Many Seattleites assume public transportation is vastly more energy efficient than cars, and that spending more money on transit will attract people out of their cars. In 1979, University of California at Irvine economist Charles Lave showed in The Atlantic Monthly that both of these assumptions were wrong. Persuading people to buy more fuel-efficient cars is easier and saves more energy, Lave found, than trying to get them to ride transit.
Today, transit advocates argue we need to spend more money on transit, and in particular, rail transit, to reduce greenhouse-gas emissions as well as save energy. Yet, Lave's points are more valid than ever.
Driven by higher gas prices, America's auto fleet today is almost 40 percent more fuel-efficient than in 1979. In contrast, the energy efficiency of both bus and rail transit has declined as transit has reached into distant suburbs where few people use it. Despite investing hundreds of billions of dollars in transit improvements, the share of urban travel served by transit has actually declined from just under 3 percent in 1979 to well under 2 percent today.
Buses today consume as much energy and emit more greenhouse gases, per passenger mile, than the average SUV. Most light-rail systems also consume as much as or more energy per passenger mile than SUVs, and 40 percent emit more greenhouse gases per passenger mile than the average car.
Moreover, even where rail operations do save energy, this savings hardly ever makes up for the huge energy cost of rail construction. Metro, Portland's regional planning agency, estimated that the area's North Interstate light-rail line would require 172 years of operational savings to make up for the energy cost of construction. Highway construction also consumes energy, but because highways are more heavily used than rail lines, their energy cost per passenger mile is far lower.
If we ignore construction costs, many rail operations do consume less energy than the average auto — but almost none consume less than a Toyota Prius. As Lave suggested in 1979, to save energy and reduce greenhouse gas emissions, it is far more cost-effective to encourage people to drive more-fuel-efficient cars than to build rail-transit lines.
Transit agencies that want to save energy and reduce greenhouse-gas emissions should focus on increasing bus loads or reducing the size of their buses. The average King County Metro bus has 44 seats, yet carries on average just 14 passengers. Concentrating service in areas where loads are higher, and using smaller buses in areas or at times of day where loads are lower, will do far more to save energy than building rail transit.
Transit agencies could also consider alternative fuels. Hybrid-electric buses, for example, save far more energy per dollar invested than the most efficient rail systems.
Seattle's light-rail operation will generate less greenhouse gases than diesel buses because it will be powered by hydro and other renewable sources of energy. But Seattle could save even more by expanding its electric-powered trolley buses, which are far less expensive to build — in both dollars and energy — than rail transit.
Cities that really want to save energy should focus on the form of transport people use most: automobiles. As Lave noted, "the biggest components matter most," so improving the mode that moves 95 percent of people will do far more than the mode that moves only 2 percent of people.
The most important thing cities can do is relieve congestion. The Texas Transportation Institute estimates urban congestion wastes nearly 3 billion gallons of fuel each year, in turn emitting 28 million tons of CO2. This has more than quintupled since 1982.
One simple way to relieve congestion is to coordinate traffic signals. The Federal Highway Administration estimates that three out of four traffic signals need updated coordination systems. Signal coordination costs little yet can save huge amounts of time, fuel and emissions.
Another way to relieve congestion is to build new roads and pay for those roads with tolls that vary by the amount of traffic on the roads. Variable tolls can keep roads free-flowing at all times, saving both energy and greenhouse gases.
There may be places in the world where rail transit works. There may be reasons to build it somewhere in the U.S. But saving energy and reducing greenhouse-gas emissions are not among those reasons. Washington cities that want to be green should look to other strategies that are far more cost-effective than investing in high-cost rail systems.