A more adequate methodology for assessing the overall risk of untimely completion (construction and installation works - CIW), taking into account the time horizon of risk occurrence and the phenomenon of risk competition from both probability and impact perspectives, is justified. One of the most common problems in construction projects is delays caused by risks. However, existing research on risk assessment and project schedule analysis overlooks the fact that the aggregate risk depends on the sequence of risk occurrences and their interactions. This article presents a decision algorithm and justifies a computational method for determining the risky duration of work in the project schedule. This information is crucial for making adjustments to the schedule and developing effective risk response strategies. In the calculation examples we have provided, we have demonstrated that our approach differs from the classical method.

Keywords: "probabilistic planning, delays, aggregate risk, risk assessment, uncertainty, construction management, quantitative analysis, timelines, investment projects"