Professor Howard Weiss, creator of our Excel OM and POM for Windows software, provides his monthly guest post.
The Maintenance chapter of your Heizer/Render/Munson text points out that “poor maintenance can be disruptive, inconvenient, wasteful and expensive in dollars and even in lives”. The Washington DC metro is a prime example of this situation. Last month, a DC Metro train derailed. Fortunately, only one of the 187 passengers was hospitalized. The derailment was caused because the original specifications for manufacturing the wheels for the most recently purchased cars, the 7000 series, were not correct. The new cars went into service in 2015 and have been received in batches since then.
The Metro agency had received approximately 470 7000-series railcars by the end of 2017, 610 by the end of 2018, around 730 by the end of 2019, and all
748 delivered by the end of 2020. Correspondingly, as more 7000 series cars entered the system, the failure rate on the axles has increased from .01% in 2017 to 1.3% in 2021. Typically, about 150 cars are in maintenance on any day but due to the derailment, all 748 of the newest cars were pulled from service causing the Metro to operate with only 22% of its fleet.
Your text notes that to improve reliability individual components should be improved. This was the case with the cars in that the specifications improved for the most recent batch of cars that were delivered. The book also notes that improving preventive maintenance is useful. This is what the Metro is now doing for the 748 cars removed from service.
Classroom discussion questions:
- How might the Metro increase its car capacity during this inspection time.
- What are the repercussions of the fleet being reduced to 22% of normal?