Forecasting construction durations for public housing projects: a Hong Kong perspective

The past thirty years have seen a great surge of international attention and discussion in the domain of construction time performance of building projects. Demand for residential construction has been continually increasing in Hong Kong since the 1950s, while an accelerated demand has been envisaged in the next few years up to 2001. This paper is based on the findings of the third survey in an investigation which aimed at determining a group of critical factors that affect construction durations of building projects in Hong Kong. This stage of the study attempted to generate standards (norms) for overall completion periods of public housing blocks, by modelling the durations of the primary work packages in the building construction process, i.e. piling, pile caps/raft, superstructure, EandM services, finishes and their respective sequential start-start lag times, in terms of the identified sets of critical factors (significant variables). Data from 15 case studies of standard New Cruciform type housing blocks was collected from the client and contractors. Multiple Linear Regression was applied in analyzing the project data and formulating a construction duration model. The forecasting performance of the model was next evaluated using an independent (new) set of project information from the client, in terms of a relative measure known as the Percentage Error. Both the general applications and drawbacks of the model are briefly presented and examined herein. The low values of percentage error (less than about ±10%) for overall construction durations confirmed that the model can be a reliable tool for predicting the construction durations of public housing projects in Hong Kong; and the research methodology used could well be extended to similar studies and duration forecasts in other sub-sectors in Hong Kong, as well as in other countries.