Causes, Effects, and Mitigation Measures of Time and Cost Overruns in Water Supply Projects: Case of Tigrai Region, Northern Ethiopia

Project cost overrun and schedule delay are major and widespread problems in the construction industry. In Tigrai, most water supply construction projects are not completed within the predetermined contract time and planned budget. Hence, this research was carried out to investigate the causes and effects of time and cost overrun in water supply projects in Tigrai, northern Ethiopia and further recommend effective mitigation measures. A total of 87 questionnaires were distributed, 50 of them were collected, and desk study of 12 water supply projects were conducted. Data were analyzed using relative importance index and statistical software SPSS version 20. Results showed that the most important causes of time overrun were design errors and changes, lack of consistency between bill of quantities and drawings, and change order. Similarly, the most important causes of cost overrun were design errors and changes, lack of consistency between bill of quantities and drawings, and shortage of construction materials and electromechanical equipment in local market. The most effective mitigation measure of the overruns was complete and proper design. Time and cost overrun of the projects ranged between 0 and 203% and between 0 and 25%, respectively. The regression model showed that time overrun was estimated well (r2 = 0.95) using delays caused by design errors and changes and material import. Similarly, cost overrun was estimated well (r2 = 0.98) using factors that affect cost. Overall, the major cause for the overruns was design problem, hence clients and consultants should give due attention for the design process.