The study considers two main future scenarios: a baseline urban scenario calibrated to the IEA 2012 Energy Technology Perspectives 4° Scenario and the authors’ “High Shift” (HS) scenario, which projects an aggressive shift in global transport investment to far greater urban passenger travel by clean public transport and non-motorized modes, along with a reduction in the rate of growth of private vehicles and the decrease in the rates of road construction, parking garages and other ways in which car ownership is encouraged.

The study found that the High Shift scenario could save more than $100 trillion in public and private capital and operating costs of urban transportation between now and 2050 compared to the baseline scenario.

Overall, the total costs of the baseline between 2010-2050 are roughly $500 trillion ($200T in OECD and $300T in non-OECD countries). The costs of the “High Shift” (HS) are about $400 trillion ($160T in OECD and $240T in non-OECD countries). The HS scenario would also eliminate about 1.7 gigatons of carbon dioxide annually—a 40% reduction of urban passenger transport emissions—by 2050.

Further, an estimated 1.4 million early deaths associated with exposure to vehicle tailpipe emissions could be avoided annually by 2050 if governments require the strongest vehicle pollution controls and ultralow-sulfur fuels, according to a related analysis by the International Council on Clean Transportation included in the report.

Doubling motor vehicle fuel economy requirements could also reduce CO₂ emissions by an additional 700 megatons in 2050.

The study shows that getting away from car-centric development, especially in rapidly developing economies, will cut urban CO₂ dramatically and also reduce costs. It is also critical to reduce the energy use and carbon emissions of all vehicles.

—Lew Fulton, co-director of NextSTEPS Program at the UC Davis Institute of Transportation Studies

Transportation, driven by rapid growth in car use, has been the fastest growing source of CO₂ in the world. An affordable but largely overlooked way to cut that pollution is to give people clean options to use public transportation, walking and cycling. This expands mobility options, especially for the poor, and curbs air pollution from traffic.

—Michael Replogle, managing director for policy at ITDP

Assumptions in the HS scenario include:

• Total urban passenger mobility through 2050 (measured as passenger-kilometers, pkm) is roughly preserved from the baseline scenario in the same year and region. In some areas, such as the US and Canada, lower levels of travel reflect improved urban planning and urban re-agglomeration that lowers trip lengths. Africa experiences a large increase in total mobility in High Shift because a similar increase in transit and NMT (non-motorized transport) as occurs in other regions along with a 50% reduction in LDV travel results in much higher total travel levels than in the baseline.

• HS assumes lower private ownership rates, along with lower travel per vehicle and somewhat higher occupancy rates. All of these would need to be achieved through policy and pricing initiatives, since autonomous changes in lifestyle that might affect car ownership are already included in the baseline.

• For public transportation modes, the average number and length of systems, as well as the modal capacity, frequency, speeds and load factors are all increased to generate higher pkm estimates. These are all checked against data on existing high-performing systems, with the idea that the future aver- age system would perform closer to today’s best systems.

A key aspect of the projections in the High Shift scenario is growth in urban rapid transit systems—particularly rapid transit such as metro, tram/light-rail (LRT), commuter rail and bus rapid transit (BRT) systems.

Given the assumptions made and scenarios compared, the main finding is that a high- transit, high-non-motorized-vehicle scenario that (at least in the developing world) provides similar total mobility (in passenger kilometers) as a baseline, more car-dominated scenario, is likely to be more equitable, less expensive to construct and operate over the next 40 years, and to sharply reduce CO2 emissions. Unmanaged growth in motor vehicle use threatens to exacerbate growing income inequality and environmental ills, while more sustainable transport delivers access for all, reducing these ills.

—Replogle and Fulton

Cutting emissions across the world’s cities.

Transportation in urban areas accounted for about 2,300 megatons of co2 in 2010, almost one quarter of carbon emissions from the transportation sector. Rapid urbanization—especially in fast developing countries like China and India—will cause these emissions to double by 2050 in the business-as-usual scenario. Among the countries examined in the study, three stand out:

• United States: Currently the world leader in urban passenger transportation CO₂ emissions, the US is projected to lower these emissions from 670 megatons annually to 560 megatons by 2050 because of slowing travel growth combined with sharp improvements in fuel efficiencies. But a high shift to more sustainable transportation options, along with fewer and shorter car trips related to communication technologies substituting for transportation, could further drop those emissions to about 280 megatons.

• China: CO₂ emissions from transportation are expected to mushroom from 190 megatons annually to more than 1,100 megatons, due in large part to the explosive growth of China’s urban areas, the growing wealth of Chinese consumers, and their dependence on automobiles. But this increase can be slashed to 650 megatons under the High Shift scenario, in which cities develop extensive clean bus and metro systems. The latest data show China is already sharply increasing investments in public transport.

• India: CO₂ emissions are projected to leap from about 70 megatons today to 540 megatons by 2050, also because of growing wealth and urban populations. But this increase can be moderated to only 350 megatons under the High Shift scenario by addressing crucial deficiencies in India’s public transport.

Under the High Shift scenario, mass transit access worldwide is projected to more than triple for the lowest income groups and more than double for the second lowest groups. This would provide the poor with better access to employment and services that can improve their livelihoods.

The study was funded by the Ford Foundation, ClimateWorks Foundation and Hewlett Foundation.

Resources

• Michael A. Replogle and Lewis M. Fulton (2014) “A Global High Shift Scenario: Impacts And Potential For More Public Transport, Walking, And Cycling With Lower Car Use”