By Susan Shaheen and Adam Cohen
Carpooling is undergoing a period of notable change. In recent years, advancements in technology, social networking, location-based services, wireless services, and cloud technologies are contributing to the growth of shared and on-demand mobility but also a renaissance in IT-enabled carpooling. While Americans are still heavily reliant on single-occupant travel, emerging services such as app-based carpooling are making it easier for travelers to share a ride. Pooling offers numerous societal, employer, and individual benefits. In this blog, we review ten key carpooling benefits.
Anecdotal evidence and research studies suggest that carpooling provides numerous societal benefits, such as:
1. Reduction in energy consumption,
2. Lower greenhouse gas (GHG) emissions, and
3. Congestion mitigation
Studies have found that carpooling can save fuel and reduce greenhouse gas (GHG)emissions for users and non-users (the latter due to reducing congestion on the rest of traffic). Each year, the average passenger vehicle consumes approximately 550 gallons of fuel (Noland et al. 2006). Carpooling can represent an important strategy to reduce fuel consumption. Another study estimates that if one additional passenger were added to every 10 vehicles, the U.S. could reduce fuel consumption by 7.54 to 7.74 billion gallons annually (Jacobson and King 2009). This study also estimates a savings of 68.0 million tons of GHG emissions annually in the U.S., if one passenger were added to every 10 vehicles. Another study estimates that carpoolers individually reduce personal commute GHG emissions by approximately 4% to 5% after joining an employer trip reduction program (Herzog et al. 2006).
Numerous studies assessing the impacts of employee trip reduction programs (including carpooling and a variety of other transportation demand management (TDM) programs) have found that employees participating in these programs report between 4% and 6% lower vehicle miles traveled than employees at the same worksite who did not participate (Herzog et al., 2006; Lagerberg et al. 1997; Boarnet et al. 2010). Other studies have estimated that carpooling can reduce regional vehicle miles traveled (VMT) by an estimated 1% to 2%, based on carpooling’s congestion mitigation impacts on the rest of traffic. However, it is important to note that carpooling could also lead to induced demand where people are encouraged to drive more due to reduced travel times and costs (Shewmake, 2018).
In additional to notable societal benefits, employers can also benefit from carpooling through:
4. Increased employee morale,
5. Reduced parking demand, and
6. Employer financial tax incentives for supporting carpooling
Anecdotal evidence suggests that employees who carpool may enjoy reduced commute stress and increased convenience associated with shared driving responsibilities, high occupancy vehicle (HOV)lane time savings, and preferential parking at worksites. These benefits can translate to increased employee morale. Additionally, by reducing the number of vehicle trips to a worksite, employers can reduce parking demand saving an estimated USD$15,000 to $45,000 per parking space in capital expenditures and USD$360 to $2,000 in operations and maintenance per a space. Finally, employers can take advantage of numerous state level commuter tax benefits and tax credits for carpooling. For example, in Washington State, employers and property managers who provide financial incentives to their employees for carpooling (along with other TDM measures) are allowed a credit up to USD$60 per employee (up to USD$100,000 annually). Maryland and Georgia have similar tax credit programs.
Individually, carpooling users benefit from:
7. Shared travel costs,
8. Travel time savings from high occupancy vehicle lanes,
9. Reduced commute stress, and
10. Preferential parking and other incentives.
While there are few published studies on the impacts of carpooling on individual travelers, empirical and anecdotal evidence suggests individual carpool users benefit from shared travel costs, travel-time savings from HOV lanes, reduced commute stress, and preferential parking and other incentives (Shaheen and Cohen, 2018). One study of casual carpooling in the San Francisco Bay Area found that convenience, time savings, and monetary savings were key motivators to carpool (Shaheen et al. 2016). In the Bay Area, commuters frequently use casual carpooling to get from the East Bay to downtown San Francisco during the morning commute. Using the HOV lanes of the San Francisco-Oakland Bay Bridge, carpoolers can take advantage of a toll discount and shorter waits at the toll plaza. According to a 1998 survey by the Metropolitan Transportation Commission, approximately 9,000 Bay Area commuters (6,000 riders and 3,000 drivers) used casual carpooling each morning. Another study of casual carpooling in Washington D.C. and Northern Virginia found that the top reason for choosing to be a carpool rider was the desire to save on the cost of gasoline, followed by a preference to do other things during the drive (Oliphant, 2008).
In the future, vehicle automation could result in higher average vehicle occupancies (due to shared fleet growth) or lower vehicle occupancies (from zero-occupant vehicles growth). The convergence of shared modes; mobile technologies, electrification, and automation will likely transform carpooling and other pooled services. While the impacts of automation are uncertain, what is clear is that policymakers support a culture of pooling through public policy today. This is necessary to prepare for an automated vehicle future tomorrow and to proactively mitigate the potential for VMT increases due to unoccupied vehicle trips in the future.
Susan Shaheen and Adam Cohen recently co-authored “The Benefits of Carpooling” and “Shared ride services in North America: definitions, impacts, and the future of pooling.”
Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.