To some, mass transit seems like a good way to conserve energy and fossil fuels. A few writers have argued that properly engineered mass-transit lines would be more energy efficient than even hybrid vehicles.

There have been numerous studies about the realities of mass transit. With gasoline on its way toward $5 per gallon, perhaps it is time to review some of them.

The bad news is that installing new mass-transit lines doesn’t attract many riders. According to a University of California (Irvine) study, no U.S. region has been able to coax more than about 1% of commuters to switch from car travel to rail, for example. The same dynamics that make many rail lines expensive boondoggles would tend to work against any people-moving scheme. This becomes clear when you analyze the few parts of the country in which rail transit does indeed make economic sense.

In Manhattan, for example, most people take a train or bus to work. The reason has nothing to do with well-engineered rail lines but everything to do with population and job density. Manhattan is over 20 times more densely populated than most urban areas. Even more important, there are over 2.5 million jobs to be found within the few square miles of the island. Small wonder, then, that New York City is the only U.S. metro area where bus or rail carries more than 15% of commuters to work.

Contrast New York City with the situation in typical urban areas. No more than 40% of jobs reside downtown or in suburban centers, according to a recent study by economist William T. Bogart. That means any transit system focused on gett ing people into a city will serve well under half the commuters in the surrounding area.

For similar reasons, most people won’t regularly use mass transit for shopping. Economists point out that consumers keep costs low by going to wherever they get the best deal, not just to stores near transit lines. In fact buyers tied to mass transit, such as the poor, are stuck patronizing only merchants close to transit stops and often end up paying higher prices.

It’s not like municipalities save money by installing rail lines instead of more roads. A mile of light-rail transit line typically costs more to build than a mile of four-lane freeway. Heavy rail like San Francisco’s BART or Washington, D.C.’s Metro costs even more.

There have been a few recent press reports of people moving near mass-transit stations to get relief from gas prices. But at least in the stories I’ve seen, these new city dwellers are either golden-agers tired of mowing lawns, or childless 20-somethings. Most consumer surveys continue to show the majority of people prefer to live in a house with a yard. So it is probably unrealistic to expect a mass migration downtown.

But here’s a counterintuitive way to save energy and go easier on the environment: Build more freeways. The Texas Transportation Institute calculates that traffic congestion forces individual drivers to waste 2.9 billion gallons of fuel annually and add 28 billion tons of CO2 to the atmosphere. Those figures would be even higher if the costs to businesses were factored in.

— Leland Teschler, Editor