Cost and time overruns in military infrastructure projects - A study of cost and time overruns in military infrastructure between 2011 and 2021

The purpose of the study is to investigate whether there are systematic errors in the cost and time estimates made for military infrastructure projects. Systematic errors means the average deviation for a larger number of projects. The deviation for individual projects can be relatively large, but too high and too low estimates should cancel each other out, on average. The report uses data from 82 projects collected from the Swedish Fortifications Agency digital diary. The results show that the average cost deviation in the first decision step of the infrastructure supply process, the needs assessment (BU), compared to the outcome was 34 %. The corresponding figure for the second step, preliminary investment agreement (PI), was 26 %. When the project reached the final decision stage, the final investment agreement (SI), and the deviation was only 3 %. The conclusion from the analysis is that there are systematic errors in the first two process steps, the BU and the PI, but not in the SI. The results are similar for the time deviations. The delay between the estimated date of access and the actual date of access was just under two years in both BU and PI. The corresponding figure for SI was around four months. All process steps have systematic errors because the deviation is statistically significantly different from zero. Seen from a larger perspective, however, four months is a relatively small deviation, which means that the significance of the deviation in SI is rather minor.