Over at KiwiReport, a writer named Serena Carsley-Mann asks a good question: “Why do trains in America function so different from trains in Europe?” Unfortunately, she mistakenly thinks the problem is that “trains in America function so badly.”

In fact, America has the most efficient rail system in the world. It is European trains that function badly. I’ve discussed this before in my blog, but since writers like Carsley-Mann continue to get it wrong, it is worth repeating.

According to a Pew study, freight shipped by truck uses about ten times as much energy, and emits far more greenhouse gases, per ton-mile than freight shipped by rail (see page 2). Because rail cars weigh more, per passenger, than automobiles, rail’s comparative advantages for passengers are much smaller, and unlike trucks it will be very easy for cars to close the gap: a Prius with a average of 1.67 occupants, for example, is more energy efficient than almost any Amtrak train. Thus, to save energy, it is better to dedicate rail lines to freight rather than to passengers.

This is what the United States has done, but it is exactly the opposite of what Europe has done. According to a report from the European Union, 46 percent of EU-27 freight goes by highway while only 10 percent goes by rail, while in the U.S. 43 percent goes by rail and only 30 percent by road. Thus, we’re using our rail system far more effectively than Europe. This is not just from an energy view but also from a consumer-cost view, as rails cost less than trucks for freight but more than cars for passengers.

Carsley-Mann actually sees freight trains as an obstacle to effective use of the railroads because the freight trains slow and sometimes delay the passenger trains. But in reality, it is the nearly useless passenger trains that are the obstacle to an efficient freight system. Europe manages to carry 5 percent of passenger travel on intercity rail lines, at the cost of pushing a huge share of freight shipments onto highways. By yielding most of that 5 percent of passenger travel to highways and airlines, American manages to free up the railroads for a huge amount of freight.

To avoid the freight conflict, some European countries are building rail lines exclusively for passengers. For the most part, the cost is very high and the benefits low. To some degree, subsidies to those rail lines attract people from lower-cost forms of transportation. But overall, rail is losing market share to cars and, especially, low-cost airlines, so Europe is fighting a losing battle. As economist Charles Lave wrote in The Atlantic many years ago, the “law of large proportions” dictates that “the biggest components matter most,” so making the cars that move 85 percent of people a little more energy efficient is more effective than getting a tiny share of those people out of their cars and onto trains that are a little more energy efficient.

Carsley-Mann never does figure out why American trains are so different from European ones. The answer is simple: American railroads are private and based on the profit motive they operate as efficiently as possible. European railroads are public and based on the political motive they operate as visibly as possible. Passenger trains are more visible to the public than freight trains (which are almost invisible to people like Carsley-Mann, who see them only as obstacles), so European politicians give their constituents subsidized trains rather than an efficient rail system.

I love passenger trains, but I prefer an efficient private system to a visible but heavily subsidized public system. Now if only we could privatize our airports and highways.