Fuel efficiency of trains no better than cars?

MichaelBluejay · 2008-09-09 03:41:22

I was floored to recently discover that trains get only about 43 MPG per passenger -- worse than a Prius (46 MPG). And of course, if you put two people in the Prius, then the Prius pMPG doubles. Heck, you could put two people in a 22 MPG car and then do better than the train.

It seems there are two reasons for trains' poor performance. First, they're often heavier than cars on a per-passenger basis, so they take almost as much fuel to run. (Not quite as much, since there's some efficiency from running on a fixed track vs. a road.) Second, there are usually lots of empty seats.

This doesn't mean that people should feel justified taking their car instead of the train just because the reported MPG is similar. That's because if they take their car they're definitely burning a lot of extra fuel, while the energy of the train is practically "free" because it's going anyway. And of course, there are 100 other reasons why trains are better than cars for the environment and for society.

Still, it's kind of a frightening thought that if we replaced all current passenger train trips with high-MPG car trips, the energy use could be similar. I thought trains were supposed to save us, not Priuses.

By the way, highway buses are reported to get 148 pMPG, and several sources give about 48 pMPG for airplanes. Here are sources for trains:

Wikipedia. 33pMPG for cars, 41pMPG for transit rail -- and cars' figures will get better as people keep ditching SUVs

U.S. Passenger-Miles Per Gallon. 45 pMPG for Amtrak. Incredibly detailed monograph by David Lawyer.

Vermont Rail Advocacy. Says that Amtrak uses 21% less energy than cars. Cars thus break even once fuel efficiency goes from the current 22 MPG to just 27 MPG.

Rail vs. Auto Energy Efficiency. Another detailed article by David Lawyer.

Energy efficiency of different modes of transportation, by James Strickland. He gives much higher figures for train MPG, but I think he might be using higher-than-average train capacities.

doughead · 2008-09-09 09:40:48

Unless there is a global financial / social meltdown the private use of the automobile is not going away anytime soon. In Texas we have the most inefficient use of resources on the planet so we have more room to keep the autos on the road with minor adjustments in efficiency. New York city recently made changes in their development codes to allow for more parking in downtown New York. The car is not going away it is going to get smaller and more efficient.

chavela · 2008-09-09 16:22:41

What trains are these? Our European friends were here, and when they saw the Amtrak train, their response was "Oh, how quaint--like the trains we used to ride when we were young!" Maybe our trains aren't the most efficient because they are older design.

MichaelBluejay · 2008-09-10 01:03:20

Okay, Chavela, good point -- American trains are likely less efficient than those elsewhere, because everything in America is less efficient. In this case, the culprit is probably not enough passengers. By contrast, in Japan the trains run lots of passengers all day and all night, not just during rush hour. David Lawyer says Japan rail travel is "a few times" more efficient. If by "a few times" we assume 3x, then suddenly trains are way in the lead. Wikipedia says Japan trains use 0.35 MJ per passenger kilometer, which works out to 235 pMPG! Maybe they're overestimating somehow, but even if they were off by a whopping 50%, then their trains are still about 3x more efficient than ours.

m1ek · 2008-09-22 16:28:52

Full light rail trains do very well on efficiency - and this is from a guy who now owns TWO Priuses. To say nothing of the fact that the Prius usually has only one person in it as well.

Also, electrified rail can be run off a much larger array of power sources than can rubber-tired vehicles. The Prius can't be charged by electricity, and someday down the road when its successor can be, the efficiency will be less than for a train run by overhead wires due to losses inherent in batteries.

Last edited by m1ek (2008-09-22 16:33:12)

marcus · 2008-10-23 15:46:36

I would say that just measuring fuel efficiency without looking at everything else the "world of cars" has wrought seems like a poor way to measure.

mashirts · 2009-01-02 11:26:59

You can't beat steel to steel for keeping down on road resistance.

mashirts · 2009-01-02 11:34:28

And most of the energy used for a car is pushing the air away: which goes right back into place for the next auto to push away.

dougmc · 2009-01-02 13:46:58

mashirts wrote:

And most of the energy used for a car is pushing the air away: which goes right back into place for the next auto to push away.

Not to be confused with a bike, where most of the energy used is used to push the air away: which goes right back into place for the next bike to push away.

For a train, a lot of the energy is probably used to push the air away: which goes right back into place for the next train to push away, though of course a lot goes into rolling friction on the track. I don't know what the ratio between the two is. In any event, as I understand it, the rolling friction experienced by trains on train tracks is about 1/10th as much as it would be with rubber pneumatic tires (which is basically what you just said.)

Done properly, a train should be much more efficient (i.e. moving X lbs of cargo or people to a point Y miles away, with the efficiency being (X * Y / energy required)) than a car. But of course, it's not always done properly.

seth · 2009-01-02 14:01:24

Trains are a long-term investment. Not immediate. But our countrymen have difficulty understanding this concept and how it relates to everything that matters.

Seth

rich00 · 2010-01-24 14:22:33

It really doesn't make much of a difference how little rolling resistence a train has. They are just so massively heavy that they require enormous amounts of power to get moving. I always wondered why passenger trains had to be so heavy? Is it neccessary for each car to weight 100,000-200,000 lbs?
And especially when you consider that most trains don't use regenerative braking technology, I don't know how anyone could consider a train as efficient.

I see much room for improvement, but then again, I'm not a professional engineer.

Zub · 2012-04-04 20:36:05

I work for a major railroad, and I love trains. The fuel efficiency of a freight train is about 1 gallon of diesel to move 1 ton of freight 500 miles, which is over 3 times the fuel efficiency of trucks. However..., the fuel advantage (and the overall competitive advantage) starts to drop with lighter products that have a lower "load factor" (number of truckloads that a railcar can carry. Heavy bulk products load 4.5 truckloads per railcar. String together 130 cars, and you have a train carrying 585 truckloads.

In constrast, passenger rail is a different story. A passenger railcar has just a few more seats than a bus, and passenger volume isn't usually sufficient to fill more than 8 railcars; so a passenger train carries only about 9 busloads. Greyhound averages 170 passenger miles per gallon, while Amtrak only gets about 55 passenger miles per gallon. This doesn't even consider the wasted fuel by freight trains idling on sidings to clear the way for Amtrak.

There is a misperception that the US rail network has excess capacity, but most main lines are maxed out. Passenger rail only makes this worse, with no net economic or ecological benefit. Because of passenger trains' higher speeds and priority status, they consume many times the main line capacity of a freight train, all for 9 busloads of people???? Amtrak restricts and delays freight shipments, forcing freight onto the highways.

Please, educate your fellow citizens and politicians. If mass transit is the goal, let's focus on a new, comfortable, economical, and efficient inter-city bus system so we can keep the freight where it belongs.

MichaelBluejay · 2012-04-04 21:32:26

Well, I'm not convinced that we have to pit good passenger rail against good freight rail -- why can't we have both? This country had healthy passenger rail back in the 19th century. It ought to be possible.

And buses will never be as comfortable as trains.

Zub · 2012-04-05 20:43:25

I wish you were right, but passenger service consumes a tremendous amount of rail line capacity. Imagine a 2 lane road with a speed limit of 45 mph, but an emergency vehicle has to make a long run on that road at 60 mph, and it must not stop or slow down. Railroad dispatchers have to clear the path well ahead of Amtrak just to make it fit. Freight crews hit their 12 hr max waiting for Amtrak to pass, and their trains "die" on the line of road. In addition, track engineering for passenger and freight service is very different, and track that accommodates both is a compromise that is good for neither.

My career has been railroad sales and industrial development, and Amtrak has as very real and significant negative effect on freight business. It deteriorates freight service, sending freight to the highway, and limits capacity for new business.

The healthy passenger era to which you refer was before cheap airfare and our interstate highway system. If you chose to research it, find a passenger rail rate from the 50's, adjust it for inflation, and compare it to the speed, cost, and convenience of today's highway or air options. It won't measure up, and that's why passenger rail has lost it's advantage. Amtrak's operatiing cost (not including lost freight cost to railroads) is $3.74 billion for 29 mm passengers. $130 per passenger buys a very nice bus with plenty of room, probably even a sleeping compartment. Heck, if I pool a few friends, I can ride in a limousine for less, and I'll be reducing my carbon footprint.

Last edited by Zub (2012-04-05 20:45:22)

MichaelBluejay · 2012-04-05 21:14:56

(1) You're assuming that passenger and freight have to share the same tracks. That's the way we're doing it here, but it doesn't have to be that way. Passenger and freight are segregated in most countries, just not here -- yet.

(2) Every time I've ridden on Amtrak, it's Amtrak who's had to wait for the freight trains to pass, not the other way around. Unless the conductors were lying to us.

(3) Your $130 figure per passenger for the bus is weird. You don't mention what distance trip this is for, and there's no way that a sleeping compartment would be provided at that price for all but the shortest trips, and even then the passenger miles per gallon would plummet, and start looking comparable to the pMPG for trains.

Rail works well in other countries, so the problem doesn't appear to be inherent in rail. The problem seems to be how we've chosen to implement rail here.

Bicycle Austin forum

#1 2008-09-09 03:41:22

Fuel efficiency of trains no better than cars?

#2 2008-09-09 09:40:48

Re: Fuel efficiency of trains no better than cars?

#3 2008-09-09 16:22:41

Re: Fuel efficiency of trains no better than cars?

#4 2008-09-10 01:03:20

Re: Fuel efficiency of trains no better than cars?

#5 2008-09-22 16:28:52

Re: Fuel efficiency of trains no better than cars?

#6 2008-10-23 15:46:36

Re: Fuel efficiency of trains no better than cars?

#7 2009-01-02 11:26:59

Re: Fuel efficiency of trains no better than cars?

#8 2009-01-02 11:34:28

Re: Fuel efficiency of trains no better than cars?

#9 2009-01-02 13:46:58

Re: Fuel efficiency of trains no better than cars?

#10 2009-01-02 14:01:24

Re: Fuel efficiency of trains no better than cars?

#11 2010-01-24 14:22:33

Re: Fuel efficiency of trains no better than cars?

#12 2012-04-04 20:36:05

Re: Fuel efficiency of trains no better than cars?

#13 2012-04-04 21:32:26

Re: Fuel efficiency of trains no better than cars?

#14 2012-04-05 20:43:25

Re: Fuel efficiency of trains no better than cars?

#15 2012-04-05 21:14:56

Re: Fuel efficiency of trains no better than cars?

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