Emissions from transportation are the fastest growing source of global greenhouse gas emissions, with emissions expected to increase 300 percent by 2050, according to research by the Worldwatch Institute. Today, emissions from transportation contribute to approximately 80 percent of the harmful air pollutants that result in 1.3 million premature deaths annually, according to Michael Replogle and Colin Hughes of the Institute for Transportation and Development Policy (ITDP).

The two authored the fourth chapter, "Moving Toward Sustainable Transport, in Worldwatch's book State of the World 2012: Moving Toward Sustainable Prosperity, published in April.

The largest financial commitment made at the Rio+20 Conference on Sustainable Development in June 2012 was a pledge by the 8 largest multilateral development banks (MDBs) to commit 500 staff and to dedicate $175 billion for more sustainable transportation in the coming decade. This unprecedented agreement was facilitated by the Partnership on Sustainable Low Carbon Transport (SLoCaT), which brings together 68 MDBs, civil society organizations, UN agencies, and research and industry organizations.

"This action promises to begin countering decades of unsustainable investments in transportation systems, such as building high-capacity motorways," said Michael Renner, Worldwatch Senior Researcher and State of the World 2012 project co-director. "But it will require new resources for civil society groups to be able to ensure independent monitoring of impacts and follow-through by MDBs."

"If transportation investments and management policies foster walking, cycling, use of high quality public transportation, and smart traffic management, growing urbanization can reduce consumption of scarce resources, protect public health, and deliver happier, nicer cities," said Michael Replogle, Managing Director for Policy and Founder of ITDP and State of the World 2012 contributing author.

"These unprecedented MDB financial and reporting commitments present an opportunity to leverage large shifts in domestic and private transportation investment and to build capacity for a paradigm shift."

The demands on transportation infrastructure continue to mount. Without changes in policy, 2 to 3 billion cars will be on the world's roads by 2050, in comparison to 800 million cars today, according to the International Energy Agency.

Current transportation and land development patterns disadvantage the poor, often forcing them to choose between low incomes in informal-sector employment that is close to affordable housing, or somewhat higher-paying jobs that are reachable only if they spend a large share of their income and hours each day commuting. In many cities, the urban poor cannot afford public transportation and end up walking long distances.

Additionally, in many places it is unsafe to walk. In Surabaya, Indonesia, for example, 60 percent of roads have no usable sidewalks.

"All of these negative consequences are not inevitable results of urbanization and development," said Colin Hughes, Global Policy Director at ITDP and State of the World 2012 contributing author.

"Experience in some cities show that in comparison to a business-as-usual rapid motorization strategy, sustainable transport strategies can address rising mobility needs that accompany increases in population, employment, and trade at a lower cost overall, with more job creation and fewer adverse impacts."

The key to this approach is a new sustainability paradigm called "Avoid, shift, and improve:"

+ Avoid unnecessary trips with smarter planning, pricing, and telecommunications;

+ Shift trips to more sustainable modes with investments in bus rapid transit (BRT), walking, cycling, and traffic management, by limiting and pricing parking, by applying polluter-pays incentives, and offering better traveler information; and

+ Improve vehicle efficiency with cleaner fuels, better-operated networks, and efficient vehicle technology adapted to local conditions and requirements.

+ In their State of the World chapter, Replogle and Hughes highlight three examples of this approach, revealing how it improves transport in urban areas:

Rapid bus transit in Bogota, Colombia: In 2000, Bogota opened TransMilenio, a BRT system with nine routes extending 54 miles (about 87 kilometers) throughout the city. By 2011, TransMilenio's ridership was up to 1.7 million passengers daily and the fare for a single trip was 1,600 Colombian pesos (about US$0.85).

Congestion and emission charging in London: Drivers who enter congested central London pay a "congestion charge." The drivers have the option to pay Pounds 10 (approximately US$15)in advance, or they must pay the charge within a certain time after driving through the congested streets, or be fined up to Pounds 120 (almost US$184).

The charge generates funds for public transportation, and bus use is up 6 percent during charging hours. A similar Low Emission Zone covers heavy goods vehicles across the whole city, charging more polluting trucks and buses Pounds 100-200 per day (approximately US$150-300) to drive in the area.

Public bicycles in Hangzhou, China: With a population of 6.7 million, Hangzhou is one of China's fastest-growing cities. This growth comes with rapid motorization. In 2008, Hangzhou launched a bike-share program that currently provides 60,000 bikes.

The program has alleviated pressure on roadways and is accessible to all because of its pricing scheme----the first hour of bike use is free and the second hour is approximately US$0.15. The city reports that 90 percent of total trips are made in that first free hour, and more than 25 percent of trips are made during peak commuting times.

Innovations like these can improve travel options for the urban poor while reducing harmful emissions caused by transportation.

"With additional international support and funding under the MDB commitment at Rio+20, developing countries will find it easier to shift their development of transportation from emphasizing rapid motorization and car-dependence to instead fostering public transport and lower emissions transportation options," Replogle said. "This moves us towards the kind of support we called for in our State of the World 2012 chapter."

Worldwatch's State of the World 2012, released in April 2012, focuses on the themes of inclusive sustainable development discussed at Rio+20, the 20-year follow-up to the historic 1992 Earth Summit, which was also held in Rio de Janeiro. The report presents a selection of innovations and constructive ideas for achieving environmental sustainability globally while meeting human needs and providing jobs and dignity for all.