Model for Estimating Construction Duration of Public Building Projects in Addis Ababa
No Thumbnail Available
Date
2020-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Predicting project duration with reasonable accuracy is a formidable challenge to industry
practitioners and alike. Consequently, several research studies have focused on this subject, and
thus multiple models have been developed. Notwithstanding the conflicting findings of its
predictive ability, the 50-year-old “time-cost” model of Bromilow (BTC) remains the baseline, to
which the outcomes of most developed models are compared. The Building and Transport
Construction Design Authority (BaTCoDA) had developed a model based on BTC in 1987 for
building projects but it is hardly used in the industry. The objective of this study, therefore, is to
examine the validity, and hence the applicability, of the BTC model to estimate contract durations
for public building projects in Addis Ababa, and to propose an alternative model, taking into
consideration other potentially influential project scope variables on time performance. In this
regard, relevant data for 34 public buildings in Addis Ababa, which were completed during the
period 2010 and 2019, were collected by an archival analysis.
The results of the analysis show that while the BTC model holds true for the projects under the
study, a model with a better statistical significance was developed with gross floor area as a sole
predictor variable. The ρ-value and F-value for the BTC was 0.00019 and 18.403 respectively,
while that of the developed model was 0.000076 and 21.734 respectively. Furthermore, the
adjusted R2 for the BTC was 0.397 while that of the developed model was 0.425 which implies
the developed model was a better fit for the data set. Furthermore, the models were compared with
the model developed by BaTCoDA and the result shows that the model developed based on gross
floor area is superior on account of predictive
Description
Keywords
Construction duration, Bromilow’s Time-Cost model, Regression model