avoid” component incorporates improved land use planning and travel demand management to reduce the demand for travel and trip lengths. “Shift” entails pivoting to more sustainable means of transportation, such as non-motorized transport and public transit. “Improve” seeks to enhance fuel efficiency and develop low-emission vehicle and infrastructure technology.

Incentives are a key component of this strategy, from infrastructure – protected bike lanes, dedicated bus lines or bus rapid transit (BRT), and high-occupancy vehicle (HOV) lanes – to monetary – congestion pricing, employee transit benefits and subsidies, and reducing parking minimums for new developments. In this model, shifting priority away from the automobile as the primary mode of transportation is not limited to investing in and promoting alternative modes. The approach considers not only the physical procurement of these systems, but also concerns around safety, quality, and service-levels. This might include features such as a simplified fare structure and payment system or the availability of accurate, real-time arrival information.

To achieve this transformation, public transportation systems are incorporating Intelligent Transport Systems (ITS) technologies to enable more efficient and effective transport and better traffic management through the real-time flow of information and data. ERTICO, a leading proponent of ITS across Europe, envisions the future of intelligent mobility as safer (zero accidents), smarter (no delays and fully-informed users), and cleaner (reduced impact on the environment). Services are seamless and affordable to use while providing security and respecting the individual’s need for space and privacy.

To be effective, TDM and ASI strategies should be used in conjunction with transit-oriented development (TOD), an urban or community development model that encourages compact, mixed-use development within walking distance of quality public transportation. TOD seeks to create more walkable, livable cities while expanding mobility choices and reducing traffic congestion. Greater density and improved mobility provide people, particularly the poor and underserved, better access to jobs, educational and health services, and opportunities for social interactions. Benefits extend beyond the social and economic to ecological improvements. A 2019 report by the Transit Cooperative Research Program (TCRP) found that TOD can decrease the amount of farmland and environmentally sensitive areas converted into housing and commercial development by encouraging in-fill and small lot projects. This reduces fragmentation of the natural habitat, thereby preserving biodiversity and improving water quality by reducing runoff.

The Promise of Sustainable Transportation

Ultimately, all these planning strategies and techniques work together towards generating an understanding of transportation that places sustainable mobility and accessibility at its heart. Transportation is not simply movement for movement’s sake. When done well, it is a tool that empowers people to make choices about how, when, and where they will travel, and it does so in a way that improves the lives of its users while limiting or eliminating adverse environmental outcomes. For evidence of this, we need look no further than a recent Mercer Quality of Life ranking for 2019, which found that not a single highly automobile-dependent city ranked well, while all those cities rated as most livable boast good to excellent public transport systems. Meanwhile, Atlanta, the American city with the unenviable superlatives of highest car-usage and most sprawling major city, was ranked as the least livable of all U.S. cities in terms of transportation. To foster the kind of vibrant, connected places where people want to live while ensuring that we act as good stewards of the planet, the tenets of sustainable mobility must be at the core of all levels of planning, regional and national to local and household alike.


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