Cost and schedule overruns in large hydropower dams: an assessment of projects completed since 2000

This paper presents novel data on cost and schedule overruns in recent dam projects started and completed since 2000 and compares them with pre-existing data sets on projects started before 2000. Combining these data, a meta-data set was created of 184 cost overrun and 191 time overrun data points. For post-2000 projects, the average cost overrun was 33% and schedule overrun was 18% as compared with 46% and 37% respectively for pre-2000 projects. While a decrease in the averages was observed, the change in cost overruns is not statistically significant, whereas the change in time overruns is significant.