In 2004, Seattle became the first city to put GM hybrid transit buses into service.
photo: General Motors
Passenger cars with hybrid gas-electric drive systems have been generating a tremendous amount of publicity lately, due to the technology's fuel savings and reduced emissions. Sales of hybrid passenger vehicles remain strong, with demand still growing. Amid this increasing interest comes a new product from General Motors that will put hybrid technology beneath even more people: hybrid transit buses.
As part of its wide range of fuel-efficient advanced technologies, General Motors has developed a commercial parallel hybrid system that combines a diesel engine with electric motors to power transit buses.
On May 27th, 2004, at Seahawks Stadium in Seattle, GM officially delivered the first of 235 hybrid buses—the largest order to date—to Metro Transit of King County, Washington. Metro Transit ordered 213 hybrid buses and Sound Transit Regional Express ordered 22 more.
The first buses were put into service on June 5, 2004, with all 235 buses destined for King County expected to be in service by the end of the year.
Improved Fuel Economy, Lower Emissions
The hybrid buses delivered to King County are 60-foot-long articulated units assembled by New Flyer of Winnipeg, powered by the Allison Electric Drive system utilizing technology developed by GM's Powertrain division.
The hybrid system combines an 8.9-liter Caterpillar diesel engine with two 100 kW electric motors, and can deliver up to 60 percent better fuel economy than a traditional diesel bus. The GM hybrid buses produce much lower hydrocarbon and carbon monoxide emissions than conventional diesel-powered buses. In addition, particulate emissions (tiny pieces of soot and dust) are lowered by 90 percent and nitrogen oxide (NOX) emissions are lowered by up to 50 percent.
The 235 hybrid buses that operate in the Seattle area are expected to save 750,000 gallons of fuel per year over the buses they will replace. Over the 12-year life cycle of the vehicles, the total savings is expected to be 8 million gallons of fuel.
If America's nine largest cities replaced their transit fleets—totaling 13,000 buses—with GM's hybrid buses, GM states the cities would save 40 million gallons of fuel each year—a greater savings than 500,000 small hybrid vehicles.
"This bus employs the most efficient hybrid architecture available in the world today, and is the first step in a larger GM initiative," said Tom Stephens, group vice president of GM Powertrain. "You get low emissions, great fuel economy, smooth and quiet operation, but one other thing is acceleration," explained Stephens. "You look at 60-foot buses like this and you know how slow they typically are, but with this system the buses are 50 percent faster for acceleration than a conventional bus, so all in all it's just a tremendous balance of values for the consumers."
Another advantage of hybrid technology is a regenerative braking system, which captures and stores braking energy. "When you get into a hybrid system like this . . . every time you brake to a stop you convert that braking energy into electricity and store it in the battery, so the next time you accelerate you can use that braking energy to accelerate the bus," explained Stephens.
Lower Maintenance Costs, Quiet Operation
In addition to the fuel savings and emissions improvements, the GM Hybrid Transit Bus has operational sound levels equivalent to passenger cars. Metro Transit also expects the new buses will result in significant savings in maintenance costs.
Jim Boon, vehicle maintenance manager for Metro Transit Division of King County, told MSN Autos that they have not made any operational compromises nor any changes to the infrastructure to accommodate the new hybrid buses. "This bus just walks on and goes to work," said Boon, who expects to be able to extend oil-change intervals in the hybrid units, saving up to 32,000 quarts of oil per year, plus labor and disposal costs.
"The sound level of this bus in hush mode is about equivalent to a regular passenger car," said Stephens.
In a conventional bus, when you go to drive away you hear the diesel engine rev up and you get the noise and vibration, then you feel a strong jerk when it shifts into second gear.
"This bus is totally different," explained Stephens. "When you go to drive away you hear next to nothing. The electric drive system augments the torque required to drive away and helps the diesel engine so you get a nice, smooth, quiet drive away and there are no shifts whatsoever; it is totally smooth, more like light-rail transportation as opposed to what you conventionally think of with bus transportation."
GM says that the hybrid system being used in the hybrid transit buses today will be scaled and transferred in full-size sport-utility vehicles and full-size pickup truck in the next few years. "These buses are incredibly significant for us," explained King County Executive Ron Sims, "We wanted a 21st century bus with lower operation and maintenance costs that wouldn't be dependent solely on petroleum-based products. We wanted a bus that would literally improve our air quality in a very significant way, and we wanted a bus that is a complete technology."
"The public wants clean air and public transportation is a key component of that," Sims concluded.
GM "Road to Hydrogen" Tech Tour
In addition to the press conference officially delivering the first GM Hybrid Transit Buses to King County, the GM "Road to Hydrogen" Tech Tour made a stop in Seattle to showcase other emerging fuel-efficient technologies.
The tour included current and near-term technologies such as gas-electric hybrids; cylinder deactivation, known as Displacement on Demand; alternative fuel vehicles; and clean diesels.
The first production gas-electric hybrid full-size pickup was on display and available to drive. A Chevrolet Silverado Extended Cab, the first of 50 hybrid pickups, was delivered to Miami-Dade County in May. The trucks will be available to the public in the fall of 2004.
The hybrid system combines the 5.3-liter 5300 Vortec V8 engine with an electric motor integrated into the transmission housing. The technology makes the truck more efficient in stop-and-go traffic by shutting off the engine at idle mode, and allowing early fuel cutoff during deceleration for an improvement in fuel economy between 10 and 12 percent.
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