An Inclusive Probabilistic Buffer Allocation Method

M. Poshdar1, V. A. González2 & Sheila Belayutham3

1MSc, PhD Candidate, Department of Civil and Environmental Engineering, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand (corresponding author). E-mail address: mpos814@aucklanduni.ac.nz
2PhD, Senior Lecturer, Department of Civil and Environmental Engineering, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. E-mail: v.gonzalez@auckland.ac.nz
3MSc, PhD Candidate, Department of Civil and Environmental Engineering, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. E-mail address: sbel594@aucklanduni.ac.nz

Abstract

The use of buffers in construction presents a tension between theory and practice. From a lean theoretical standpoint, buffers represent waste while they are an elemental part of construction schedules in practice. As a result, a reasonable balance is required to be established between the undesirable waste created by overusing buffers, and high risk of time/cost overruns generated by the lack of buffers. The balanced allocation of buffers includes two main aspects: Determining the size and the location of buffers in the planned schedule. These two factors are significantly affected by the general scheduling policy undertaken to determine the start time of activities. Also, both factors are dependent on the selected set of objectives in the project. Traditional buffer allocation techniques in construction have been informal and often inconsistent in addressing the buffer balancing issues. In this paper, an Inclusive Probabilistic-based Buffer Allocation method (IPBAL) is proposed which applies a mathematically driven strategy to resolve the balanced state in using buffers in construction schedules. It suggests a solution for the multi-objective buffer allocation problem that also accounts for the general scheduling policy. Hence, the method enables shielding the project activities against variability that is one of the steps required to implement lean in construction.

Keywords

Variability, Buffer, Time compression, Scheduling, Network analysis

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Reference

Poshdar, M. , González, V.A. & Belayutham, S. 2015, 'An Inclusive Probabilistic Buffer Allocation Method' In:, Seppänen, O., González, V.A. & Arroyo, P., 23rd Annual Conference of the International Group for Lean Construction. Perth, Australia, 29-31 Jul 2015. pp 183-192

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