Our central finding is that while vehicle electrification and automation may produce potentially important benefits, without a corresponding shift toward shared mobility and greater use of transit and active transport, these two revolutions could significantly increase congestion and urban sprawl, while also increasing the likelihood of missing climate change targets.

In contrast, by encouraging a large increase in trip sharing, transit use, and active transport through policies that support compact, mixed use development, cities worldwide could save an estimated $5 trillion annually by 2050 while improving livability and increasing the likelihood of meeting climate change targets.

—Fulton et al.

The new report builds on two earlier reports published by ITDP and UC Davis’s STEPS (Sustainable Transportation Energy Pathways) program: “A Global High Shift Cycling Scenario” (2015) and “A Global High Shift Scenario: Impacts and Potential for More Public Transport, Walking and Cycling with Lower Car Use” (2014). Both reports took a scenario approach to consider the role of different travel modes in providing mobility, and the amount of potential energy savings and CO₂ reduction that could come from a less car-centric world in the future.

(STEPS is a multidisciplinary research consortium, part of the Institute of Transportation Studies at UC Davis.)

The new report considers the role of electrification, automation, and ride sharing (more people per vehicle). The study is global, breaking the world into eight regions including five major markets: United States, Europe, China, India, and Brazil.

Key findings included:

• The 2R scenario may provide significant energy and CO₂ savings, but mostly after 2030, and only with large-scale decarbonization of electricity production. In the 2R scenario, vehicle travel rises higher than in the BAU, but vehicle-related emissions and energy use are eventually cut significantly, with specific CO₂ reductions dependent on the extent to which electricity production decarbonizes around the world. If the world’s electricity production is not completely decarbonized by 2050, this scenario may produce more CO₂ emissions in 2050 than is consistent with targets to limit global temperature rise to 2°C (or less) compared to preindustrial levels.

• An autonomous vehicle (AV) world without electrification (i.e. using ICEs) and without trip sharing would not cut CO₂ emissions out to 2050. The researches estimated that the lower travel time “costs” provided by self-driving vehicles would likely lead to a significant increase in vehicle travel—15-20% compared to the BAU (with a wide range of uncertainty). The increased efficiency of AVs would offset some or all of this travel to keep energy and CO₂ close to BAU levels. The increased travel of AVs could trigger more traffic congestion, although their improved road-space efficiencies and coordinated travel patterns might mitigate some of these impacts.

• The 3R scenario performs significantly better on energy and CO₂ , as well as on livability. This scenario has the potential to deliver an efficient, low-traffic, low-energy, and low-CO₂ urban transport system around the world. In this scenario, the widespread adoption of on-demand travel with substantial ride sharing, along with greater use of (high-quality) public transport, cycling, and walking reduces car travel by well over half in 2050, and the number of cars by nearly three-quarters compared to the BAU.

• Ride sharing must deliver high-occupancy-vehicle travel, both in light-duty taxi-style vehicles and in some larger vehicles such as minivans and small buses. Ride hailing services do not help bring about this scenario if they are dominated by single-occupant trips. Assumed load factors (average passengers per trip) in ride-hailed vehicles rises over time in the 3R scenario and is about 30-40% higher than in the 2R or BAU scenarios by 2050.

• The 3R scenario also delivers large cost savings.

• The 3R scenario achieves its energy, CO₂ and cost savings by creating a far more efficient transportation system than in the BAU or 2R scenarios.

• The 3R scenario would also significantly reduce the number of vehicles on the world’s roads by 2050. The current global urban stock of LDVs, around 750 million (out of 1.1 billion total, urban + non-urban), reaches 2.1 billion by 2050 in the BAU and 2R scenarios. In the 3R scenario it drops to about 500 million.

The authors noted that the 3R scenario will require strong additional support for ride sharing, public and active transport, and land-use planning that helps to shorten most vehicle trips. Further, in 3R, governments play a central role.

Resources

• Lew Fulton, Jacob Mason, Dominique Meroux (2017) “Three Revolutions in Urban Transportation”