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Trains, Planes, or Cars: Which is the Most Carbon-Efficient Way to Travel?

St. Paul Empire Builder

A GE Genesis in 40th-anniversary Phase I paint leads a stub Empire Builder out of St. Paul, Minnesota after floods suspended service west. (2011)

Many of us traveled for the holidays, and many of the Streets community shared their experiences of traveling by Amtrak.

It is very true that when moving on flat ground in a straight line, trains on steel wheels and rails are the most efficient form of transportation. Rolling on steel rails reduces rolling resistance and traveling at slow speeds (compared to jet aircraft) reduced the force of air resistance.

Amtrak has a whole page on its website dedicated to touting its green credentials. It boasts that “Amtrak is 47 percent more efficient than traveling by car and 33 percent more efficient than domestic airline travel on a per-passenger-mile basis.”

Energy use for different forms of transportation

Source: Transportation Energy Data Book, Edition 37.1, 2019 via Amtrak

But the question becomes, what happens when the route is not a straight line? Many of Amtrak’s routes take natural paths through mountains and hills and forests, and don’t follow the direct path of a jet aircraft at 30,000 feet.

The route of Amtrak’s Empire Builder highlighting sections of double-tracking.

I calculated statistics for three of the most popular inter-city routes, the Empire Builder from Chicago to Seattle, the Zepher from Chicago to San Francisco, and the Silver Meteor from NYC to Miami. Amtrak was compared to a jet flight and car trips for two types of passenger vehicles. I used available information for Amtrak route length and the Energy Department’s estimates for converting those British Thermal Unit numbers into carbon emissions from burning diesel for trains, jet fuel for aircraft, and gasoline for cars. The median fuel economy for new passenger vehicles is 24 miles per gallon in 2019, according to a survey by Consumer Reports, and a hybrid car gets about 45 miles per gallon.

Trip Airline Amtrak 24 mpg Car 45 mpg Car
Empire Builder (Chicago to Seattle) 1,730 miles 2,200 miles 2,036 miles 2,036 miles
284.56 kg 249.64 kg 904.27 kg 401.90 kg
Zepher (Chicago to San Francisico) 1,840 miles 2,438 miles 2,307 miles 2,307 miles
302.65 kg 276.65 kg 1,024.63 kg 455.39 kg
Silver Meteor (NYC to Miami) 1,090 miles 1,389 miles 1,298 miles 1,298 miles
179.29 kg 157.61 kg 576.50 kg 307.46 kg

As we can see, the routes that Amtrak takes are less efficient (the average of the three routes is about 29 percent farther), but this is offset by the great efficiencies of rail transportation. Across the three long-haul routes, the carbon emissions of transportation (not including meal service and other factors) is about 11 percent less than comparable air travel and far better than driving, even in a hybrid car.

An Amtrak conductor communicates with the train engineer at a station stop in Red Wing.

Offsetting the Carbon Footprint

The only downside to traveling by Amtrak is the time it takes to complete the route. On the Empire Builder from Chicago to Seattle, the 2,200-mile route takes 46 hours and 10 minutes for an average speed of 55 miles per hour, assuming no delays. A flight from Chicago to Seattle takes about 4 hours and 45 minutes for an average speed of 364 miles per hour, gate to gate.

What can the time-crunched traveller do? It is possible to offset your carbon emissions, and there are a growing selection of options to choose from. Most promise to invest your dollars into projects that either promote renewable energy or carbon capture programs, like planting trees. The cost of offsetting a flight from Chicago to Seattle may cost between $2.24 (Cool Effect, Inc) and $3.13 (terrapass), depending on the program you choose. That’s an easy price to pay for the convenience of air travel. It is important to do your research, as there are bad actors out there.

If you enjoy the leisurely journey, be sure to try Amtrak, and share your experiences with the Streets community!

12 thoughts on “Trains, Planes, or Cars: Which is the Most Carbon-Efficient Way to Travel?

  1. Bill LindekeBill LindekeModerator  

    It’s also true that many air trips are not non-stop flights. I.e., you might be flying to L.A., but stop in Denver along the way.

    That’s a big problem because a huge percentage (40%?) of CO2 emissions from air travel comes just from takeoff and landing, not from the (more efficient) cruising altitudes. So that CO2 number is not quite accurate here for many travellers.

    See also: https://kottke.org/20/01/air-travel-in-the-age-of-climate-crisis-is-it-wrong-to-fly

    1. Mark

      Yet another reason to avoid ULLC airlines like Frontier. I’ll gladly pay extra to Delta, or another legacy carrier, to avoid a layover. Even better if it helps reduce CO2 emissions

  2. Henry PanHenry Pan

    I ride the Empire Builder at least twice a year, at least once out to Chicago and at least once out west to either Seattle or Portland. It’s a long trip but enjoyable!

  3. Liam Glover

    Are your carbon emission calculations for a car based on a fully occupied/weighted vehicle? Or is the emissions kg just for a single car, no matter the occupants?

    1. Monte Castleman

      Even if they’re using the average occupants per vehicle instead of one, it probably skews the statistics on long trips like these. Chances are you drive to work alone, but for multiple people on road trips like these there’s incentives to use a car, since you’re basically using the same fuel whether one person or four but going by plane or train your cost is quadrupled.

  4. Linnea

    Why isn’t the bus a part of this? I’ve seen other studies that say that bus is by far the most efficient way to travel.

    1. Monte Castleman

      It would be interesting to see the math if we packed ships full of steerage passengers like we use to do back in the day (and sort of do to coach airline passengers now). But today’s cruise ships where everyone has a private cabin have a high carbon impact, although mitigated somewhat by the fact that the cruise is your vacation- you’re not renting a car, staying in a hotel etc at your destination.

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