RAISING THE BAR FOR DIESEL EMISSION STANDARDS

Tough clean air standards for diesel engines for 2004 and 2007 will force manufacturers to add new technologies, which will require more sophisticated maintenance by transit operators. The EPA expects to get the equivalent reduction of removing 90% of pollution from today's diesel buses and trucks. Exhaust gas recirculation (EGR) is the main tool for cutting down NOx, but it creates extra engine heat, and cooling methods can reduce fuel efficiency or add to maintenance costs. Cummins' ISX model got certification on the 2004 standards, with Detroit Diesel saying it was not far behind. To meet California's stricter requirements will in effect bring them into compliance with 2007 EPA rules, using particulate filters. They need ultra-low sulfur fuel to operate properly. Some transit agencies are investigating diesel alternatives such as compressed natural gas and hybrid electrics.