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In Spring 2003, Max Nofziger ran for mayor of Austin, and part of his transportation platform was to replace the city's diesel buses with ones that run on natural gas. Below is Dave Dobbs' argument that natural gas buses may be no better than diesel buses.
As both a bus user and a transit researcher who has examined the pros and cons of natural gas buses, I can tell you they are far from the "clean machines" that Max would have you believe. Like everything else, there are trade-offs.
Max's idea that replacing Capital Metro's nearly brand-new fleet with 400 natural gas buses will somehow magically improve Austin's air quality not only fails the smell test, it has a number of implicit assumptions that aren't so. Among them are:
(1) "Bus exhaust is a major factor in Austin air quality."
(a) In fact, Cap Met bus daily VMT is something less than 150 k a day including the UT shuttle while automobile VMT for the region is somewhere around 2.7 million. Mostly these are SOVs (single occupancy vehicles). Pollutants per passenger mile on buses is miniscule compared to the amount produced by cars using the same measure.
(2) "Natural gas buses (CNG) is cleaner than diesel"
(a) In fact, CNG and diesel bus engines both easily meet federal air quality standards.
(3) "Other than being more expensive to buy, a CNG bus is (a) either cheaper to operate or (b) about the same as a diesel bus and is really just a bus, but cleaner."
(a) In fact, nominally CNG buses cost about $300--$325 k (each) while conventional diesels cost about $250 k--$275k.
Far from being better, CNG is more problematic and less reliable. Note that Detroit Diesel (now part of Daimler Chrysler), the primary builder of both CNG and diesel bus engines, gives extended warranties on diesel engines but does not do so with its CNG engines.
And for the record, Capital Metro's maintenance department is the winner of numerous commendations for its efficiency and quality of service in all kinds of vehicle engines including CNG power plants.
Reliability and least-cost-per-passenger-mile are two important keys to making public transit an alternative to driving from whence most of Austin's air quality problems stem. Converting our bus fleet to CNG at this point in the technology is neither cost-effective nor commensurate with Austin air quality goals. Bicycles are and reliable buses are cost-effective and commensurate with these goals, but until we are more than a bus system, everyone, including the driving public is going to find the situation increasingly untenable.
Like so many politicians in the last 17 years, Max is just the latest in a long list trying to hijack a Cap Met bus into office and after mugging the driver and diverting the bus, screaming that it didn't run on time.
I love politics!
--Dave Dobbs, May 2, 2003