A Study of Time and Cost Relationship of Private Building Projects in Abuja

Abstract

Time, cost and quality targets have been identified as the main criteria for measuring the overall success of construction projects. However, previous research shows that little evidence exists of projects where these factors were successfully balanced. How then are the completion times of building projects in Abuja related to their costs? This was the research question of this research, which aimed at achieving a result that will show whether time is effectively related to cost of construction or not. The following objectives were examined: (i) computation of the expected duration of sampled building projects, (ii) determination of the differences between the actual and expected durations and (iii) derivation of an average value for time performance of sampled building projects. Time-cost relationship data for 30 completed private projects in Abuja were obtained from consultant Quantity Surveyors. Objective One was realized by calculating the expected effective duration for each project using the Ogunsemi and Jagboro (2006) model which is given as T = 168.895 + 0.491C (if C ≤ 557) or 709.66 + 0.884C (if C ˃ 557); where T = effective project duration in relation to a given cost from date of site possession to practical completion (in working days) and C = cost of the project (in millions of Naira). From analysis of the research data, it was found that at a given cost, private building projects in Abuja are executed within a duration that is 34% later than the required time. This represents an improvement over the 51% time overrun published in previous works. At the same time, it was found that larger building projects are more susceptible to time underrun. It was recommended that since the time-cost relationship appeared effective in reducing time overrun from 51% to 34%, this should be continuously maintained.