## 6 Conclusions  
This study introduced a stochastic multiskilled resource scheduling (SMSRS) model for scheduling construction projects under resource-constraints considering the impact of risk and uncertainty on activity durations. The SMSRS model was developed by integrating a schedule risk analysis (SRA) model with an existing MSRS algorithm. The SRA model is a simulated-based model that was developed using triangular probability distribution and Monte Carlo simulation with the aid of MS Excel for evaluating the risk and uncertainty inherent in construction activity durations. The resultant stochastic activity durations from the model were used to develop construction schedules with realistic duration using the MSRS algorithm. Additionally, the computational experiment of three projects carried out using the SMSRS model revealed an average deviation of 10.50% in the project duration, indicating the impact of risk and uncertainty on activity durations of the schedule.  
The core contribution of the SMRS model to the body of knowledge is that it enables the project practitioner to evaluate the risk associated with a construction schedule under resource constraint and to determine the realistic schedule duration, thus facilitating informed and proactive decision-making while ensuring that projects are delivered on time and budget. In addition, the SMSRS model will be a valuable tool to the small-scale firms who cannot afford the expensive RCPSP software in:  
1. Estimating accurate activity duration considering the effect of unforeseen events on project outcome;
2. Adequate estimation of the cost of the required resources of project task while preventing the project from cost overrun;
3. Improving activity coordination by experienced multiskilled workers based on the feasible project schedule while ensuring worker safety on-site; and
4. Revolutionizing the site process, adoption of technology, new labor strategy development, improve quality, and client requirement satisfaction.  
Furthermore, in the analysis and scheduling carried out with the SMRS model, small projects limited to only 10-20 activities were examined. Hence, the extension of its application to real mega resource-constrained projects with more than 20 activities is a promising direction for future research. Moreover, to achieve more accurate activity duration simulation, more than 1000 iterations are recommended for the activities of complex projects coupled with the use of a high-speed computer to make activity duration simulation faster. Finally, to reduce computation and scheduling times in case of a mega-scale project, the authors look forward to automating the scheduling procedure using MS excel VBA or a combination of MS excel with programming languages such as PYTHON and MATLAB in the nearest future.  
Conceptualization, M.A.I.; methodology, M.A.I.; software, M.A.I.; validation, M.A.I., M.A.I.; formal analysis, M.A.I.; investigation, M.A.I.; resources, M.A.I.; data curation, M.A.I.; writing--original draft preparation, M.A.I.; writing--review and editing, M.A.I.; visualization, M.A.I.; supervision, B.-S.K.; project administration, B.-S.K.; funding acquisition, B.-S.K. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Research Foundation of Korea (NRF) and funded by the Korea Government (MSIT), grant number: NRF-2018R1A2B6009111.  
Not applicable.  
The authors declare no conflict of interest.