Comparing the average emissions per passenger mile ofvarious transport modes. (Chart: FTA)
While state DOTs marked Earth Day by
depicting roads as unsung heroes of livability, the Federal Transit
Administration (FTA) and the transit industry celebrated in their own
ways by releasing reports on local rail and bus systems' roles in
reducing U.S. transport emissions.
The FTA's updated report [PDF]
on transit's value in combating climate change includes average
emissions for various modes of transportation (see above chart),
calculated using the government's National Transit Database.
The emissions totals, which reflect average ridership estimates, show
that transit averages about half the CO2 poundage per passenger mile of a
single-occupancy vehicle.
But the FTA also breaks down individual transit systems' average
emissions, illustrating how much of a difference high ridership -- and
cleaner-burning sources of electricity -- can make when it comes to the
energy efficiency of local rail.
Take the San Francisco metro area's heavy rail system, known as
BART, which achieves average emissions of just 0.085 pounds of CO2 per
passenger mile. That rock-bottom total is made possible by electricity
generated largely through hydropower. Washington D.C.'s Metrorail,
meanwhile, comes in at an average of 0.347 pounds of CO2, making it four
times less efficient than BART.
The emissions numbers get worse in less trafficked rail networks,
such as the Baltimore Metro (0.919 pounds of CO2 per passenger mile, an
average comparable to a car) and Cleveland's rapid rail transit (0.805
pounds of CO2/passenger mile).
Fortunately, the average emissions-cutting power of heavy rail is
skewed by New York City, where nearly 60 percent of the mode's U.S.
passenger miles are traveled. New York's subway gets an average of 0.147
pounds of CO2 per passenger mile, bolstering the local transit
authority's new
estimate that it saves 17.4 million metric tons of emissions every
year.
The FTA report found similar variability in the average emissions
of local light rail, which ranged from uber-efficient in Los Angeles
(0.219 pounds of CO2/passenger mile) and San Francisco (0.299 pounds of
CO2/passenger mile) to middling in Dallas (0.534 pounds of CO2/passenger
mile) and higher than the average single-occupancy auto in Pittsburgh
(1.371 pounds of CO2/passenger mile). The weighted average for all
American light rail, however, came in at 0.36 pounds of CO2 per
passenger mile.
On the transit industry's end, Earth Day brought a statement of
support from President Obama that was echoed by American Public
Transportation Association (APTA) chief William Millar. "Everyone who
cares about the environment should care about public transportation,"
Millar said in a statement that accompanied a lengthy list of
efficiency improvements underway at transit agencies across the country.
