Politics is full of premises that people take on faith without actually testing against facts. One such premise is that light rail investments reduce energy use and CO2 output. But data from the USDOT, as I posted before, shows that light rail at average occupancy and autos at average occupancy are in an energy dead heat. Driving a hybrid or even high fuel efficiency conventional automobile, even solo with no passengers, uses less energy and produces less CO2 per passenger-mile than light rail.
A group critical of the Denver light rail system brings us another data point. In their report (pdf), compiled from the official figures of the Denver transit authority, they claim: (via the Anti-Planner)
Denver's light-rail trains use 4,400 British thermal units (BTUs) and produce 0.78 pounds of CO2 per passenger mile. By comparison, the average SUV uses about 4,400 British thermal units (BTUs) and produces 0.69 pounds of CO2 per passenger mile.47 In other words, people who ride Denver's light rail when gasoline prices rise are not saving energy: they are merely imposing their energy costs on other taxpayers. If oil prices rise again, people can save more energy by buying more fuel-efficient cars than by riding energy intensive rail transit lines
Quite a while back, I made a light rail bet. I said that for the capital cost of constructing these systems, I could purchase every regular rider a Prius, and with the annual operating deficit each year could purchase gas for all these Prius's for a full year. This bet has not yet proved wrong (LA example), even for heavy rail (Albuquerque example). Now,though, in addition to being more cost effective, the hybrid is also more energy efficient.
Postscript: I am sometimes criticized for not including the highway construction cost in my Prius bet. First, a new highway lane has far more capacity than most light rail lines, and is far cheaper to build. I don't think anyone, even light rail supporters, dispute this. Light rail is generally supported over highways for what I would call aesthetic reasons -- light rail just strikes some people as more elegant a transportation solution. All the traffic carried by most light rail lines is generally a small fraction of a single highway lane. The congestion argument is a chimera, and is never supported, even in the fine print of transit authority statistics. From Denver's internal projections:
Now, RTD says the line will cost more than $600 million, which is a lot for a mere 11 route miles. Moreover, RTD has changed the proposed technology to something it calls "electric multiple-unit commuter rail," which sounds something like the Chicago Electroliners or some of the Philadelphia commuter trains.
For this high price, the DEIS reports incredibly trivial benefits. The proposed rail line is projected to take 0.0085 percent of cars off the road. Of course, that's for the region as a whole, but in the corridor it will take a whopping 0.227 percent of cars off the road. A handful of buses could do as well.