Marimuthu Kannimuthu

Construction companies execute many projects simultaneously. In such situations, the performance of one project may influence the others positively or negatively. Construction professionals face difficulties in managing multiple projects in limited resource situations. The purpose of this study is to identify the problems in multiproject scheduling from the practitioner's perspective and to discover current practices under resource unconstrained and constrained settings. The specific objectives are (1) determining the most challenging issues being faced in handling multiproject environment, (2) enumerating the practices adopted in the industry, and finally (3) identifying the practitioners' perceptions on the multiproject scheduling aspects such as network modeling approaches; activity execution modes; concept of sharing, dedicating, and substituting resources; centralized and decentralized decision-making models; solution approaches; and tools and techniques. An online questionnaire survey was conducted to address the objectives above. The top challenging issues in managing multiproject environment are identified. Factor analysis identified the factors by grouping the variables (a) decision-related, (b) project environment-related, (c) project management-related, and (d) organization-related factors. Resource-unconstrained situation mainly faces the issue of underutilization and wastage of resources leading to lower profit realization. The following findings were identified to overcome the unconstrained resource situation such as identifying the work front, adopting pull planning approach, creating a common resource pool, and allotting it on a rental basis. On the contrary, resource-constrained situation faces the issues of prioritization of resources, coordination, communication, collaboration, quality issues, and rework. The findings suggest the strategies such as top-up via subcontracting, proactive pull planning, introducing buffers, training the culture of the organization towards better communication, coordination, and collaboration, to improve the reliability of achieving baseline project performances. Various multiproject aspects suggested for effective management. The identified problems, practices, and various multiproject aspects are expected to contribute better management of multiproject resource unconstrained and constrained project scheduling.

Companies keep minimal resources such as equipment, labor, and non-renewable materials to maintain productive working capital. This means that resources are constrained, and a multi-project environment adds further complexity since resources have to be shared among projects. Existing project management approaches such as critical path method (CPM), program evaluation and review technique (PERT) etc. are mainly suitable for the unconstrained resource situation. However, industry practitioners are required to handle resource constrained situations and multi-project priorities. Hence, it is important to identify the best practices and systematic approaches used in resource constrained multi-project environment. The objective of ongoing research is to determine the industry practices under resource unconstrained and constrained multi-project settings. An interview with experts and a questionnaire survey were conducted to determine the current industry practices followed for solving project scheduling problems. This research has revealed that resource unconstrained multi-project environment is rare, whereas resource constrained multi-project environment models the real nature of actual projects. When modelled as an unconstrained resource problem, underutilization of resources might occur. On the other hand, in a resource constrained problem, limited resources are shared among project sites, resulting in efficient utilization of resources. The decision process can follow either centralized or decentralized model. A decentralized model is recommended for handling small size projects in a multi-project environment. However, the systematic centralized model is recommended for the large size multi-project environment to optimize the multiple objectives. This study brings out that the current industry practices in India to manage multi-project scheduling problems use_experience based heuristics to accommodate the practical challenges which may not be replicated in other project instances.

Purpose: The purpose of this paper is to develop a framework to optimize time, cost and quality in a multi-mode resource-constrained project scheduling environment. Design/methodology/approach: A case study approach identified the activity execution modes in building construction projects in India to support multi-mode resource-constrained project scheduling. The data required to compute time, cost and quality of each activity are compiled from real construction projects. A binary integer-programming model has been developed to perform multi-objective optimization and identify Pareto optimal solutions. The RR-PARETO3 algorithm was used to identify the best compromise trade-off solutions. The effectiveness of the proposed framework is demonstrated through sample case study projects. Findings: Results show that good compromise solutions are obtained through multi-objective optimization of time, cost and quality. Research limitations/implications: Case study data sets were collected only from eight building construction projects in India. Practical implications: It is feasible to adopt multi-objective optimization in practical construction projects using time, cost and quality as the objectives; Pareto surfaces help to quantify relationships among time, cost and quality. It is shown that cost can be reduced by increasing the duration, and quality can be improved only by increasing the cost. Originality/value: The use of different activity execution modes compiled from multiple projects in optimization is illustrated, and good compromise solutions for the multi-mode resource-constrained project scheduling problems using multi-objective optimization are identified.

Purpose: Construction firms keep minimal resources to maintain productive working capital. Hence, resources are constrained and have to be shared among multiple projects in an organization. Optimal allocation of resources is a key challenge in such situations. Several approaches and heuristics have been proposed for this task. The purpose of this paper is to compare two approaches for multi-mode resource-constrained project scheduling in a multi-project environment. These are the single-project approach (portfolio optimization) and the multi-project approach (each project is optimized individually, and then heuristic rules are used to satisfy the portfolio constraint). Design/methodology/approach: A direct search algorithm called Probabilistic Global Search Lausanne is used for schedule optimization. Multiple solutions are generated that achieve different trade-offs among the three criteria, namely, time, cost and quality. Good compromise solutions among these are identified using a multi-criteria decision making method, Relaxed Restricted Pareto Version 4. The solutions obtained using the single-project and multi-project approaches are compared in order to evaluate their advantages and disadvantages. Data from two sources are used for the evaluation: modified multi-mode resource-constrained project scheduling problem data sets from the project scheduling problem library (PSPLIB) and three real case study projects in India. Findings: Computational results prove the superiority of the single-project approach over heuristic priority rules (multi-project approach). The single-project approach identifies better solutions compared to the multi-project approach. However, the multi-project approach involves fewer optimization variables and is faster in execution. Research limitations/implications: It is feasible to adopt the single-project approach in practice; realistic resource constraints can be incorporated in a multi-objective optimization formulation; and good compromise solutions that achieve acceptable trade-offs among the conflicting objectives can be identified. Originality/value: An integer programming model was developed in this research to optimize the multiple objectives in a multi-project environment considering explicit resource constraints and maximum daily costs constraints. This model was used to compare the performance of the two multi-project environment approaches. Unlike existing work in this area, the model used to predict the quality of activity execution modes is based on data collected from real construction projects.

Resource management in construction projects has many difficulties. Realizing the importance of resource value, identifying the resource value streamline and continuous flow, and adopting the “pull” approach along with perfection can overcome certain difficulties. A better understanding of lean principles through the thought processes and decision making can yield benefit realisation with production capabilities in project environments. This research is aimed at capturing the practitioner perceptions on enabling resource management practices through fundamental lean principles: value, value stream, flow, pull, and perfection. A questionnaire survey was conducted in India. In this survey, information and space have been found to be essential to ensure the performance of critical factors for direct and supportive works. Information and space resources can influence other resources. About one-third of the respondents mentioned that information influences cycle time, lead time, changes, take time, and work in process. The look-ahead plan focuses on eliminating resource constraints to smooth workflow. Root causes derived from raising questions and iterative plan-do-check-act cycle enable continuous improvement process. Lean thinking in resource management can support the effective and efficient use of resources in construction projects.