Queueing Theory and Process Flow Performance

Chang-Sun Chin1

1Ph.D., Honorary Fellow, Construction Engineering and Management Program, Department of Civil and Environmental Engineering, University of Wisconsin, Madison, [email protected]


Queuing delay occurs when a number of entities arrive for services at a work station where a server(s) has limited capacity so that the entities must wait until the server becomes available. We see this phenomenon in the physical production environment as well as in the office environment (e.g., document processing). The obvious solution may be to increase the number of servers to increase capacity of the work station, but other options can attain the same level of performance improvement. The study selects two different projects, investigates their submittal review/approval process and uses queuing theory to determine the major causes of long lead times. Queuing theory provides good categorical indices—variation factor, utilization factor and process time factor—for diagnosing the degree of performance degradation from queuing. By measuring the magnitude of these factors and adjusting their levels using various strategies, we can improve system performance. The study also explains what makes the submittal process of two projects perform differently and suggests options for improving performance in the context of queuing theory.


Process time, queueing theory, submittal, variation, utilization



Chin, C. 2009. Queueing Theory and Process Flow Performance, 17th Annual Conference of the International Group for Lean Construction , 247-256. doi.org/

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