APPLICATION OF BROWMILOW’S TIME-COST (BTC) MODEL TO HIGHWAY PROJECTS IN NIGERIA

Practitioners and researchers have long recognised the significance of time and cost of construction as crucial to project feasibility assessment and budget allocation decisions. Therefore it is imperative for clients and contractors to obtain reliable and accurate estimates of both time and cost at the planning phase of a project. This study examined the application of Browmilow's Time-Cost (BTC) model for the prediction of highway construction time in Nigeria using a set of completed projects database. Linear regression was performed to investigate time-cost relationship of the data. The result revealed a positive correlation between the variables with R and R2 values of 0.734 and 0.549 respectively. A log-log regression in the form of the BTC model was developed to determine the value of K which showed general level of time performance and β which demonstrated the sensitivity of time performance as affected by project size measured by cost. The result indicated a K value of 2.8 which is very low compared to values obtained in previous studies for other categories of construction. The β value of 0.53 indicates a greater influence of project complexity on the prolongation of time of construction. The model demonstrated a good fit to the data with R value of 0.736 and R2 value of 0.542. The model also showed a weak prediction efficacy with a Mean Absolute Percent Error (MAPE) of 19% over a test sample which is considered inadequate for application in practice. The potential limitation of the model is that it does not consider other factors apart from cost that have effect on construction time.