Hybrid buses are vital to the Link light rail system. The hybrid diesel-electric technology enables both trains and buses to use the Downtown Seattle Transit Tunnel.
Hybrid electric technology is becoming increasingly popular in the transit industry as agencies seek more environmentally friendly and cost-effective propulsion systems. The reported benefits of this advanced transit vehicle powertrain are improvements of 25 percent or more in fuel economy, a reduction in emissions by 60 percent to 90 percent, a reduction of one-third the brake wear, and better acceleration resulting in a smoother ride.
In addition, the buses are engineered with a “tunnel mode” where power largely comes from batteries, with the engine idling only when needed to keep the batteries charged. This will allow the buses to run on battery power when they are operating in the tunnel.
The onboard diesel engines are equipped with a low emission fuel management system, which includes exhaust particulate filters to virtually eliminate particulate matter, carbon monoxide, and hydrocarbon.

Quick information about the ST Express New Flyer 40-foot Diesel-Hybrid Bus
|
Length |
40 feet |
|
Height |
11 feet |
|
Weight |
30,800 pounds |
|
Width |
8.5 feet |
|
Passenger capacity |
Seating for 37 passengers |
|
Fuel type |
Clean diesel, biodiesel and electricity |
|
Fuel capacity |
112 US gallons |
|
Power |
Cummins ISL |
|
Year of manufacture |
2003 |
|
Number of vehicles in fleet |
1 |
|
Cost per vehicle, inclusive |
$617,443.59 |
Additional information:
Manufacturer and assembly of the bus
This bus is manufactured by New Flyer, and the hybrid manufacturer is Allison Electric Drive.
2003.
No modifications.
The hybrid bus was tested for approximately 18 months in a variety of traffic and driving conditions. It rotated through the region’s transit agencies and will run on their regular service routes, both local and express. Ultimately, the hybrid bus was evaluated for its operating system, fuel consumption, operational feasibility, customer and driver acceptance and emission level reductions.
The Puget Sound Clean Air Agency assisted in the evaluation of the air quality data.
The demonstration testing gave the region a good picture of the capabilities of the bus for potential future purchases.
The bus uses both electricity and diesel – the same concept as hybrid automobiles. When it operates in the Downtown Seattle Transit Tunnel, it will use its batteries. This will reduce emissions within the tunnel. On the surface, the bus is powered by either diesel or battery-stored electricity.
Fuel consumption is reduced up to 30-40 percent, due to the unique combination of diesel and electricity.
In addition, exhaust emissions are as clean as natural gas-powered vehicles. Pollutants that can cause smog, greenhouse gases, and other irritants are greatly reduced.
Overall emissions are cut by 90 percent over standard diesel buses, particulate matter is decreased by 90 percent, carbon monoxide is cut by 90 percent, hydrocarbon is reduced by 90 percent, carbon dioxide is reduced by 40-60 percent, nitrogen oxide is cut in half and the diesel exhaust odor is eliminated.
How the bus fits in with Sound Transit’s fleet
Sound Transit bought one 40-foot diesel-electric hybrid and managed the coordination of a demonstration project with its regional transit partners. The bus rotated in three-month intervals with each participating agency. At the end of the demonstration period, it was evident that the seating capacity would not work for the type of commuter service Sound Transit provides. As a result, Sound Transit will not purchase more.
Electricity is stored in onboard batteries and is generated through a combination of braking, deceleration and a diesel engine. The stored electricity is used for a cleaner and smoother propulsion. The two power sources, electricity and diesel, are balanced so the most efficient source is always used.
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A quiet ride
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American with Disabilities Act-approved wheelchair ramp and two wheelchair positions on board
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Air conditioning
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Overhead racks
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Reading lamps
The bus is assigned to King County Metro Transit's South Base for operations and maintenance.











