Buffer sizing for the critical chain project management method

 

 

A. Geekie^I; H. Steyn^II

^ISasol Technology Project Management, Sasol Technology, South Africa adrian@geekiegroup.com
^IIDepartment of Engineering and Technology Management, University of Pretoria, South Africa herman.steyn@up.ac.za

 

 

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ABSTRACT

Methods for sizing project and feeding buffers for critical chain project management are investigated. Experiments indicate that - in the absence of bias, and for certain classes of bias - buffer consumption is independent of the mean duration of a chain. Generally the popular method - a buffer size equal to 50% of the longest path leading to it - gives rise to excessively large buffers. Buffers sized according to the square root of the sum of squares perform well in the absence of bias, but with bias present the performance is unacceptably poor. A new approach to buffer sizing is proposed.

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OPSOMMING

Metodes vir groottebepaling van projek- en saamvloeibuffers vir kritieke-ketting projekbestuur word ondersoek. Eksperimente dui daarop dat - in die afwesigheid van onewewigtigheid, en vir sekere tipes onewewigtigheid - bufferverbruik onafhanklik is van die gemiddelde lengte van 'n ketting. Oor die algemeen veroorsaak die metode van buffergrootte - gelyk aan 50% van die langste pad wat tot die buffer lei - onnodige groot buffers. Buffers bepaal met die metode van die vierkantswortel van die som van kwadrate, vaar goed in die afwesigheid van onewewigtigheid, maar vaar onaanvaarbaar swak wanneer onewewigtigheid teenwoordig is. 'n Nuwe metode vir die bepaling van buffergrootte word voorgestel.

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1 The author was enrolled for the MPM programme at the Department of Engineering and Technology Management, University of Pretoria