Recently, Randal O’Toole, who writes the blog The Antiplanner, wrote that mass transit will never be as energy efficient as personal vehicles due to low ridership. Much of his background data comes from a Victoria Transportation Policy Institute study which uses data from a 2008 study by UC Berkeley that examined the lifecycle emissions and energy inputs of light vehicles, buses, light rail, rapid transit and airplanes.
In preparing to discuss this, I have to admit my knee-jerk reaction was to reject O’Toole’s premise as ridiculous. However, as I dug further into the past studies that he references and the information I’ve reviewed in assembling the Clean Mass Transit report, a lot of what he says has merit, and he makes an interesting point. The fact is that the total energy cost of many forms of mass transit is substantially higher than individual cars on a per vehicle basis.
If we think about this on a very basic level, buses are big. They take a lot of energy to build and move once built; they are also much harder on roads because of their weight. Cars in comparison are small, they take less energy to build and move, and have relatively little impact on the roads. The energy required to dig subway tunnels or move heavy trains is substantially more than a car, as well. Making a train or bus energy efficient is a challenge just from the sheer physics of problem.
Of course, the problem is not that simplistic. The physical size challenge is only one of the inputs. Cars need freeways and have to be parked somewhere, while trains need platforms and tracks. According to the UC Berkeley study, the energy consumed over the life of each type of vehicle is:
While this makes sense, the challenge lies in then extrapolating this to the entire system. Assuming that energy consumption per vehicle would have to be applied to each vehicle in the system, the actual energy used by passenger cars is significantly higher because there are significantly more cars than buses or rapid transit trains. According to the DOT, there are 137,079,843 passenger cars (2008) in the U.S., which would require 183,933,000 TJ of energy over their lifetime, compared to the 850,530 buses and 1,576 eight car, rapid transit trains, each requiring 13,456,660 TJ and 949,474.9 TJ, respectively. Similar results are seen when calculation the total energy usage for all passengers (as opposed to all vehicles).
The UC Berkeley analysis appears to ignore the potential savings in fuel manufacturing and usage by alternative energy cars and buses (hybrids, hydraulic hybrids, etc.).
Bottom line, I disagree with O’Toole’s conclusions that the best way to make public transit more energy efficient is to privatize it (which would have the likely result of shifting more people into passenger cars and therefore increase the overall energy usage). But I do agree that increased ridership is really best source of both energy and emissions savings for mass transit, and perhaps the most difficult to achieve.