Part 2: Environmental Benefits of Public Transit

In Ohio, transportation accounts for 31 percent of all carbon emissions, and is the second largest emissions sector after electric power (which accounts for 39 percent of state emissions). 10

Public transit can reduce greenhouse gas emissions by:

● Providing a low-emissions alternative to driving

● Facilitating compact land use, reducing the need to travel long distances

● Minimizing carbon footprint of transit operations and construction

Public transit on average produces 35% less carbon emissions than passenger cars. 11 Buses produce 32% less CO2 emissions than private automobiles, followed by light rail transit and commuter rails, which produce 60% and 63% less CO2 emissions, respectively. Finally, heavy rail transit and vanpools tie as the most energy-efficient public transit method, producing 76% less CO2 emissions than private cars.

Environmental benefits of public transit depend heavily on the number of passengers per vehicle, bus or train efficiency, and type of fuel used to power vehicles. The more passengers per vehicle, the more efficient and beneficial to the environment the vehicle is:

For instance, U.S. bus transit, which has about a quarter (28%) of its seats occupied on average, emits an estimated 33% lower greenhouse gas emissions per passenger mile than the average U.S. single occupancy vehicle. The savings increases to 82% for a typical diesel transit bus when it is full with 40 passengers.

Bus emission levels also depend on the type of fuels used. For example, hybrid-electric buses consume 15% to 40% less fuel/carbon emissions than diesel-fueled buses.

Lifecycle Emissions

Public transit is also much more sustainable than private automobile transit when taking into account the entire lifecycle of a transit system, from initial construction, to manufacturing, to ongoing maintenance. Examples include the construction of a highway vs. rail systems, or the cost to build and maintain cars vs. buses & trains.

Researchers at the University of California Berkeley studying various transit systems across the U.S. found that, while emissions from infrastructure construction has a greater impact on rail transit than automobiles, rail and bus transit still shows significantly greater emissions savings from average occupancy than average occupancy from sedans, SUVs, and pickups:

The researchers found that including greenhouse gas emissions from construction and maintenance of the [San Francisco] BART heavy rail transit system increases estimated greenhouse gas emissions per passenger mile from 64 grams to 140 grams, but that this still represents a 63% and 69% savings over travel by sedan and SUV, respectively.

Additionally, emissions per passenger mile are still significantly lower for public transit than for cars.

Compact Land Use

Public transit is also a much more sustainable alternative to cars because it fosters higher-density living, which conserves land and shortens distances to travel destinations. Without it, more land would be required to accommodate parking and travel lanes. An investment in public transit would mean a reduction in urban footprint and shorter trip lengths, contributing to an overall decrease in carbon emissions. Some studies show that for every additional passenger mile traveled on public transportation, auto travel declines by 1.4 to 9 miles. 12

Public transit also increases efficiency by facilitating “trip chaining,” allowing passengers to run multiple errands between stations. Additionally, since people who live near urban areas already tend to own fewer cars, an investment in public transit will likely lead to less car ownership. Fewer cars per household means reduced car use in general until cars eventually cease to become the habitual transit option.