Silly Little Country

Brad Templeton Provides an Answer to One of My Questions

...in a fascinating essay.
My question was, "Why does everybody think that taking public transit is somehow more efficient than using cars?" There is a two-level answer. First, not everybody automatically thinks that. For example, I was always just agnostic. Brad is now clearly leaning one way. Now, note that his analysis is an average energy cost analysis per passenger mile; your decision on what to do on your next trip is one at the margin. (More on that below).

I was disturbed to learn that city diesel buses and electric trolley buses are both mildly worse than the car in energy efficiency. Light rail systems are also slightly worse, on average, though it varies a lot from city to city. Commuter rail and subway (heavy rail) trains tend to be a bit better, but not a lot better. (Non-hybrid cars are also better at long haul than they are short haul.)

It's worth reading the whole essay to see where the numbers come from and how reasonable the analysis tries to be without devoting a career to it. As for the marginal analysis:

In spite of them, it is always the green move for any individual to take existing mass transit over their car. That's because the transit is running anyway, so the incremental cost of carrying one more passenger is indeed less than just about any private vehicle. It is similarly green to carpool in somebody else's car that's going your way.

I found the link above in a post at Overcoming Bias.
In that post Robin Hanson wonders even about that:

I wonder. When one rides mass transit one not only makes the train a bit heavier, one also makes it a bit more crowded, discouraging other passengers. Worse, one makes all future transit planners estimate that a slightly higher fraction of the population is willing to ride mass transit, encouraging them to build more and large transit systems. It seems to me that this last effect could bring the marginal cost of using mass transit back up to near its observed average cost, i.e., about the same than cars.

As I tend to have time on my hands, I enjoy the social aspect of public transit in the city, though at the times where I value my time more highly, I will drive. Intercity, I still tend to drive, and that is a combination of valuation of time, and my freedom to choose my route..

posted by Alan Adamson @ 9:44 PM