Yesterday, we found that light-rail systems in Houston, Minneapolis, Portland, Salt Lake City, San Diego, and St. Louis seemed to be energy efficient compared with automobiles. But are they really?
When transit agencies open light-rail lines, they don’t usually make significant reductions in bus service. Instead, they convert corridor bus lines to feeder buses for the light rail. Since many people end up driving to light-rail stations, these feeder buses end up carrying far fewer riders than the corridor buses that the light-rail replaced.
Thus, rail transit’s energy and CO2 cost per passenger mile savings are potentially offset by increased energy and CO2 costs per bus passenger mile. I first noticed this for Salt Lake City. The Utah Transit Authority brags about the great success of its light rail, and it did lead to a modest increase in total transit ridership (although ridership was growing even before it opened the line).
When it opened the light-rail line, Utah Transit actually increased miles of bus service. Yet the average load of Utah Transit’s buses fell by almost half, from 8.9 to 4.5 riders. As a result, the BTUs per bus passenger mile more than doubled. While light rail consumes only about 2,700 BTUs per passenger mile, the average for the transit system as a whole increased from under 4,300 in 1992 to nearly 5,600 in 2005. Greenhouse gas emissions increased from 0.69 to 0.91 pounds per mile, both well over the emissions from the average car (3,445 BTUs and 0.54 pounds of CO2 per passenger mile).
Let’s take a look at the other cities that seem to have energy-efficient light-rail systems. In most cases, I will compare the year before a light-rail line opened with the year after. In a few cases, I compare two or three years before the line opened with the year after because rail construction often leads to disruptions in bus service and ridership losses that would not have taken place without the rail project.
Houston: In 2001, Houston’s bus system required 3,680 BTUs and emitted 0.59 pounds of CO2 per passenger mile. Houston opened its light-rail line in 2004, and in 2005 the region’s transit system consumed almost 4,000 BTUs and released 0.65 pounds of CO2 per passenger mile.
Minneapolis: Before opening the Hiawatha light-rail line in 2004, the Twin Cities’ transit system was using about 4,000 BTUs and emitted about 0.65 pounds of CO2 per passenger mile. The light rail improved the system-wide average to 3,875 BTUs and 0.55 pounds of CO2 per passenger mile. Note, however, that this is still not quite as good as an average car.
Portland: Portland’s transit system has two major lines with two minor branches. Before the first line to Gresham opened in 1986, the region’s bus system was using 3,700 BTUs and releasing 0.60 pounds of CO2 per passenger mile. After the line opened, energy consumption increased to 3,900 BTUs and CO2 emissions increased to 0.68 pounds per passenger mile.
Between 1988 and 1998, Portland’s transit ridership grew by 54 percent, which sounds impressive unless you know that during the 1970s bus ridership grew by 150 percent. So the system was much more efficient when the second light-rail line opened in 1998, consuming just 3,260 BTUs and emitting just 0.54 pounds of CO2 per passenger mile — about the same as an automobile. This wasn’t solely because of light rail: at 3,500 BTUs per passenger mile, Portland buses alone were doing much better in 1998 than they were in 1983 or 1988.
Portland lost ground again when it opened a new light-rail line to Hillsboro. In 2000, the first full year of operation of that line, energy requirements increased to 3,500 BTUs and CO2 emissions grew to 0.60 pounds per passenger mile.
Portland opened a 5.5-mile branch in 2001 and a 5.8-mile branch line in 2004. The overall transit system’s energy consumption improved after each opening, but the biggest improvements were due to increased bus ridership, which boosted bus efficiencies from 4,100 BTUs to 3,600 BTUs between 2000 and 2002 and from 3,640 to 3,360 BTUs per passenger mile between 2003 and 2005. Light-rail energy costs declined from 2,500 to 2,200 BTUs per passenger mile between 2000 and 2002, but increased from 2,040 to 2,200 BTUs per passenger mile between 2003 and 2005. These two branch lines are so short and lightly used that the changes in energy use may have nothing to do with them.
San Diego opened the first modern light-rail line in the nation in 1981, but my data don’t go back that far. So let’s look before and after 1999, when San Diego added a new line that doubled the total number of miles of light-rail service.
Before the line opened, San Diego transit was using about 3,300 BTUs and releasing about 0.62 pounds of CO2 per passenger mile. The new light-rail line improved things slightly, reducing energy use to 3,000 BTUs and CO2 emissions to 0.59 pounds per passenger mile.
St. Louis‘s light-rail line has been heralded as a great success, and it did for a time seem to turn around a transit system that had been steadily losing ridership. Before the first line opened in 1994, the region’s bus system had been using about 4,600 BTUs and emitting 0.75 pounds of CO2 per passenger mile.
In 1995, the first full year of light-rail operation, total ridership dramatically increased. But bus ridership significantly dropped even though the agency increased the vehicle miles of bus service. The result was that energy consumption increased to more than 5,200 BTUs while CO2 emissions grew to 0.88 pounds per passenger mile.
A thriving economy led to increases in both bus and rail ridership over the next five years. In 2001 St. Louis opened a second light-rail line. Again, bus ridership plummeted, while rail passenger miles grew. BTUs per passenger mile increased for both bus and rail, but paradoxically, the system as a whole reduced energy consumption by about 2 percent per passenger mile. This happened because many former bus riders started using the new rail line. CO2 production per passenger mile remained constant.
Heavy rail: Yesterday’s analysis noted that new heavy-rail lines in Atlanta, San Francisco-Oakland, and Washington seemed to save energy while lines in Baltimore, Los Angeles, and Miami did not. Existing heavy-rail lines in Boston, Chicago, Cleveland, and Philadelphia also do poorly compared with autos; of existing heavy-rail systems, only New York’s (and not all of the ones in New York) compares favorably with cars.
The BART line to Dublin cost a lot and carries relatively few passengers.
Flickr photo by Velo Steve.
The Atlanta, San Francisco-Oakland, and Washington lines also started before the earliest data I have available (1982). BART, which seems to be the most efficient of the three, opened a large addition to Dublin in 1997. This branch serves Contra Costa and Alameda counties, so we can compare just the Contra Costa and Alameda bus systems with BART. In 1996, before the Dublin line opened, these three systems used 2,935 BTUs per passenger mile. After the line opened, energy consumption increased to just over 3,100 BTUs per passenger mile. Total passenger miles increased by less than one percent, so the benefits of getting a few people out of their cars were more than made up for by the loss of efficiency for the 99 percent who were already riding transit.
In sum, Houston, Portland, Salt Lake, and St. Louis’s first light-rail line all led to significant increases in energy usage. Minneapolis saved some energy, while San Diego and St. Louis’s second line both saved slight amounts of energy. Except in places like inner New York City, heavy rail is not a great energy saver either.
Considering the high energy costs of building rail lines — a subject for tomorrow’s post — it does not seem worth building rail transit to obtain a small energy savings, and certainly not worth it if energy requirements go up.
