Formulating construction cash flow curves using a reliability theory analogy

Prediction of cash flows during construction of large buildings is usually based on cumulative cashflow in the form of an S-curve. There have been several attempts to establish formulae for the estimation of such S-curves on an empirical basis. This paper draws an anlogy between the probability of failure in reliability theory and the probability of payment during construction to develop a general approach to possible mathematical forms of the cashflow during construction. An example of a new generalized alternative form of the S-curve known in Australia as the Bromilow S-curve is shown to be an excellent approximation to the empirical form.