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SF Muni Orders 56 Orion Series-Hybrid Diesel Buses

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 models are the same as used by NYC Transit (earlier post and Toronto Transit (earlier post)

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.




Do we know:

* the sticker price differential between the hybrid diesel and conventional diesel?
* the expected maintainance costs per year differential between the two?
* the expected fuel costs per year differential between the two?

In other words, is this purchase financially responsible when not considering the environmental or political responsibilities at all? When is the break even point?

Joseph Willemssen

"In other words, is this purchase financially responsible"

Are you a San Francisco taxpayer?


The 56 coaches carry a “list price” of $550,000 each.

With purchases for spares, training, manuals, etc, that increases to a total of $41,124,493 for all 56, or $734,365.95 per bus.

Another $9 million is being allocated for support services for the project, and an additional $1,483,352 for a design phase. Total project cost = $51,685,783...or $922,960.41 per bus.

Proposition K funding is providing 47% of the total, with the remainder coming from federal funds and bridge tolls.

(Details in Muni Hybrid Bus Allocation Memo here.)

New York City Transit has the largest fleet of Orion VIIs extant, and they’ve been seeing fuel economy savings of up to 35% to 40%. Looked at another way, they say they’re saving about 5,000 gallons of diesel per year per bus. So, say approximately $13,000 savings per year on fuel per bus, at current prices.

According to NYCT, the differential cost per bus (just the rolling stock cost, not support, training, and so on) is $125K–$200K.

On a projected 12-year bus life (which is low), the fuel cost differential—assuming that diesel prices do not continue to rise—would be some $156,000 per bus.

On the maintenance side, brake maintenance is lower, but then there are maintenance issues with the electric components. Again turning to New York’s operational experience, the hybrid fleet has been operating at above the NYCT fleet availability target of 85%. I don’t have hard figures on reduction or increase in maintenance cost.

All that said, doing a straight cost justification for hybrid buses on the basis of fuel cost has been, at least until recently, not viable alone for making the transition. But factor that together with the significant emissions reductions, and the picture begins to change.


It's been my experience with public transit that every new bus has gone through about a 6 month period of excessive down time due to construction errors. NYC's experience with series hybrids shows that the hybrid drivetrain is inherently more reliable than the traditional drivetrains.

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