A Coal Unloader: A Finite Queueing System with Breakdowns

The Detroit Edison Company owns and operates the coal-fired Monroe Power Plant. Coal is generally brought by train to the plant from mines in nearby states and is unloaded by a single unloader system. There were difficulties in meeting the plant's coal needs with the existing rail transport system. Management observed frequent queues of trains at the unloader system which they attributed to breakdowns of the unloader system. A queueing model was developed to explore the impact on the system of unloader breakdowns and the potential benefits associated with adding a second unloader system. The model was also used to study the relationship between the number of trains, coal throughput, and queueing delays.