American Society of Civil Engineers


Modeling Cash Flow Profiles with Singularity Functions


by Gunnar Lucko, Ph.D., A.M.ASCE, (Construction Engineering and Management Program, Department of Civil Engineering, The Catholic University of America, Washington, DC 20064) and James P. Cooper, III, (Construction Engineering and Management Program, Department of Civil Engineering, The Catholic University of America, Washington, DC 20064)
Section: Project Planning and Control, pp. 1155-1164, (doi:  http://dx.doi.org/10.1061/41109(373)116)

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Document type: Conference Proceeding Paper
Part of: Construction Research Congress 2010: Innovation for Reshaping Construction Practice
Abstract: The ability to plan and manage cash flows is critical for the survival and long-term economic success of construction contractors. Profiles arise from the interplay of outflows, e.g. labor, equipment, and materials, and inflows, e.g. progress payments less retainage, which very in frequency and are subject to payment terms. Their complex zigzag shape was previously only modeled with simplifications. Approaches included discrete values at specific points in time; averaged S-curves, e.g. from regression; or envelopes of extreme values. Yet neither is suited for cumulative costs of variable schedule activities. This paper therefore describes how cash flow profiles can be flexibly and accurately modeled with singularity functions, which originated in structural engineering. Their components define ranges of behavior between cutoff values. Emphasis is placed on expressing common payment terms, which are illustrated with an example that is validated with the literature. This new approach augments project planning toward an integrated model.


ASCE Subject Headings:
Financial factors
Project management
Contractors