MATHEMATICAL TIME-COST MODEL FOR INSTITUTIONAL BUILDING PROJECTS IN NIGERIA
Baba Shehu Waziri
Department of Civil and Water Resources Engineering
University of Maiduguri, Maiduguri, Nigeria
E-mail: shehuwaziri@yahoo.co.uk
ABSTRACT
The accurate prediction of construction time at the early project stage is essential to incorporate realistic project duration in the bid package. The study investigates the application of the Bromilow’s Time-Cost Model (BTC) to predict the construction duration of institutional building projects in Nigeria. Sixty (60) completed project data were used for the analysis. Linear regression was performed to explain the linear relationship between cost and time variables of the data. The result indicates a strong linear relationship between construction cost and construction duration with coefficients of correlation R= 0.808 and coefficient of determination R2 = 0.670. Double log (log-log) regression was also employed in the form of the BTC model to determine the values of K and β which indicate general level of time performance and the sensitivity of the time performance affected by project size as measured by cost respectively. The low K value of 20.1 demonstrates that the time performance of the construction industry has improved compared to previous surveys while β value of 0.686 indicates a greater influence of project complexity on time prolongation. The model also showed a good fit to the data with R value of 0.845 and R2 value of 0.716. The model showed a satisfactory prediction performance with MAPE of 13.6% over the test sample.
Keywords: Time-Cost, Cost, duration, Bromilow model, regression.