At a recent presentation, the Antiplanner mentioned that transit is not energy efficient because most transit vehicles run nearly empty most of the time. A “gotcha” look appear on the face of an audience member, who said, “but what if more people rode transit?” Yes, and cars would be more energy efficient if they were filled to higher occupancies, the Antiplanner replied, and if pigs could fly, we could just ride around on pigs and we wouldn’t need to debate this at all.
Yet there are very good reasons why public transit occupancy rates will never rise much above their current levels of about one-fifth full. Suppose you take a bus or train to work during rush hour and it seems full. But it really only seems full as it approaches the center of town. It is likely to be nearly empty when it starts its journey in the suburbs, and be nearly full only when it gets close to the city center. Over a single, one-way journey into town (or out of town in the afternoon), the vehicle is likely to average only about half full.
Plus, that bus or train has to return in the other direction, and then it could be nearly empty. Now the transit line averages just one-quarter full. Add to that all the trips made during non-rush hours, and it is hard to imagine that transit vehicles can possibly average much more than one-fifth full.
As shown in the table, some kinds of transit do average more than one-fifth full. Van pools run during rush hour and are probably the only form of transit that are truly energy efficient. Cable cars are mainly a tourist attraction and run through the center of one of the densest cities in America. Puerto Rico’s Publicos are privately operated and go where they can make a profit.
Most forms of transit are not likely to replicate any of these very specialized cases. Even commuter trains, which often operate only a few in-bound trains in the morning and out-bound trains in the afternoon, average only 21 percent full.
Transit advocates have an interesting response to these facts. Buses are energy efficient, they say, if you count only rush-hour bus service. We run buses during other times only to meet other social goals, so we shouldn’t count the energy costs of transit during those times. Even if you believe this ridiculous argument, the chart on page 16 of this report is based on a hypothetical study of energy costs, while actual energy costs of buses and other forms of transit tend to be not significantly better (and in the cases of buses much worse) than cars.
The real significance of the lifecycle study quoted in the VTPI report is that the non-fuel energy costs of rail transit tends to be greater than the fuel costs, while the non-fuel costs of cars tend to be less than the fuel costs. “Current results show that total energy and greenhouse gas emissions increase by as much as 1.6X for automobiles, 1.4X for buses, 2.6X for light rail, 2.1X for heavy rail, and 1.3X for air over operation,” says the lifecycle study.
|Mode||Fuel Cost||Lifecycle Cost|
As shown in the table above, the high rail non-fuel costs cancel out the slight fuel-related energy savings of rail transit over cars. In any case, the only strategies that might make transit energy efficient are to run it only during rush hours or only in dense city centers–and even then there is no guarantee. Of course, there is a third strategy: privatize transit and let the private owners decide when it is efficient to run.