Assessing the Suitability of Bromilow Time-Cost (BTC) Model to Predict Project Time on Road Construction Projects in Botswana

Abstract

The construction industry researchers have still found the Bromilow Time-Cost performance model given by T = KC^B very relevant to today’s construction processes. The only aspects that change in the model are the coefficient of the equation K, and the power of the cost B. This suggests that the equation characteristics only change with the type of project and the environment in which the project was executed. The model helps to forecast the duration of a project using the estimated final cost of the project. A fast estimate of construction time in the early phase of a project helps the contractor in avoiding time and cost overruns that might lead to dispute and possibly litigation. The motivation for this research was derived from the above assertions. Data for formulating the Bromilow model for road construction projects were collected from a sample of 54 road projects executed by the Botswana Department of Roads. Analysis showed that the Bromilow time-cost performance model for road construction project in Botswana is given by:

T = 14. 11116C^0.155488

With R² = 0.283266 and adjusted R² = 0.269483. Even though the R² and the adjusted R² were considered a good fit for the data and the R² was within the range of what was found in the previous studies around the world which is between 0.205 and 0.850, the model may not provide a good base in Botswana for estimating the duration of a project at the early life when the early cost is known. It is recommended that data on recently completed projects be provided for in-depth analysis of the influence of variables such as funding, payment, rework, change orders , and many other agents of time-overruns might have contributed to project time in the Botswana construction industry.

Keywords: suitability, Bromilow’s model, project time, road construction projects, Botswana

DOI: 10.7176/CER/12-12-04

Publication date: December 31^st 2020