Thread by @asymmetricinfo

Huh. I was skeptical, but it seems that at average passenger loads, transit buses really are *less* fuel efficient than personal automobiles. afdc.energy.gov/data/10311

This article explains why: reason.org/commentary/doe…

(Full disclosure: it comes from the Reason Foundation, which also employs my husband at Reason Magazine).

How can this be? Because in most systems, the buses have to run mostly empty most of the time.

Typical peak-load trip: start at the periphery with very few passengers, pick up passengers until you're standing-room only, hit peak load at the edge of the central business district, and then slowly drop people off until you reach the end of the route nearly empty.

Note that even at peak hours, you're running *most* of the trip much less than full. And buses have appalling fuel efficiency.

The math is even worse at off-peak hours, though there are a few places--notably the denser parts of Manhattan and Brooklyn--where buses can run pretty full for much of the day.

Buses need to average 11 passengers over the whole trip to break even with a car carrying a single passenger. Most places just don't have that big a demand for the bus.

Now, that said, we can ask if there are counterfactuals. I.e. we can argue that right now, outside of NYC, bus service is too sporadic to reliably replace cars, so no one takes the bus, so passenger loads are low--and if we priced carbon/altered urban plans, that would change

Maybe. But there's a potential problem with trying to lure people away from a car-based lifestyle with buses: you're gonna need a lot of buses, running very often. Except *maybe* for commutes, a bus that comes once every 40 minutes isn't a good car replacement.

And commutes have this nice feature of everyone wanting to go roughly the same place at approximately the same time so you can really pack in the passengers.

Once you start trying to actually replace a car, you need to run buses really frequently, and since people aren't all trying to go to roughly the same place, you need a lot more sideways routes.

This makes it hard to get your load factors up.

The thing is, in NYC, which AFAICT is the only system that really just obviously beats cars, the bus often isn't even competing with cars, because you just can't jam many more cars into Manhattan.

It's competing with walking.

This is specific to parts of NYC and Brooklyn, but ... many's the time I'd start walking waiting for a bus, and by the time the bus actually came, though "To hell with it, I'm already halfway, I'll just walk the rest."

This is also the case where I now live in DC--obviously, again, quite specific to the area, as I live fairly close in. But the time difference between my bus commute and walking is negligible; if I really hustle, I can beat the bus.

(Then why do you take the bus? I hear you cry. Because I have a bad back and carrying a laptop bag a couple miles isn't good for it.)

Farther out, this is not the case. But then, farther out, the bus has to compete with cars, not Shank's Ponies.

There are, of course, other reasons than the environment to run buses. Also, it's quite possible that more fuel-efficient buses would change this equation--I mean, definitionally, they'd have to. But as it stands, buses are not the clear winners I'd assumed.

In closing, this is why we should get rid of all the buses and turn the nation's sidewalks into covered slidewalks. Robert Heinlein and Isaac Asimov predicted this 70 years ago and it's time for us to finally realize the dream. The future is now!