Construction work often involves risks when carrying out complex sets of tasks described in the form of network schedules, in particular, risks of violating tender deadlines and project costs. One of the main reasons for increased project risks is a lack of resources. The main objective of this study is to develop a methodology for modeling network schedules under resource constraints, taking into account the stochastic influence of risks on project completion deadlines. The paper analyzes tools for modeling project schedules; describes a mathematical model for estimating project cost based on a network schedule under resource constraints; proposes a method for modeling a network schedule in the AnyLogic environment; develops an algorithm for modeling parallel branches of a project schedule under resource constraints; and describes a method for modeling a network schedule for project work. Testing was conducted based on a network schedule for a project to construct a contact line support. It has been shown that the method allows for obtaining probabilistic estimates of project deadlines and costs under conditions of risk and limited resources. The methodology can be applied to various projects described by network schedules and will allow solving a number of practical tasks: optimizing resources allocated for project implementation, taking into account the time and cost of the project, analyzing risks affecting project implementation, and developing optimal solutions for project risk management.

Keywords: network schedule, work plan, simulation modeling, risk analysis, project duration, project cost

Often in practice, construction times are estimated using deterministic methods, for example, based on a network schedule of the construction plan with deterministic values for the timing of specific works. This approach does not reflect the reality associated with the probabilistic nature of risks and leads to a systematic underestimation of the time and, as a consequence, the cost of construction. The research proposes to use a Markov discrete heterogeneous Markov chain to assess the risks of non-completion of construction in due time. The states of the Markov process are proposed to correspond to the stages of construction of the object. Probabilities of system transitions from state to state are proposed to be estimated on the basis of empirical data on previously implemented projects and/or expertly, taking into account the risks characterising construction conditions in dynamics. The dynamic model of the construction plan development allows to determine such characteristics as: the probability of the construction plan realisation within the established terms, the probability that the object will ever be completed, the time of construction to the stage of completion with a given degree of reliability; unconditional probabilities of the system states (construction stage) in a given period of time relative to the beginning of construction. The model has been tested. The proposed model allows us to estimate the time of completion of construction, to assess the risks of failure to complete construction within the established deadlines in the planned conditions of construction realisation, taking into account the dynamics of risks.

Keywords: construction time, risk assessment, markov model, discrete Markov chain, inhomogeneous random process

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