The California Air Resources Board (CARB) recently eased rules for Bay Area transit districts replacing buses after 2007, and tightened restrictions on idling trucks beginning in 2008.
A CARB decision five years ago required transit operators to choose one of two paths to meet more stringent air quality standards—begin purchasing alternative fuel vehicles right away, primarily natural gas buses, or plan to buy cleaner diesel buses beginning in 2007 while doing pilot projects such as fuel cell vehicles. (See April/May 2005 issue).
Most Bay Area transit agencies chose the diesel path, and have continued to buy diesel vehicles which are cleaner than in the past but do not meet CARB's 2007 standard of 0.2 grams of nitrogen oxides (NOx). The federal standard is 1.2 grams until 2010, when it will drop to 0.2 grams. Diesel engine manufacturers expect to meet the 0.2 gram standard in 2010, but not by 2007.
Natural gas engines are expected to meet the 2007 standard and one option for CARB was to require all operators to switch to natural gas. The Metropolitan Transportation Commission calculated that this option would have cost Bay Area transit districts $270 million over the next 10 years for buses which may not perform well under Bay Area conditions.
Holding the 2007 standards as set would have meant that diesel path districts would be unable to replace buses between 2007 and the date when engines met the standard, probably in 2010. CARB's compromise solution was to keep the 2007 standard in place, but allow districts to purchase diesel engines which do not meet the 2007 standards if a one-to-one match is made with an older vehicle which is retrofitted with a new cleaner engine.
In a new addition to vehicle idling rules (see August/September 2005 issue), CARB applied the 5-minute limit on idling to drivers resting in a sleeper cab. Previously, the 5-minute rule did not apply when the driver was resting unless the truck was within 100 feet of a home or school. For many older vehicles, this will require the owner to add extra equipment. CARB estimates that 3 percent of onroad diesel use is by trucks idling to maintain temperature and equipment in sleeper cabs.
Leslie Stewart