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Workload fluctuation is one of the challenges facing contracting organizations. Previous studies balanced this fluctuation using capacity adjustment. Most of these studies ignored the simultaneous effect between the direct and indirect variables and the nondeterministic nature of these variables. Moreover, local decisions, i.e. project-based decisions, receive the most attention from contractors. Contrarily, its long-term effect on the organization and its influence on the future project's success receives little attention. This study utilizes a system dynamics approach to holistically address the workload fluctuation of contracting organizations. The model links the pre-award and after-award project phases at the portfolio level. The model is validated through extreme case analysis, units' consistency test, sensitivity analysis test, and industry experts. Results from model analysis inform that the internal behavior and mental model (soft logic) are significantly affecting the long-term performance of contractors more than the external (hard) factors. For instance, the quality level is more important than the initial cash. Also, overhead and markup percent have a significant impact on long-term behavior. Overheads have a relatively more effect on short-term behavior than the markup percent. This research is limited to representing the contracting organization in the execution phase and could be enhanced in the future by incorporating other phases such as design. [ABSTRACT FROM AUTHOR]

The operation and repair of locomotives is characterized by indicators that assess the quality of the repair and maintenance work performed. The article considers a new indicator that characterizes the quality of work of locomotive repair enterprises of service companies. The components of the equation are investigated and the procedure for calculating the coefficient of technical readiness is analyzed. It has been established that there is a time that is taken into account separately for the responsibility of the repair and maintenance company and is Administrative costs. In order to obtain a tool to increase the time spent by locomotives in working condition, it is offered to use simulation dynamic models. The main stages and results of constructing a simulation model of a typical technical inspection point for locomotives are considered. Dependent events were identified and the degree of influence was assessed. The conclusions are drawn that the current version of the simulation dynamic model can be considered a digital twin, because it is a digital copy of the existing physical process for loading the production section. [ABSTRACT FROM AUTHOR]