Passenger-miles per gallon (pmpg) is a metric for comparing passenger vehicle travel across modes. Transportation system efficiency increases as the number of passengers increases or as the vehicle fuel economy increases for each transportation mode. Data are from table 2.13 of the Transportation Energy Data Book.
| Vehicle | mpg* | Passengers | pmpg |
|---|---|---|---|
| Car | 28 | 1.5 | 43.1 |
| Pickup Truck | 20.6 | 1.8 | 37.4 |
| Motorcycle | 42.3 | 1.2 | 50.7 |
| Transit Bus | 3.4 | 7.5 | 25.9 |
| Transit Rail | 6 | 23.6 | 141.4 |
| Intercity Rail | 3.4 | 23.2 | 79.8 |
| Commuter Rail | 2.2 | 33.9 | 76 |
| Airlines** | 0.4 | 120.4 | 53.6 |
* All fuel converted to gallons of gasoline on an energy content basis. For trains, most of this fuel is electricity.
** Domestic flights only. All fuel use is attributed to passengers, none to cargo that might be using the same airplane.
Public transportation in the United States includes buses, bus rapid transit, trolleys, rail, and ferries. Transit buses are particularly well-suited for alternative fuels, and nearly 60% run on these lower-emissions, cost-saving options. Since transit buses can carry more passengers, they have the potential to achieve a higher passenger-mile per gallon. Dedicated bus lanes are a key method to increase the efficiency of public transit and deliver a higher quality of service that increases ridership. Emerging technology allows for automating the enforcement of transit right of way. For example, in July 2023, Washington, DC, began using automated cameras to keep some bus lanes clear. Additionally, policy strategies can be used to incentivize public transportation and other multimodal solutions, including holistic parking policies that transfer the cost of parking land and infrastructure to those that are using it.
Ridership determines the quality and impact of public transportation, while improved quality can increase ridership. The relationship between high ridership and increased service frequency and efficiency can lead to reduction in vehicle miles traveled (VMT), congestion, and fuel used by private vehicles. The COVID-19 pandemic had a dramatic impact on public transit ridership, revenue, and operations, though many frontline and essential workers continued to use public transit to travel to their jobs. The Bipartisan Infrastructure Law of 2021 allocates funds to support the recovery of public transit operations and address four priorities: safety, modernization, climate, and equity. Corporate decision makers and transportation planners can use the following strategies to help build strong ridership.
Increasing the convenience of public transportation can boost ridership. Dedicated or “bus rapid transit” lanes and the use of high occupancy vehicle (HOV) lanes can reduce travel time for public transit riders. Effective public transportation is also more convenient when it is predictable. Public transportation providers can make their services more predictable by publishing schedules and communicating status updates. Updating service status often and providing those updates via easily accessible mobile applications such as Google Maps also increases predictability. Some public transportation providers use geotracking systems such as NextBus to help riders track schedules and delays. Public transportation providers can also make their services more convenient by offering flexible payment options such as app-based services that integrate payment for a range of mobility options, such as micromobility and ride hailing, as part of a common payment platform.
Another way to facilitate public transportation ridership is to help people complete the first or last leg of their trip and get to the transit stop. Helping passengers link multiple transportation modes is key. Some public transportation agencies offer mobile ticketing apps or pre-loaded transit cards. In some cases, these are interoperable with bike sharing systems or other micromobility services. Making bicycle or scooter storage available on buses or at transit stations can also enable travelers to move between transportation modes easily. Public transportation agencies are also forming partnerships with transportation network companies and micromobility providers to improve mobility choices for customers. Agencies in rural areas are finding that on-demand shuttles can improve convenience and reduce fuel use in areas with low population density.
Park-and-ride lots are strategically located near roads widely used by commuters and are often near transit stations. These lots are convenient places to meet rideshare partners or switch transportation modes to public transportation. Transportation planners can help commuters take advantage of park-and-ride lots by making information easy to access online. For example, Denver’s Regional Transportation District (RTD) website provides interactive maps of park-and-ride lots and a list with information about fees, parking spaces, and transit connections. “Kiss-and-ride” lots and lanes facilitate the quick transfer to and from public transportation and a waiting vehicle.
A growing number of employers are offering mobility benefits as part of an emerging trend to incentivize or otherwise support employees to explore energy-efficient commuting options. Employee mobility benefit packages may include a variety of options, including free or subsidized transit passes and memberships to micromobility systems.
Employees may benefit from such programs through reduced commuting costs, reduced parking costs, reduced need for vehicle ownership, and the ability to reclaim time that would otherwise have been spent piloting a vehicle. Employers may benefit from being in a stronger position to recruit and retain labor talent, reduce investments for private car parking, and project a tech-savvy energy-conscious image. Employee passes and transit subsidies are effective incentives for corporate decision makers to build mass transit ridership, conserve fuel, and reduce VMT. Employer compensation for transit may have tax benefits. Learn more about such commuting benefits from the U.S. Internal Revenue Service.
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