How has advancement in fuel technologies changed your fleet maintenance procedures?
Fort Worth, Texas
Fort Worth Transportation Authority (The T)
With today’s emphasis on “green” operations, more transit agencies are making the switch to alternative fueled fleets. The T began converting from diesel to compressed natural gas (CNG) in 1988 and today has more than 175 buses that have accumulated 80 million miles with reductions of approximately 1,200 tons of nitrogen oxide and 9 tons of particulate matter.
The advances in CNG fuel technology and equipment manufacturing have improved significantly since we put our first CNG bus on the road, resulting in modifications in maintenance procedures on an ongoing basis.
We have grown from two small compressors at 500 cubic feet per minute (cfm) to five large compressors capable of 3,500 cfm. This allows us to refuel the entire fleet in six hours. By using the fifth compressor as a spare, we also avoid refueling delays due to maintenance. Our expansion with more advanced compressors required the addition of in-house staff for 24/7 maintenance of our fueling service station. The improved efficiency of CNG vehicles has changed the “fill up” frequency of our buses from twice to only once in a 24-hour period.
Procedures in our shop were changed to ensure safety. We installed a system that warns of any methane or carbon monoxide leaks. Should a major leak occur, all personnel are warned to immediately leave while a signal is sent to open all doors and activate the shop ventilation system. This clears the area of gases so that emergency bus repairs may be resumed quickly. These procedures are part of the annual refresher training for all maintenance personnel.
Vehicle maintenance created the greatest changes in our procedures. The original CNG engines were proto-types that were unreliable and received constant updates from the original engine manufacturer (OEM), requiring them to perform most of our maintenance. Over a period of time, the vehicle updates resulted in the engine reliability improving significantly and because of the process The T had put in place, we were prepared to take it over.
So that The T could gradually assume the role provided by the OEMs we set up a process to have our technicians observe every step the OEM techs took in order for us to gain the knowledge and skills we needed to maintain these units. We also sent our techs to training schools and asked the OEMs to send their trainers here. Our goal was to ensure that by the time the warranty period expired on any upgraded vehicle, The T would be fully capable of maintaining its CNG engine.
The advancements in CNG technology have also affected our hiring and training practices, as we now emphasize electronics skills. As a result, The T’s maintenance team won first place for “MCI Multiplex I/O Control” at the 2009 APTA bus conference Roadeo.
We’ve also made changes to the procedures for our preventive maintenance program. Because CNG engines are clean burning, they are susceptible to overheating and causing engine failures. Should the engine parameters exceed specification, an engine could experience catastrophic failure without warning. So, we modified our program to conduct tune-ups every six months. We established checklists that outline exactly what the technician would accomplish without the option of making his own decision. This has proven significant to operating a reliable fleet.
With good maintenance processes in place for advanced CNG technology, we look forward to additional changes to accommodate 10 CNG articulated buses in 2010 that will mean modifying two work bays due to their larger size and fine-tuning bay-availability schedules.
During the early development of CNG transit technology, The T was on its own to find the experts, manufacturers and fuel specialists to help us. Today, an agency can hire a contractor with the know-how and experience to do a turnkey setup for its switch to natural gas.