Rapid Analysis of Queueing Systems (RAQS)


RAQS is a software package for analyzing general queueing network models based on a two-moment framework. It is a Windows application and is written in C++.  It supports instruction and research in queueing systems and is suitable for both undergraduate and graduate students. RAQS was the final product of a project that was funded by the National Science Foundation under the Engineering Research Deployment Teaching Initiative Program (Grant No. DDM-9311357) during 1993-94.  Additional support was provided by the AT&T Foundation through a grant to the Center for Computer Integrated Manufacturing.  RAQS is maintained by Dr. Kamath and his CCiMe graduate assistant, with a new version released every two to three years as shown in the RAQS timeline.

  • 1993-94      NSF grant initiates the development of RAQS

  • 1995           First full version of RAQS available on the Web

  • 1996           Version 2, a 32-bit version of RAQS available on the Web

  • 1998           Software fixes to accommodate Windows 98, Second Edition

  • 1999-2000  Development of a new GUI and text file input option

  • 2001           Version 3, called RAQS2001 available on the Web

RAQS implements the parametric decomposition (PD) approach and its extensions for solving single and multiclass open queueing networks.  The PD approach was made popular by Whitt’s Queueing Network Analyzer publications shown below.

  • Segal, M. and W. Whitt.  1989.  A queueing network analyzer for manufacturing.  Proceedings of the 12th International Teletraffic Congress, Torino, Italy, June 1988, 1146-1152.
  • Whitt, W.  1983.  The queueing network analyzer.  Bell Systems Technical J.  62  2779-2815.

 The following is an early publication that describes the basic features of the RAQS software.

  • Kamath, M., S. Sivaramakrishnan, and G. Shirhatti, 1995, “RAQS: A software package to support instruction and research in queueing systems,” 4th Industrial Engineering Research Conference Proceedings, pp. 944-953, IIE, Norcross, GA.


RAQS also implements the extension of the PD approach to closed queueing networks and tandem finite buffer networks developed by Prof. M. Kamath.  Some of the publications and presentations that document the PD approach for closed queueing networks and tandem finite buffer networks are listed below.




Kamath, M., 1994, “Recent developments in modeling and performance analysis tools for manufacturing systems,” In Computer Control of Flexible Manufacturing Systems, (S. Joshi and J. Smith, Eds.), Chapman & Hall, London, pp. 231-263.

Suri, R., J.L. Sanders, and M. Kamath, 1993, “Performance evaluation of production net¬works,” in Handbooks in Operations Research and Management Science, Vol. 4: Logistics of Production and Inventory, (S.C. Graves et al., Eds.), Elsevier Science Publishers, B.V., pp. 194-286.

Basnet, C. and M. Kamath, 1991, “A two-moment queueing network model for flexible manufacturing systems with transport vehicles,” Proceedings of the First Joint Conf. of the Operational Research Society of New Zealand & the New Zealand Production and Inventory Control Society, pp. 7-12.

Kamath, M. and J.L. Sanders, 1991, “Modeling operator/workstation interference in asynchronous automatic assembly systems," Discrete Event Dynamic Systems: Theory and Applications, Vol. 1, pp. 93-124.

Kamath, M. 1990, “Analytical performance modeling of asynchronous automatic assembly systems,” Proceedings of the 1990 International Industrial Engineering Conference, IIE, Norcross, GA, pp. 557-562.

Kamath, M., R. Suri, and J.L. Sanders, 1988, “Analytical performance models for closed loop flexible assembly systems,” The International Journal of Flexible Manufacturing Systems, Vol. 1, pp. 51-84.

Kamath, M. and J.L. Sanders, 1987, “Analytical methods for performance evaluation of large asynchronous automatic assembly systems,” Large Scale Systems in Information and Decision Technologies, Vol. 12, No. 2, pp. 143-157.

Kamath, M. and J.L. Sanders, 1986, “Analysis of asynchronous automatic assembly systems with bottleneck stations,” SME-Systems I Conference Papers, Chicago, IL.



Kamath, M., S. Sivaramakrishnan, and G. Shirhatti, 1995, “A 2-moment approach for solving multiclass closed queueing network models of manufacturing systems,” INFORMS New Orleans Fall 1995.

Kamath, M. 1995, “RAQS: a software package for rapid analysis of queueing systems,” INFORMS New Orleans Fall 1995.

Kamath, M.,1992, “A two-moment approximation for solving tandem queueing networks with finite buffers,” ORSA/TIMS Joint National Meeting.

Kamath, M. and J.L. Sanders, 1989, “Operator/station interference models for automatic assembly systems,” ORSA/TIMS Joint National Meeting.



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