The role of risk attitudes: Discrepancies between human and computer-based risk analysis in the utility sector

To prevent excavation damages to utilities, as well as their negative side effects, the utility construction domain is hammering on the importance of localizing utilities in advance of excavation activities. Until now, the predominantly applied way of locating utilities is to dig trial trenches. Trial trenches expose utilities and are, therefore, considered the only method that grants absolute certainty about the utilities' locations. On the contrary, trial trenches only provide a local measure and thus require understanding about where to dig a trench. This study explores the rationale behind the trial trench method in practice to assess how effective risk on excavation damages is managed by the method. To assess the effectiveness, a computer-based risk analysis tool that calculates the level of excavation damage risk on a given construction site was used as a benchmark. After conducting a practice-based study in which the trial trench method of three Dutch construction projects was observed, the outcomes of the risk analysis tool were compared with the locations of the trenches dug in practice. Findings demonstrate differences: The number of trial trenches dug in practice is remarkably fewer than suggested by the risk analysis, whilst the locations themselves often do not align with where the risks are the greatest. The study shows that a root cause for the differences between the tool and practice is the difference in the motivation behind digging trial trenches. Illustrative examples of these differences show that the adopted risk management approaches are typically guided by both the decision-maker's risk attitude, including their intuition, judgement and expertise of the decision-maker, and time and budgetary constraints. All in all, this study demonstrates that the sense of accuracy provided by employing trial trenches cannot always be taken for granted. This study furthermore urges practice to rethink their excavation damage risk management approaches, whilst recommending the institutional setting to steer their initiatives towards establishing a mindset of careful excavation amongst the practice community.