Cost profiling of water infrastructure projects

The expected final budgeted costs of infrastructure assets are often exceeded during project delivery. Being able to determine the likelihood of changes to the final budget can enable clients to implement strategies to manage and control costs during construction. To understand the changing nature of costs, the cost profiles of 1,093 water infrastructure projects that were delivered by a water utility company are examined. Cost overruns were experienced in 656 projects. Only 1 project was delivered on budget with the remaining 436 being completed under the ‘Final Budget Approval’. A mean cost overrun and underrun of +19.97% and -32%, were found, respectively. The ‘best fit’ distribution for cost overruns and underruns for determining their probability of occurrence were calculated. The research moves beyond examining the cost performance of heterogeneous datasets that have dominated previous studies to the use of a homogeneous sample, which enables more reliable contingency forecasts to be determined.