CAMBRIDGE, Mass. -- People's insatiable appetite for mobility is heading the world's transportation systems toward unsustainable gridlock and environmental degradation unless several grand challenges are tackled, MIT researchers and colleagues conclude in an Oct. 13 report on worldwide mobility at the end of the 20th century.
The researchers warn, for example, that by 2015, greenhouse gas emissions from transport in the developing world will exceed those in the industrialized world unless we can improve the fuel economy of cars and trucks and curb traffic growth. Grand challenges to that end include reinventing public transport and creating a portfolio of mobility options for people and freight.
"Transportation is essential for moving people and goods, but it also has a broader role. It shapes our cities, stimulates economic growth and makes possible societal interactions. Unfortunately, it also has harmful side effects that must be looked at carefully and systematically," said Daniel Roos, associate dean for engineering systems, director of the Engineering Systems Division and one of three MIT project leaders.
"Mobility 2001" was conducted by MIT and Charles River Associates and is the first phase of a three-year study commissioned by the World Business Council for Sustainable Development (WBCSD). The goal of the overall initiative is to develop a global vision of sustainable mobility for 2030 and possible pathways to get there.
The six-month, million-dollar first-phase study was a joint effort of the Laboratory for Energy and the Environment, and the Engineering Systems Division. MIT researchers from 10 departments, laboratories and centers collaborated to assess the current state of mobility and its impacts in a holistic way. Those involved drew on expertise gained in other ongoing studies that consider mobility and global warming, transportation networks, transportation technology for 2020 and mobility demand forecasts for 2050.
Also critical was collaboration with the 11 WBCSD fuel and auto companies that sponsored the study. David H. Marks, professor and director of the Laboratory for Energy and the Environment, said, "We're fortunate to be collaborating with this group. If we're going to understand the major challenges and then plan and implement change, it's critical that auto manufacturers and energy companies together come up with ideas about how we can move toward sustainable mobility and present those ideas to stakeholders."
Said John B. Heywood, the Sun Jae Professor of Mechanical Engineering and director of the Sloan Automotive Laboratory, "Other studies of mobility tend to focus on only part of the problem-one country or one mode of transport, for example. We've attempted to make this study both broad and comprehensive."
The report considers both passenger and freight and all modes of transport (ground, air and ocean). It looks at mobility's impact on economic development, social welfare and environmental quality. And it considers both developed and developing countries, incorporating information gathered at "stakeholder" meetings with environmentalists, governments, researchers, students and consumer groups around the world.
TOO MANY CARS, TOO FEW ROADS
The assessment paints a sobering picture of trends in automobile travel. In the developed world, the auto is the main provider of mobility in virtually all urban areas. Urban sprawl is increasing as the affluent move to the suburbs, where low population densities make public transport difficult. New highways can't be built fast enough to keep up with the increasing traffic, largely due to concerns about associated environmental and social disruption. And there is a growing pool of older people who won't be served well by today's automobile-dependent system.
In the developing world, rapid population growth, urbanization and the startup of suburbanization are making conditions even worse. Increasing prosperity has led to a phenomenol increase in the number of private vehicles. (Historical data are consistent the world over: when incomes rise, people buy cars.) Rapidly growing megacities have little time or money to build public transport systems or to expand roads to handle the new traffic. The result is serious congestion, economic and environmental damage, and major safety problems. Energy use and associated emissions are skyrocketing, in part due to the use of older cars and dirtier fuels.
ENVIRONMENTAL AND FUEL CONCERNS
Analyses of the environmental impacts of our mobility systems generally focus on greenhouse gas emissions and climate change. But building and using roads, bridges, airports and harbors also degrade local and regional ecosystems, damage natural habitats and kill off species, leading to loss of biodiversity. These impacts may be more damaging in the long term than generally recognized.
The environmental impacts of airplanes in flight are also often underestimated. Air transport is responsible for 8-12 percent of transport-related carbon emissions. But because the carbon is emitted at high altitude, its potential impact on global warming is twice as great as that of carbon emitted at ground level. And air transport is growing, especially for intercity travel.
Freight transportation systems are also an unexpectedly large source of carbon emissions. Current freight transportation is relatively energy efficient, but it uses about 43 percent of all transportation energy. The need to transport goods over longer distances is increasing, and the ongoing competition for road space between freight and passenger traffic is a growing global problem. Transportation of goods over long distances is generally already carefully optimized, but the last few miles of delivery-for example, from supermarket to home-is not.
Another concern is that more than 96 percent of the world's transportation depends on petroleum, and with good reason. Petroleum yields high-energy-density fuels that will be hard to beat. Petroleum-burning vehicles are becoming more fuel efficient and cleaner, but thus far those improvements have been offset by factors such as growth in the vehicle fleet, increased driving, and use of larger and faster vehicles.
THE GRAND CHALLENGES
In summarizing their findings, the researchers identified the following set of "grand challenges" that, if successfully addressed, would dramatically improve the sustainability of mobility:
- Ensure that transport systems serve essential human needs, enhance the quality of life and support economic development.
- Adapt vehicles to evolving requirements on air pollutant emissions, vehicle load-carrying capacity, amount of fuel use and ownership structure.
- Reinvent public transport to provide mobility to those who don't have access to cars and a reasonable alternative for those who do.
- Reinvent the process of planning, developing and managing mobility infrastructure.
- Reduce carbon dioxide emissions.
- Resolve the competition for use of infrastructure between personal and freight transportation.
- Tackle congestion by developing a portfolio of mobility options for people and freight.
Technological change can play a major role in addressing most of these challenges. But there is one more overarching challenge: to create the institutional capability and political will needed to tackle such complex, long-term issues. Developing consensus and implementing plans will require a level of agreement and cooperation among citizens, governments and the private sector that's unprecedented in most parts of the world. Ultimately, the pace and direction of change in the world's mobility systems will hinge on institutional issues in the developed and developing world alike.
The Sustainable Mobility Project now moves into its next phase, which calls for devising strategies aimed at making mobility sustainable over the coming decades.
The "Mobility 2001" report can be downloaded from the Laboratory for Energy and the Environment's home page at http://lfee.mit.edu.
