Transportation contributes the largest, and a still growing, share of energy-related carbon emissions worldwide. Urban mobility is a major contributor, as the use of high-emitting motor vehicles is escalating globally. ITDP works in key cities around the world to promote zero-emission, sustainable, and inclusive urban mobility. ITDP uses four interlocking strategies to accomplish the greatest possible impact: advancing inclusive, compact cities; increasing accessible, low- to no-emission mobility; promoting transport electrification; and controlling polluting, private vehicles. These four strategies are each powerful, but combining them achieves an impact greater than the sum of its parts.
Once they’re built, cities change slowly. Indeed, the street grids of central Rome and Istanbul have remained remarkably similar for 1,000 years. After a city has built highways, parking garages, and low-density suburbs, it is difficult to convert those areas to support sustainable mobility. Even with a shift to electric cars, these cities and surrounding regions will continue to spew carbon for decades. Carbon emissions are only part of the problem. Automobile dependence has increased traffic injuries and deaths, reduced access to jobs and services, and raised transportation costs. These negative impacts fall disproportionately on the most vulnerable members of society.
Yet cities in low- and middle-income countries can choose a different path. UN-DESA projects that by 2050 an additional 2.5 billion people will move to cities—close to 90% of them in Asia and Africa. As cities grow, they have an opportunity to invest in sustainable urban mobility, reducing global greenhouse gas emissions by tens of millions of tonnes, before locking in a car-centered, high-carbon future.
The integration of compact, mixed-use urban development with public transit lays the foundation for massive reductions in CO2 emissions. In the U.S., residents of car-oriented suburbs have a total carbon footprint two to three times higher than those in walkable, transit-friendly cities.
Sprawl leads to more driving, and with more cars on the road, GHG emissions skyrocket.
Cities like Paris, Singapore, and Vancouver have embraced the principle of the 15-minute neighborhood, ensuring that all residents can meet their daily needs within a 15-minute walk. These cities are building compact housing, mixing commercial and residential zoning, setting up a tight network of walkable streets, and anchoring neighborhoods around rapid transit stations. In 15-minute neighborhoods, people not only live, but thrive, without cars.
Carbon reduction isn’t the only benefit of density. Sprawling cities have to pay more money per resident to pave roads, lay sewers, and provide services. They also have to bulldoze more natural land or farmland to build housing. Sustainable land use policy—that which prioritizes density, mixed uses, and proximity to transit—creates potential for a greener future. This is most crucial for the many rapidly growing cities in economically developing countries.
This map of per capita carbon emissions in the northeastern U.S. shows how residents of sprawling suburbs emit many times more CO2 per household than residents of compact cities. Measured in tonnes of CO2 equivalent, broken down geographically by zip code and metropolitan region. Research by UC Berkeley researchers.
First, a city must make it convenient, safe, and cost-effective for people to get around using sustainable transportation. The three pillars of sustainable urban mobility are walking, cycling, and public transit—in that order. Walking is the most sustainable, healthful, economical, and equitable way for people to move around cities for short trips; but some people will need to travel farther than they can get on foot. A network of safe, physically protected bicycle lanes and public transit that arrives every 10 minutes or less ensures that people will not default to driving.
According to ITDP’s Pedestrians First walkability tool, Bogotá, Colombia, has one of the highest rates of people living near frequent public transit in the world: 88%. When people can access transit by walking, they are able to both walk and ride transit more easily.
Every part of a city’s mobility system can be improved by replacing fossil fuel power with electricity. Electrification is an important enhancement to sustainable mobility, but it’s not the only solution. The transition from internal-combustion motorcycles, cars, and buses to electric vehicles must be coupled with a shift from private cars to walking, cycling, and transit. Electric bicycles are especially important because they help people travel without cars for journeys that might be difficult on foot.
Together, vehicle electrification and non-car-based transport will have a greater impact than either could alone. To reach its full impact, electrification must also be combined with efforts to replace polluting power plants with sustainable alternatives.
In cities where it is practical and pleasant to get around by walking, cycling, and riding transit, decision-makers must also consider measures to reduce the incentives that promote car travel. These often-hidden incentives include underpriced parking and new or overly wide roadways.
Cities should stop building new highways, providing low-cost parking, and enforcing parking minimums for new buildings. Planners can prioritize people, instead of vehicles, by narrowing roadways and creating places for walking and cycling. By removing free parking, establishing parking maximums, and implementing pricing strategies, cities can reduce demand for driving and generate revenue for sustainable mobility. Then, cities can institute more difficult traffic control policies like congestion pricing or zero-emission areas. Together, these measures can massively reduce greenhouse gas emissions, while raising revenue that can be used for more sidewalks, better bike paths, and improved public transport.