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April 4, 1997
1. Executive Summary
New Jersey Transit learned the value of introducting new technology to its overhaul of 230 Arrow III electric multiple unit vehicles. It took the risk of converting an existing DC propulsion system to a microprocessor controlled AC system, and implemented dynamic braking in the new design. This risk was managed by utilizing outside expert engineering assistance and conducting Reliability Growth Testing on prototype vehicles, on an independent test track. NJ Transit was rewarded with reductions in operating and maintenance costs.
2. Background
In 1989 NJ Transit began the overhaul of 230 Arrow III electric multiple unit vehicles. This overhaul involved the replacement of the existing DC propulsion package with a state-of-the-art microprocessor controlled AC propulsion system. In addition to the DC-AC conversion, dynamic braking capability was added. The implementation of the above mentioned systems was an engineering challenge which required diligent oversight through the design review phases, first article inspections of major components, and vehicle level functional testing. This process culminated in the administration of a comprehensive reliability growth program.
A. DC-AC Propulsion Conversion
During the planning stages of the overhaul program, NJ Transit was faced with the decision to convert the existing DC propulsion system with a microprocessor controlled GTO inverter propulsion package. Although this technology was relatively new to the United States, many European railroads had already adopted AC propulsion technology with excellent success. After many months of reviewing the benefits and risks associated with AC propulsion, NJ Transit realized the potential advantages, and decided to include the new AC technology in the overhaul specification.
B. Implementation of Dynamic Braking
Once the decision was made to replace the entire propulsion package, NJ Transit saw the opportunity to incorporate dynamic braking into the design. The implementation of dynamic braking would ensure optimal wheel wear and greatly reduce the annual expenses incurred for wheel trueing/change out activities as well as brake shoe consumption. Additionally, NJ Transit would be able to utilize a harder wheel which would provided extended life and associated reduction in costs. However, the implementation of this technology was not without risk, as this was new application to this type of vehicle.
C. Engineering Oversight
The decision to incorporate new technology during the overhaul made it incumbent upon NJ Transit to provide a diligent review of the proposed systems through all stages of development. Comprehensive design reviews needed to be held during the conceptual design phase, which would lead to the development of rudimentary prototypes. The prototypes could then be evaluated and refined to a point that a first article could be produced. First Article Inspection (FAI) activities would be initiated to type test the design, and production go-ahead would be granted. This process would help ensure that the best design solution was provided to NJ Transit.
After completion of the overhaul of the first prototype vehicles, NJ Transit had specified a rigorous acceptance testing program couple with Reliability Growth Testing. This would further validate the design, and provide NJ Transit with quantifiable reliability factors.
3. The Lesson
A. Utilization of Engineering Assistance
NJ Transit recognized, at a very early stage, the need to retain "Engineering Experts" to provide assistance through the overhaul program. This expertise augmented NJ Transit's in-house staff to create to team of individuals with the capabilities to successfully implement this ground breaking program. The decision to create this hybrid team at the onset of the program was invaluable, as it streamlined the progress through the design phases. All members of the team were involved at every step, and this cooperation undoubtedly led to the overall success of the program.
B. Reliability Growth Testing
The overhaul specification contained provisions for conducting Reliability Growth Testing (RGT) on the fourteen prototype vehicles. The RGT was established based upon the vehicles operating in simulated revenue service, on JN Transit property, for a total of 400,000 fleet miles. As the cars were accumulating mileage, all failures were to be recorded and classified according to relevancy. This information would then be compiled to produce interim reliability values. The intent of the RGT was to demonstrate that the vehicles would meet or exceed the specified reliability values, prior to the contractual go-ahead for production. NJ Transit quickly realized that the brief windows of operating time available for this testing would have a tremendous impact on the program schedule, and therefore decided to contract an independent test track, where the RGT would be completed. This decision to utilize a dedicated test track allowed the project team to conduct an exhaustive RGT analysis of the fleet, and provide subsequent release for production.
C. Application of New Technology
The decision to incorporate new technology into the overhaul of these vehicles has been rewarded with reductions in operating and maintenance costs. The philosophy of keeping up with technological advances in all areas has allowed NJ Transit the opportunity to realize savings in component costs, reductions in weight, increases in reliability, and increased functionality.
4. Applicability
The comments and recommendations mentioned above are applicable to all capital procurements and overhaul programs.
5. Reference
The evaluation of new technology, development and implementation has been thoroughly documented through project minutes and project submittals. The data collected as part of the RGT has been compiled into a final report that shows the evolution of the cars reliability through a careful process of failure mitigation through corrective action.
Contact
Mr. Francis P. Bankpo
Director of Capital Programs - Cars
New Jersey Transit
One Penn Plaza East
Newark, NJ 07105
Tel: (201) 491-8265
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