Green Tips #6 – Planes, Trains, or Automobiles?

Whether you’re planning a school trip, a family visit, or an upcoming holiday break, travel is often part of our lives. But how we travel matters, especially when it comes to caring for Earth, our common home. Every mode of transportation has a different environmental impact, and a major factor is the amount of greenhouse gas emissions it produces.

Let’s take a closer look at how different types of travel – cars, planes, trains, and buses – compare in terms of fuel efficiency and carbon emissions. This can help students, families and educators make more informed, sustainable choices.

To calculate the emissions from a trip, we need three things:

#1 Fuel Mileage: How far the vehicle can go on a gallon of fuel (mpg = miles per gallon).

• Gasoline car: 28.3 mpg
• Hybrid car: 50.0 mpg
• Domestic Flights (jet fuel): 0.50 mpg
• Transit Trains (diesel): 6.9 mpg
• Amtrak Trains (electric): 0.10 miles per kWh
• Transit Bus (diesel): 4.0 mpg
• Intercity Busy (diesel): 6.4 mpg

#2 Carbon Emissions per Gallon: How much pollution is created by each gallon of fuel.

Estimates are given below as pounds of carbon dioxide equivalents (CO2e) per gallon of gasoline, diesel, and jet fuel. (Note: the term carbon dioxide equivalents refers to the combined impacts of all greenhouse gases.)

• Gasoline: 20.86 pounds of CO2e
• Diesel: 22.45 pounds of CO2e
• Jet Fuel: 21.50 pounds of CO2e
• Electric: 0.81 pounds of CO2e per kWh

#3 Estimated Number of Passengers: Dividing emissions by the number of people traveling gives a better picture of your personal impact.

• Automobiles: 1.5 passengers per vehicle
• Domestic Flights: ~120.4 passengers per flight
• Amtrak Trains: ~169.6 passengers per train
• Transit Bus: maximum capacity = 60 to 90 passengers
• Intercity Bus: ~43.7 passengers per trip

So, What’s the Most Sustainable Way to Travel?

At first glance, cars might seem like the greener choice when it comes to travel — especially if you’re thinking just about fuel efficiency. But there’s more to the story. Trains and airplanes usually carry many more passengers, which means the carbon footprint per person is often lower than that of a car with only one or two people. In fact, unless you’re carpooling with at least three people, a typical car trip (excluding hybrids) can produce more emissions per mile than traveling by train or plane. Check out the breakdown below to see how the numbers stack up.

Individual Carbon Footprints Per Passenger

• Transit Trains (electric): 15 lbs CO2e per mile
• Amtrak Trains (electric & diesel): 26 lbs CO2e per mile
• Automobiles (hybrid): ~27 lbs CO2e per mile (based on the lower end of expected mileage for a 2024 Toyota Prius)
• Domestic Flights (jet fuel): 39 lbs CO2e per mile
• Automobiles (all fuel types): 48 lbs CO2e per mile
• Transit Bus (diesel): 80 lbs CO2e per mile
• Demand Response (includes Uber): 70 lbs CO2e per mile

Green Tips for Schools

As Mercy schools, we’re called to live out our Critical Concern for Earth in both word and action. Understanding the environmental impact of travel can help us plan school events and activities with care for creation in mind. Here are some ways schools can apply this knowledge:

• Plan greener school trips: When organizing excursions, consider choosing transportation with lower emissions. For example, a bus or train may be more sustainable than multiple cars or a flight. Estimate your travel emissions by dividing miles by fuel mileage, multiplying by emissions per gallon, dividing by number of passengers, and comparing totals across travel options.
• Start a classroom investigation: Have students calculate and compare the emissions of different travel options for an upcoming trip. This could be a great cross-curricular project involving science, math, geography, and Mercy values.
• Raise awareness in your school community: Create a campaign or display that helps students and families understand the impact of their travel choices. Encourage carpooling to school events or eco-friendly travel during breaks.
• Reflect on our Mercy call: Use this as an opportunity to talk about our shared responsibility to care for Earth. How can we be mindful travelers—choosing options that reflect compassion, sustainability, and justice?

Every school can make small changes that lead to meaningful impact. Let’s wrap our community—and our planet—in the Mercy spirit of thoughtful stewardship.

Sources

1. United States Department of Energy (2022)
2. United States Department of Energy (2025)
3. Bureau of Transportation Statistics (2025)
4. United States Energy Information Administration (2024a)
5. United States Energy Information Administration (2024b)
6. Oak Ridge National Laboratory (2022). “Transportation Energy Data Book Edition 40.”
7. Amtrak FY 2024 Company Profile