Myth: The Efficiency of Public Transportation

by

In the 1970s, public transportation was publicized as a source of efficiency during a time of substantial energy shortages. With cars achieving an average of 13 miles per gallon at the time, this was an accurate assessment—but things have changed.

When you’re on your way to work and find yourself on a packed city bus standing shoulder to shoulder with your fellow commuters, hoping in vain to get lucky enough to squeeze into one of those luxurious hard plastic seats--its hard to imagine that public transportation isn’t energy efficient.

And while that particular bus at that moment definitely is, mass transit on the whole is not. That bus had to begin its journey somewhere, and when it did, it was likely quite empty. Next, the bus has to head back against the flow of rush hour with a fraction of the riders. Add to that all of the off-hours trips it will take throughout the day and you end up with a bus that is largely empty most of the time.

Misconceptions: Because there’s no one around, few people experience next-to-empty mass transit vehicles, but they run on a regular basis.

This phenomenon exists throughout the varying types of public transportation, and leads to the figures below. Here are the average occupancy rates in common forms of public transportation:

Bus

15%

Light Rail

14%

Heavy Rail

17%

Commuter Rail     

21%

 These levels of one-fifth occupancy or less lead to interesting results when the efficiency of these systems is compared to the traditional automobile. Here are some figures based on BTUs per passenger mile, across different fuel types:

Automobile

3,500

Bus

4,300

Light Rail

3,400

Heavy/Commuter Rail     

2,600

 So in terms of energy efficiency, a bus is worse and light rail is comparable to just driving your car.  And although subways and commuter rail systems are 25% better, they are limited to the relatively few metropolitan areas that can afford them.