The deployment of hybrid-electric buses into transit operation brings with it a series of maintenance and training challenges. New York City Transit (NYCT) has been ahead of the curve on this front, and John Walsh, the chief maintenance officer for the agency's department of buses, has been heavily involved in the hybrid-electric vehicle (HEV) program from its inception about five years ago.
To get a fix on how the program is developing, METRO Editor Steve Hirano posed several questions to Walsh, who, incredibly, found time in the middle of the Republican National Convention to hammer out the following answers.
NYCT has been running hybrid-electric buses since 1999. Have they performed up to expectation?
John Walsh: The deployment of any new immature technology is never without challengers. This certainly has been the case with HEV technology. Our objectives were to develop and iteratively improve the technology with the pilot fleet of 10 Orion VI buses with the first-generation BAE system. Our expectations were achieved.
Vehicle performance Acceleration, driveability and operator acceptance are equal to or better than buses with standard propulsion systems.
Emissions We were very pleased at the overall emission signature of the buses. A great deal of comparative testing was done between competing low-emission technologies. The hybrid results were excellent.
Vehicle noise Both the external and internal noise signatures from buses have been a concern of customers for some time. The power management and energy delivery of the hybrid bus has given us surprisingly good results.
Battery life We were very concerned about the reliability and service life of the energy-storage system on the hybrid buses. The performance to date has certainly been encouraging. However, as with other alternatively fueled vehicles, the energy storage adds significant weight to the bus. This is certainly one of the challenges for the future.
The overall system reliability has improved as a result of what we learned with the pilot fleet. Those improvements have been integrated into the production HEV systems and MDBF [mean distance between failure] has improved to the point where it is comparable to diesel buses. That has been a much-needed success.
The production HEV buses have been showing very impressive improvements in fuel economy. The fuel economy is 30% to 40% improved over the buses they are replacing. This is certainly better than we anticipated.
How many do you currently have in operation?
The rate of new bus deliveries from Orion has increased significantly in recent months. We have 51 buses in service with a total mileage of over 250,000 miles. They are currently assigned to one location in Manhattan (Mother Clara Hale Depot) and one in Queens (Queens Village Depot).
What's been the biggest maintenance challenge with these vehicles?
All new vehicles are a maintenance challenge. The skill set needed to diagnose and repair microprocessor-controlled systems has added complexity to the maintenance function. That, however, is a universal condition.
If you look strictly at the HEV buses, managing batteries and high-voltage systems is a unique challenge. But, it is important to note that the hybrid buses are equipped with very powerful diagnostic tools that have become a very important part of improving the efficiency of repairs.
How different is the preventive maintenance program (PM) for a hybrid vehicle vs. a standard diesel bus?
Our PM programs are driven by the vehicles' duty cycle and the vocation of the vehicle. The only items that are unique to the hybrid are battery conditioning, high-voltage connection and wiring integrity checks, and a segregated cooling system for the PLC. The tasks are integrated into our normal PM programs, as they would be for CNG or clean diesel specific PM tasks.
Longer term, our internal component overhaul capabilities will have to add more traction motors and fewer transmissions, but overall nothing of great significance.
Based on your experience with the hybrids, are you optimistic about their future?
I am very optimistic about the future of hybrids for a number of reasons:
The duty or work cycle of a transit bus is an optimal application for hybrid technologies. By definition, you can more efficiently manage available power to improve fuel efficiency, lower emissions, reduce noise and better manage parasitic loads simultaneously.
The expanded availability of hybrid vehicles in the light- and medium-duty automotive areas will rapidly move the technology development forward, simply because they have the product volume that will allow the required investment in research and development. The improvements they make will be scalable to our industry in the long term, reducing costs of the technology while increasing product reliability.
The unique nature of the parasitic loads on a bus (lighting, HVAC, customer amenities, high electrical power demand) makes them ideally suited for electrically driven components. These components are inherently more reliable and can be optimized for transit applications.
Since I was a student, fuel cells were the Holy Grail of energy supply. Should the development many hope for be achieved, the hybrid drive is the best platform for a fuel cell propulsion system.
What level of technical support have you received from Orion and BAE Systems?
The engineering and field support from BAE has been excellent. They have incredible core competency in the technical departments. The bus and heavy-duty automotive industries are new to them, so the support infrastructure needs time to mature. But, they are clearly committed to the product and technology. Orion has focused on the bus side of the vehicle and has experienced the challenges any manufacturer has with the maturation of a newly designed product.
What advice would you give other transit agencies considering hybrid-electric buses?
Any new technology will have its problems. It has taken 100 years for the diesel engine to reach its current level of development. There will be unexpected problems.
Prepare your staff. The more familiar people are with the technology and the earlier they are involved in the process, the more accepting they will be.
Nothing is free. The potential improvements from the deployment of any new technology do not occur without some investment and commitment to make it work.
Take small steps. A quantum change in technology throughout a large segment of your fleet will be difficult, if not impossible, to deal with. Introduce new technologies slowly.
Don't reinvent the wheel. If you can gain knowledge and experience from others, seek their help. It is surprising how much trouble and time can be saved by learning from the experience of others.
You must determine what benefit you expect to achieve from the investment. Can you make the business case for the investment in your application?
Make certain you have the tools, training, equipment, infrastructure and human resources to support the new technology.