Does Traveling by Trains / Buses / Ferries Have a Lower Environmental Impact than Traveling by Air?

A picture taken from the boat deck of the M/V Kennicott

Right now I am aboard the M/V Kennicott, a boat, en route to Whittier, Alaska (though, due to the lack of internet in the middle of the Inside Passage, this post is going to be published much later). One of my principles for this trip to Alaska is that I will not board any flying vehicle unless it is urgent. When people hear this, almost all of them start talking about how this type of travel is so environmentally friendly. I’ve already discussed the reasons to travel this way which don’t have anything to do with the environment. So now the question: does this form of travel have a lower environmental impact than flying in a plane?

Let’s start with the boat, since I’m on it as I type this.

When people think ‘environmental impact’ they usually mean ‘carbon footprint of fuel burned’. This is just one type of environmental impact among many, but since this is what is on people’s minds, I’ll start here. I know that boats generally require less fuel to carry the same weight over the same distance compared to land or air transportation. Based on that information, one might assume that this ferry has a lower carbon imprint than trains, buses, and airplanes. However, this ferry also offers many services/amenities that those other forms of transportation typically do not offer like: lots and lots of space to move around, a cafeteria, microwave and unlimited hot water for passenger use, showers for ALL classes of passengers of unlimited length. All of these amenities seems luxurious to someone who is accustomed to train/bus travel, but I am sure they require consuming more fuel. Oh, and this vessel also has stabilizers, which reduce fuel efficiency.

According to this chart, the M/V Kennicott has a service speed of 16.75 knots, or 19.28 miles per hour, and it consumes 354 gallons of diesel per hour. It has a capacity of 450 passengers, but when I went from Washington to Alaska, there were only about 80 passengers. It also carries vehicles and freight, but I’ll disregard that. If there are 450 passengers, then the fuel efficiency is 24.41 miles per gallon of diesel per passenger. If there are 80 passengers, then the fuel efficiency is 4.34 miles per gallon of diesel per passenger. By comparison, my dad’s old car got 40 miles per gallon of gasoline (not diesel!) when it was driving at freeway speeds and was not carrying much weight (with five people in the car, the fuel efficiency would drop a bit, but not below 35 miles/gal at freeway speeds). Obviously, taking into account that the ferry carries vehicles and freight in addition to passengers will make the fuel efficiencies look better, but I doubt a fair reckoning would make the ferry look more fuel efficient than my dad’s old car. I could argue that the ferries would run whether I was on them or not, and thus by choosing to ride the ferry I’m not meaningfully increasing fuel consumption, but the same argument could be made for airplanes which are below maximum capacity yet going to fly anyway.

I’ll brainstorm other environmental impacts: this ferry discharges wastewater directly into the sea; this ferry possibly disturbs wildlife; this ferry requires ports/docks which disturb the land where they are built; the construction and maintenance of this vessel must require a lot of resources; there must be a limit to how many boats can use the Inside Passage safely at the same time; there is a risk that this vessel will sink in such a way that it will cause additional environmental damage. We passed Bella Bella; I’ve heard that some kind of boat crashed there in recent years and leaked a lot of oil which caused a lot of harm to the local ecosystem (update: now that I have internet again, I found a news article about this). For that matter, this vessel will cross the very same territory where the Exxon Valdez had its infamous accident.

A picture I took of Bella Bella in the Heitsuk Nation as we passed by.

I’ve done a lot more research on the environmental impact of trains. At first, I also focused on fuel efficiency, with particular attention to carbon. I had assumed that they were much better than airplanes in this regard, but I wanted specific information to back that up. However, the more I researched, the less certain I became. That is because TRAINS ARE DIVERSE. There are many kinds of trains operating in the world, and they vary widely in fuel efficiency and carbon intensity. First of all, trains use many different fuel sources. Coal? Diesel? Biofuel? Electric – and if so, where does the electricity come from? That is just the beginning of how complex it is to figure out what the environmental impact of trains based on fuel usage alone is. And then there are other factors, such as weather (which effect the performance of train tracks), the grade, and so forth.

After I finished researching, I came to the conclusion that generally, trains have lower carbon intensity per unit of distance that airplanes, BUT for a train system like Amtrak, the carbon intensity is not dramatically lower, especially for the diesel Amtrak trains (i.e. all of the Amtrak trains I have ridden). Since the Amtrak network itself is diverse, I expect that there is much variation is the carbon intensity of different Amtrak lines under different weather conditions. I have also come to the conclusion that anybody who claims that trains only have 1/10th of the carbon impact as airplanes to cover the same distance is cherrypicking their data/interpretations to make the trains look as good as possible. A study which looks at specific train lines for fuel efficiency and/or carbon intensity may be reasonably accurate; if the specific train lines are not listed, I am very doubtful of the accuracy. (If you’re curious, this is what Amtrak says about its own carbon footprint).

And then there are all of the other environmental impacts of trains. A big one is land use impact. Trains require lots of tracks, and tracks have a very high land use impact. Airplanes also have a land use impact; airports have a very high land use impact where they are located. But the overall land use impact of airports is much lower than the land use impact of train tracks. That is why there are ecological preserves where all ground vehicle transportation is forbidden or highly restricted, but airplanes and helicopters are permitted. For example, if you are trying to provide transportation in a forest, creating a landing strip for airplanes/helicopters requires cutting a lot fewer trees than cutting a passage for train tracks to get in/out/around the forest.

A lot of what I said about trains also apply to buses, though buses tend to share roads with many other uses, so much of the land use impact of roads cannot be applied to the buses.

However, insisting on surface transport (boats, trains, buses) and refusing air travel does greatly reduce the fuel consumption and other related environmental impacts in a big way – but not the way which is obvious to most people I know. The real reduction in environmental impact is not in fuel consumption per kilometer traveled. The real reduction is in traveling fewer kilometers.

About ten years ago, I read an essay which explained that, when you examine how city buses are actually used within a metropolitan area rather than how they work in idealized scenarios, their fuel efficiency per kilometer traveled was about the same as using a small car to get around the metropolitan area. However, when people do not have their own cars, they will generally travel fewer kilometers, and the better the local public transit system is, the more people will choose to live without a car. Thus, a good public transit system reduces consumption of fuel not by being more fuel efficient than personal vehicles, but by reducing the number of kilometers that people travel.

I can’t find that essay again, and I don’t know whether its conclusions were based on good data, or reasonable interpretations of the data. But after having done some of my own research into trying to compare the environmental impact of airplanes vs. trains, I have come to the conclusion that, even though trains probably are modestly more fuel efficient (and less carbon intensive) than airplanes, that does not make nearly as much of a difference as traveling shorter distances. And by ruling out air travel, I am putting a hard limit on how far I can travel per day, and because my time for travel is limited, it effectively limits how many kilometers I travel.

Excluding air travel means I do not travel all of the way to New Zealand (which is very far away from San Francisco). It means that I delayed traveling to Alaska for years. It means that this trip to Alaska is the first time since the year 2014 that I have traveled such a long distance (the distance I am traveling by ferries in ONE direction is greater than the distance from San Francisco to Miami, Florida, and that is not including train/bus travel).

I could get similar results just by putting a quota on how many kilometers I may travel outside of the San Francisco Bay Area per year, even if I permitted myself to fly in airplanes. Personally, I prefer to restrict myself by excluding air travel over putting a numerical limit on kilometers of travel, but I don’t think I am being kinder to the environment than someone who does stick to a quota of kilometers of travel per year, even if they use up that quota by flying.

If I really wanted to cut my environmental footprint, I simply would not travel recreationally outside of the San Francisco Bay Area. I admit that, by choosing to engage in recreational travel, I am placing a heavier environmental footprint on this earth.

1 thought on “Does Traveling by Trains / Buses / Ferries Have a Lower Environmental Impact than Traveling by Air?

  1. Pingback: Living without Air Travel | The Notes Which Do Not Fit

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