Wednesday, November 18, 2009

Public Transportation Paradox

Recently, more and more daily commuters have been going green by using public transportation. Mass transit is viewed as highly efficient, and a step in the right direction. There is a variety of positive aspects of mass transit besides energy efficiency. The most important aspect of mass transit is that it provides very cheap transportation for those who cannot afford to drive or are able to drive. It also helps reduce congestion at rush hour as well as parking congestion. Mass transit is also much safer, producing fewer accidents and injuries than cars. There is also the social aspect of mass transit that people tend to overlook. Public transportation almost forces someone to step out of their "inverted quarantines" and actually interact with others in the community. Seeing familiar faces on a bus or train builds up the sense of community, rather than looking at yourself in your rear-view mirror.

Unfortunately, mass transit is not as efficient as many may think. Brad Templeton, a private researcher who interviewed both the Department of Energy and the Department of Transportation stated that: "I was disturbed to learn that city diesel buses and electric trolley buses are both mildly worse than the car in energy efficiency." How can this be, you ask. When viewed at logically, a paradox presents itself.

A full busload or trainload of people is much more efficient than private cars. But that same bus or train is not ALWAYS full. That bus or train is only filled to capacity at specific times of the day, like rush hour or lunch hour. Also, when that full bus or train reaches its destination, it unloads and then must return empty back to the original stop. Another aspect of the paradox is the design of these mass transit vehicles. A bus tends to start and stop frequently, which consumes a lot of energy. Now imagine that same bus filled to capacity starting and stopping frequently. Much more energy is consumed. Another aspect of the paradox is the lack of progress of design for these mass transit vehicles. Brad Templeton reports that "Over the past 30 years, private cars have gotten 30% more efficient, while buses have gotten 60% less efficient and trains about 25% worse." So, as buses and trains get less aerodynamic, they become less efficient.

Although this slight paradox makes public transportation seem less green, in the end it is in fact more efficient than driving. It is believed to be much more efficient for an individual to take already existing mass transit than their car. Since the transit is already running, adding one more individual to the transit is more energy efficient than driving individually.

No comments:

Post a Comment