It's sort of an accepted in truth in the environmental community that the environmental performance of rail is superior to that of other transportation modes. However, there's not a lot a real data on this, and it's usually couched in terms of "energy efficiency" which is a little bit different than actual emission levels. (There's also the issue of the environmental footprint of rail infrastructure as opposed to roads, airports, canals, etc, and the claim that rail might be better at enabling dense walkable urban centers that would be a viable alternative to suburban sprawl with its extremely negative ecological footprint.) Last January at the annual meeting of the Transportation Research board in Washington, I saw a poster which actually provided some real-world fuel consumption data for an Amtrak train, something I've never seen before. This was done by a team from the Civil Engineering Department at North Carolina State University, and their main goal was to see if they could model energy consumption of various run segments and perhaps be able to demonstrate that "eco-driving" techniques could result in significant reductions in fuel consumption. As fuel consumption is very strongly correlated to CO2 emissions and reasonably strongly correlated to NOx and PM emissions, their approach might be useful in evaluating the claim that trains are environmentally superior, at least from the standpoint of emissions. Here's the poster. You should be able to zoom it out to read the whole thing: The test train was the Piedmont service between Raleigh and Charlotte, with a particular emphasis on the Raleigh-Cary segment. The first thing that jumped out at me was a comparison of the fuel consumption of the different segments: The fuel consumption of the Raleigh-Cary segment averaged about 5 kg/diesel file per mile (+/- 1 kg/mi), whereas the other segments between Cary and Charlotte averaged about 3 kg/mile (+/- 1 kg/mi) The Raleigh-Cary segment ran at 0.6 to 1 mile per gallon (mpg), and the Cary to Charlotte segments ran at 1 to 1.9 mpg. The Raleigh-Cary segment is short relative to the segments between Cary and Charlotte, and a larger percentage of the run is involved in acceleration. There are also a couple of curves between Raleigh and Charlotte that require the train to slow down and then speed up, which means more acceleration. As anyone who tries to "eco drive" their car or truck knows, the more times you accelerate and the harder you do it, the worse the fuel consumption. To compare this to other modes, you have to know how may passengers the train carries. From somewhere on trainweb, I found that the consist of the Piedmonts are usually 2 - 4 coaches and a vending/baggage car. They have two types of coaches, one has 56 seats, the other has 66 seats. By the way, if I ride the Piedmont, how can I tell which coaches are the 56 seat coaches (which I think would have more legroom)? This means a maximum capacity of the train of 224 - 234 passengers. That means that on the Raleigh-Cary segment, the maximum possible fuel consumption is 134 - 264 passenger miles per gallon. On the Cary-Charlotte segments it's 224 - 500 passenger miles per gallon. The assumption is that the train is fully sold out, and, of course, the fuel consumption does not include was is needed for turning the trains, etc., as yard switchers don't run on fairy dust. In comparison with other transport modes, a single occupancy car with a fuel economy of 25 mpg, will get 25 passenger miles per gallon, and if there are 4 people riding in the car, it will get 100 passenger miles per gallon. I'm not sure what kind of fuel economy intercity motor coaches have now, but based on my work with 18 wheeler tractor trailers, I would expect they should be able to do 6 mpg. If a 50 seat bus is filled up, that would give them about 300 passenger miles per gallon. There are implications about this that I will post later, as I I need to go right now.