The San Francisco Municipal Railway (Muni) has ordered 56 Orion VII series hybrid diesel-electric buses, with an option for 56 more units. The order, the fourth-largest ever for hybrid buses, represent the first production hybrid diesel-electric units ordered by a major California transit system.
The Orion VII buses with the BAE HybriDrive combine a 5.9-liter, 260 hp (194 kW) Cummins ULSD (Ultra Low-Sulfur Diesel) engine with a 120 kW traction generator. The traction motor delivers 250 hp (186 kW) and 2,700 lb-ft (3,657 Nm) of low-end torque.
Regenerative braking recharges the lead acid batteries used for energy storage. The series hybrid design eliminates the transmission, removing a major maintenance item on vehicles operated in heavy stop-and-go conditions and eliminating the jarring shift points common among conventionally propelled buses.
Compared to conventional diesel propulsion, the hybrid units will provide 25%–35% better fuel economy. New York City transit reports average operational gains in fuel efficiency of 28% over conventional diesel buses, as well as over the GM-Allison parallel-hybrid diesel-electric buses in use in Seattle and other cities.
Emissions reductions are substantial: 90% less particulate matter, 40% less NOx, and 30% fewer greenhouse gases.
Orion will deliver the Orion VII model buses in 2006.
The hybrid purchases are part of Muni’s larger Zero Emissions 2020 Plan, which calls for the agency to establish an all-electric drive fleet that includes hybrid buses, battery buses, and fuel-cell buses by 2020.