21st Century Urban Mobility

In order to decarbonize the urban environment, we must change not only how we get around cities, but also how cities themselves are planned.


By Christian Roselund
November 2019

California has been a poster child for the energy transition. The state was getting 29 percent of its electricity from renewable sources – not including large hydro dams – in 2017, with solar serving as the largest source. This has been a driving force in the state surpassing its 2020 goals for greenhouse gas reductions, well ahead of schedule.

The Golden State’s transition is not limited to its electric grid, and the cars on California’s roads and freeways are also changing. The state is home to nearly half the hybrid and electric vehicles in the United States, which make up 5 percent of its registered automobiles.

But despite all of this, California is not on track to reach either its 2030 target to reduce greenhouse gas emissions 40 percent from 1990 levels, or its 2050 targets, as documented in reports by the California Air Resources Board (CARB) and nonprofit Next10. The state is also experiencing extremely high housing costs, with single-family home prices in the San Francisco Bay Area rising 6 percent each year for the past decade. California Governor Gavin Newsom has identified this as a crisis, noting that high housing costs are exacerbating economic inequality.

Ultimately, a root cause of both the failure to meet climate targets and high housing costs can be traced to California’s 12-lane freeways and sprawling suburbs of single-family homes. More than 40 percent of California’s emissions are transportation-related, with passenger vehicles being the biggest contributor to this, at 28 percent of all emissions on their own. Meanwhile, a lack of locations to build more dense housing is driving up prices and pushing commuters farther from their jobs.

California has more than 80 cars for every hundred residents, and even with the increasing share of electric vehicles, the number of internal combustion engine (ICE) cars per 100 residents has been increasing since 2012. Like elsewhere in the United States, these cars spend a lot of time sitting idle in parking lots and garages.

The state is beginning to understand this problem. In its 2017 scoping plan, CARB made it clear that even with accelerated adoption of EVs, “vehicle miles traveled reductions are necessary to achieve the 2030 target and must be part of any strategy evaluated in this plan.”

Redesigning Cities

California shares these problems with many other states that will face the same struggle when they finally get around to setting ambitious targets and doing in-depth research on sources of emissions. Nor is this issue limited to the United States. Across the world, more and more people are moving to cities, which are where most of our energy consumption happens, and more and more of them are buying cars.

The increasing move of the world's population from rural to urban areas makes the issue of addressing urban transportation and land use emissions all the more urgent.

And while many are pinning their hopes on vehicle electrification, the strategy to reduce emissions by moving from ICE vehicles to EVs faces one central challenge: vehicle lifetimes. Ben Holland, a senior associate in Rocky Mountain Institute’s mobility team, estimates that the average car in the United States stays on the road for 11 years. That means that even if we shift more rapidly to EVs, we are going to be stuck with the emissions of any ICE cars that are still on the market for 11 years after they leave the lot.

But where there is challenge, there is also opportunity; in this case the opportunity to redesign cities for people, including greater density, more accessible services, and more efficient, safe, and equitable transportation, including through better mobility services.

Many Approaches

The concept of designing communities for diverse uses and mobility beyond personal automobiles is far from new; the New Urbanist movement has been championing these principles for decades. “New Urbanism has always represented the building blocks of sustainable design,” notes Evan Costagliola, the co-lead of the emerging mobility practice at pioneering transportation firm Nelson Nygaard.

Costagliola says that his firm focuses on “people-oriented transportation systems,” as a layer on top of the New Urbanist movement. And he notes that cities are deploying a wide variety of means to shift their transportation systems, with congestion pricing as a popular route. “In just one year, London’s congestion pricing program reduced the amount of cars on the road by 15 percent and cut congestion by 30 percent,” states RMI’s Ben Holland.

“New Urbanism has always represented the building blocks of sustainable design.”

“There are a lot of cities that actively engaged in studies or implementation that is related to congestion pricing,” notes Costagliola. But beyond this, there is a need for infrastructure such as bike lanes and paths, expanded mass transit systems, and more opportunities for people to walk. “I would lead first with transit, safe infrastructure, and design,” explains Costagliola.

But Nelson Nygaard’s approach is not the only one to confront the challenges of mobility. In its work RMI has emphasized a systems approach to transforming urban mobility, one that embraces new technologies and seeks to harness them.

The mobile phone revolution has led to an explosion of shared and on-demand services, from rideshares to scooter rentals, and the entirely new field of “mobility as a service.” In many places, existing mass transit has yet to catch up, and in some places the climate benefits of technological innovations such as ridesharing are unclear at best if not reversed by services such as Uber and Lyft.

But despite unintended consequences, these new services are wildly popular and not going away. RMI emphasizes planning and integration in order to harness potential gains and improve outcomes, and to move cities to shared, connected, and clean services.

Land Use

It is not only the mobility systems that need to change in order to reduce the carbon footprint of cities; it is also the pattern of building. One perspective shared by the New Urbanist movement and RMI is to emphasize a move to greater density and away from isolated residential-only development to mixed-use neighborhoods and clusters.

And this can be as simple as allowing neighborhoods to accommodate grocery stores and other key destinations. RMI’s Holland estimates that commuting to and from work represents only 30 percent of the vehicle miles traveled in the United States. “You have this massive chunk of driving that has nothing to do with going to work—it is everything else,” he notes. “Allowing certain communities to have access to things like corner stores would actually reduce vehicle miles traveled.”

New York City - overhead view of a corner market at night in the Chinatown neighborhood on Manhattan in NYC. Credit

Holland describes “antiquated” land development restrictions as a barrier. This includes single-family zoning, which is being challenged in forward-thinking cities such as Minneapolis. “Single-family zoning is a ban on all the things that we need,” states Holland.

Allowing for greater density not only has climate benefits but can also increase the number of units available to renters and home buyers. This in turn can take pressure off of costs and allow more residents to live closer to services and their workplaces.

As usual, systems thinking can yield even greater benefits. In the 2011 report Our Cities Ourselves, the Institute for Transportation and Development Policy articulates a strategy of allowing for increased density around transportation nodes, which it says can “maintain the viability of transit in the long run, shorten trip distances, save travel time, and preserve millions of square kilometers of arable land.” Such ideas are already being put into practice around the world, with the cities of Curitaba, Brazil, and Guangzhou, China, increasing density along bus rapid transit (BRT) routes.

New Cities, New Paradigms, New Opportunities

The implementation of these ideas in the United States and other developed nations is necessary, but it is also a slow process of changing codes and rebuilding infrastructure. And this is particularly challenging in “sunbelt” cities in the United States that were rapidly expanded after World War II.

“There is a history of massive investments in car infrastructure that cities are rebounding from,” notes Costagliola. “Because the infrastructure is primarily enabling a car-oriented lifestyle, it will continue to be very difficult to shift people away from their cars.”

The developing world presents a very different set of conditions. According to a study by McKinsey, 70 percent of India’s 2030 infrastructure has yet to be built. And while California has 80 cars per 100 residents, in India it is closer to 1.8 cars per 100 people.

Ryan Laemel, a manager in Rocky Mountain Institute’s India program, describes a “western paradigm of mobility that is dominated by private ownership and underutilized assets.” And while he warns that this paradigm has the potential to be the future for India and elsewhere, this is not a given. “Given India’s low rate of private vehicle ownership, we see an opportunity to leapfrog to a new mobility paradigm.”


In the Indian city of Pune, where RMI is engaged in mobility work, 50 percent of people get around by walking or bicycling, with nearly 30 percent using two-wheeled motorized vehicles. Buses make up more than 10 percent of trips, leaving the share of private vehicles at just over 5 percent. An increasing number of the two- and four-wheeled vehicles on the road are for hire, including everything from rickshaw taxis to digital-ride hailing platforms like Uber or Ola.

“Given India’s low rate of private vehicle ownership, we see an opportunity to leapfrog to the new mobility paradigm without going through the paradigm of the Western world.”

Laemel notes that mobility services have the potential to challenge the traditional status symbol of car ownership that has dominated the West for many decades. “Younger generations are starting to see it less as a status symbol,” he says. “It is going to have to be a true cultural shift.”

But this does not mean that Laemel accepts that cities must be designed either for cars or for people. “There is a need to reconcile that they both have their own place,” he argues.

Money, Data, and Integration

RMI’s partner in Pune, the Pune Municipal Corporation, has focused part of its mobility work on helping the city reclaim space for non-motorized forms of transit like walking and cycling. This included consulting on a project to transform a street in Pune into a leading example of safe, well designed non-motorized transport infrastructure.

However, these types of infrastructure retrofit projects can be expensive. A big challenge for implementing these systems is paying for the up-front costs, which can be even more of a barrier in the developing world. “Getting cities the patient, risk-tolerant capital that they need is tough,” notes Laemel.

A redesigned street in Pune, India. Credit: Ryan Laemel, RMI

This is tied to the challenge of information and being able to estimate how much transitions will cost versus how much they will save. And there are other essential applications for data, such as to allow for integration of mobility services. “Data, in my opinion, is going to be this really powerful connective tissue,” Laemel states. “It is going to allow you and me to have full transparency into all of the different mobility options.”

“Data is going to be this really powerful connective tissue.”

And this is not work that RMI or any actor can do on its own. Laemel emphasizes that the integration of urban systems will require a “super-collaborative approach” to achieve the best results. He warns that a lack of integration can endanger any project. “If you are thinking about a BRT system or metro but not thinking about last-mile connectivity to that line, and what streets will have to be torn up, you are going to run into trouble,” explains Laemel.

With so many different forms of transit and options to redesign cities, this can be bewildering. But Laemel says the important thing is to start small. “There are small changes that cities can make,” he says. “The first thing is a need to identify a champion that is going to really believe in this work. You need to make the value proposition around why changes in the built environment can help to drive prosperity.”

Ultimately, the challenge of creating low-carbon urban systems for the 21st century is a huge task, and it can take an integrative and holistic approach to bring all of this together. “It is about integrating these seemingly disparate parts,” states Laemel. “You can have all of the ingredients, but it takes a recipe to make a meal.”