Ridesharing
Project Drawdown defines the ridesharing solution as: increased ridesharing when commuting in North America. This solution replaces the conventional practice of commuting in single-occupancy vehicles.
This research focuses its analysis on North America (defined as the US and Canada), where carpooling and ridesharing are most common and where car ownership and single-occupancy vehicle commuting rates are high. Ridesharing and carpooling are interpreted to be the same for this analysis: “the sharing of a car trip by the driver with a non-driver.” The terms are therefore used interchangeably. Although most Americans commute to work in personal vehicles, the percentage that carpools is relatively small, at 10 percent. This percentage is used for both countries. The fact that few people carpool to work means that there is high growth potential, if the benefits of ridesharing can be properly understood.
Methodology
In this study, carpooling is compared to single-occupancy car commuting. Cars represents the commuter mode for around 86 percent of all commuters in North America; hence, fewer than 9 percent of all commuters carpool (AASHTO, 2015; Toossi, 2012; Statistics Canada, 2011).
Total Addressable Market [1]
The total addressable market for carpooling is estimated as the total passenger-kilometers of commuting done by car in the US and Canada, using the average commuter driving distance.
Adoption Scenarios [2]
Impacts of increased adoption of ridesharing from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels. In each scenario, the average number of people in a carpooling trip increases from 2.31 to 2.5. [3]
- Plausible Scenario: This scenario projects that 15 percent of all car commuting is done by carpool in 2050.
- Drawdown Scenario: This scenario projects a more aggressive adoption, with 20 percent of all car commuting done by carpool in 2050.
- Optimum Scenario: The most optimistic case estimates 30 percent of all car commuting is by carpool in 2050.
Financial Model
As carpooling is defined here, there are no first costs to adopting the practice. However, an operating cost difference is included: with fewer cars on the road, the maintenance and fuel costs per passenger-kilometer are reduced, as they are assumed constant per vehicle-kilometer driven. [4] The average operating cost is divided by the average carpooling occupancy, which represents a 57 percent drop. The price of fuel is the average of the 10 years prior to our base year (2014), and comes from International Energy Agency (IEA) data.
Integration [5]
Besides ensuring that the same car inputs were used across relevant Transport Sector models (e.g. emissions factors, fuel economy, etc.), no special integration changes were performed in this model.
Results
The Plausible Scenario results in a total reduction of 320 million tons of carbon dioxide-equivalent greenhouse gases, and operating savings of US$186 billion. [6] The Drawdown Scenario shows a reduction of 360 million tons of emissions; in the Optimum Scenario, 3.2 billion tons of emissions are reduced.
Discussion
The financial costs of commuting are motivators for carpooling, but history shows that increased carpooling is driven most forcefully by external forces rather than by policies designed to promote carpooling. Carpooling in America became popular during World War II, when the federal government asked people to conserve resources for the war effort, and in the 1970s, in response to oil crises that sharply increased gasoline prices. Decreases in carpooling have occurred since then, despite gradual increases in fuel costs and the institution of policies, such as high-occupancy vehicle lanes, meant to encourage carpooling. Barriers to uptake include lack of flexibility and convenience and limited regulatory incentives. Motivators include economic, environmental, and social benefits: there is evidence that the latter two are becoming more important for the younger adult population.
Although the Drawdown model does not include the shift of transport mode share from single-occupancy vehicles to other options such as public transit, cycling or walking, it shows that carpooling can be part of a global shift towards more sustainable transport behavior. Behavior is often not discussed at climate change or sustainable transport fora—instead, the focus is often on technology—but with sufficient numbers, behavioral change can contribute to reducing greenhouse gas emissions.
[1] For more on the Total Addressable Market for the Transport Sector, click the Sector Summary: Transport link below.
[2] For more on Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Transport Sector-specific scenarios, click the Sector Summary: Transport link.
[3] This can happen with more 3-person and 4-person carpools.
[4] An additional person weighing 75 kilograms in a typical 1800-kilogram car increases the total weight transported by less than 4 percent, so wear and tear and fuel usage do not change much with more people.
[5] For more on Project Drawdown’s Transport Sector integration model, click the Sector Summary: Transport link below.
[6] All monetary values are presented in US2014$.
