The relationship between economic indicators and Bromilow's time-cost model: A pilot study

The existing heuristic-based estimation of construction time has been considered as inefficient, and could result in disparity between the actual construction time and the contract duration. An empirical study carried out by Bromilow in 1969 on time-cost relationship has led to the development of a forecasting model (BTC model) for construction duration based on the cost of the project. Since the pilot study by Bromilow in 1969, further studies on the BTC model have been conducted in 1977, 1980 and 1988. The results of these studies indicated that the construction speeds are constantly changing as a result of the changing economic conditions. In this paper, the BTC model is refitted with a new set of 93 Australian construction projects between 1991 and 1998. The aim of this pilot study is to investigate the relationship between the BTC model (i.e. construction speed) and commonly used economic indicators in the construction industry. The results indicate that the construction speed (i.e. K value in the BTC model) is positive correlated to some economic indicators.