With more than 24 million revenue miles on hybrid buses, I thought this might be a good time to step back and reflect on what this new propulsion system is doing to the way we think about a transit bus.

Throughout the North American transit industry, operators are embracing this new way of looking at the transit bus. Several operators, however, remain in the wait-and-see mode, not wanting to be first with new technology. It is safe to say that the wait for new propulsion technology is over. Hybrid is real; hybrid is rock-solid technology; hybrid is reliable, efficient, economically viable and environmentally prudent. The paradigm shift is clear with more than 1,000 vehicles operating across North America.

Hybrid technology has provided the transit industry with new opportunities for efficiency and new operating economies. Hybrid propulsion has the unique ability to blend power, giving smoother acceleration and deceleration. Gone are the rough shifts of automatic transmissions. Transit operators benefit from this in two important ways: improved customer comfort and longer life for the power components.

Hybrids have also allowed bus builders and operators to look at engines differently. Operators can now foresee engines that will run the life of the bus without overhaul. Did you ever think in your lifetime this would be a reality that you could depend on, or even go so far as to build an operating budget around such an assumption? Hybrid propulsion brings that opportunity.

Maintaining road speed doesn’t take all that much horsepower. Launching the vehicle from a stop, however, can take up to 60 percent of the available horsepower and that action is the beginning of thermal dynamic activities in the engine that typically cause accelerated component wear and rapid degradation of oil. Hybrid propulsion uses electric motors to do this ”heavy work” while only generating a fraction of the heat. The reduction of heat here provides the same rewards as it does for the engine. The power-train components will last the life of the bus.

When hybrid propulsion came to our market, the transit bus engine found a new friend, the energy storage system. The energy storage system, or battery pack, shaves off the peak power demands for the engine. The engine, working in concert with battery energy reduces the traditional need for higher horsepower and reduces the thermal dynamic loads on the engine. Engines, running at a more constant temperature, will last a very — very long time.

If an operator wants to build-in a little more insurance, stay with a slightly larger size engine, and more horsepower. This will provide a more robust engine carcass but allow it to operate at an even lower load factor, thus providing even longer life.