Friday, October 16, 2009

Those efficient buses and trains?

Not really. Notice here that the Bureau of Transportation Statistics reveals that airline, bus, and automobile transportation all use about the same energy per passenger-mile as the passenger car. Interestingly, 3500btu/mile corresponds to about 30mpg, or a passenger sedan with slightly more than one passenger. Add the second passenger (or the 7th in my family's case), and the standard passenger sedan excels all other modes of transportation in efficiency.

Never mind the fact that it appears that the "source" for Amtrak's efficiency is a "personal note." No uncertainty in that one, of course. No fudging in the number of passengers carried or anything.

Note also that transit trains are not mentioned; given the frequency of starting and stopping, it would appear that these are most likely the worst of all modes of transportation in terms of fuel usage and emissions. Mass transit and mass transportation is many things, but "ecologically responsible" is not one of them.

5 comments:

pentamom said...

Well, you can't get seven people into a sedan.

But more seriously, is this assuming actual current ridership, or maximum ridership? If it's assuming actual current ridership, than what of the argument that mass transit would be more efficient if it was made more useful (i.e. better routes and schedules and so forth?) There are FREE downtown shuttle buses here in Erie that run around constantly with three people in them, but they're really pretty useless to people because few people live downtown and you have to have a car to get to the Park and Ride to get picked up, at which point there's no advantage to riding a bus around our relatively compact downtown (with adequate affordable parking.) Meanwhile, the paid buses in the rest of the city aren't useful because of overly limited times and routes.

So there's at least a case to be made that it would be possible to decrease per-passenger cost by increasing utility, and I suspect that apart from major cities with large non-vehicle-owning populations or limited and prohibitive parking, the situation here is pretty common. But if the figures you're quoting are assuming full capacity, then it's moot.

Bike Bubba said...

You could theoretically run buses and trains always at rated capacity (or at double, like in India sometimes), but people do tend to need some personal space. I'm guessing that the buses and trains are running about as full as they're going to get, at least until they drastically change the economic equation of travel.

(or like I'm always telling my kids; just because you "can" do something doesn't mean it's a good idea)

And even if they did drastically change the equations, full ridership on a bus that's empty 75% of the time (by design even) still only gets you the equivalent of about 60pmpg--about what you get in a decent car with two people.

And less than half of the 154pmpg my family's minivan gets in routine driving.

pentamom said...

Okay, your first paragraph answers my question. But I don't understand one thing you said:

"And even if they did drastically change the equations, full ridership on a bus that's empty 75% of the time " Come again? Full ridership, but empty? Please 'splain!

Anyway, by full ridership I didn't mean 100% full 100% of the time with no spaces, but something like you normally see in a big city system where the buses and trains do get full. But that was my fault for putting it that way, and not thinking it through. I was just thinking in contrast to my own experience where the running joke is "you can't say EMTA (Erie Metropolitan Transit Authority) without MT." Someone trying to assess the theoretical efficiency of transit based on the buses that never have more than 15 people on them except before and after school would be crazy.

Bike Bubba said...

You could have full ridership in the right direction during rush hour, but outbound in the morning, inbound in the evening, and off peak will still be largely empty. Hence even the best run systems will have, at best, about 75% of the seats empty--despite being packed going the right way during rush hour.

pentamom said...

Ah, got it. Thanks.