Integration of linear scheduling method and the critical chain project management (original) (raw)
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Repetitive Project Scheduling: Developing CPM-Like Analytical Capabilities
Continuity of work over the successive units is the primary requirement for effective utilization of dedicated resources while scheduling repetitive construction projects. Critical path method (CPM) is the most commonly used method for scheduling construction projects. When CPM is used for scheduling repetitive construction projects, the continuity of work over successive units can not be ensured. To overcome this limitation of CPM in scheduling repetitive projects, a number of resource-driven scheduling approaches have been proposed over last thirty years. Most of these resource-driven scheduling methods are graphical and lack the analytical capabilities. In this paper, a new scheduling methodology to carry out CPM-like analysis is presented. This model ensures maximum possible crew work continuity and enables to determine the floats.
LOB and CPM Integrated Method for Scheduling Repetitive Projects
Repetitive projects require schedules that ensure the uninterrupted usage of resources from a unit to similar units in a repetitive activity while maintaining logical dependency constraints. The critical path method (CPM) is the most widely used and accepted planning and scheduling method for traditional (nonrepetitive) projects. However, CPM does not suit the planning and scheduling needs of repetitive projects. Consequently, resource-driven techniques, such as line of balance (LOB), have been used to schedule repetitive projects that ensure work continuity. LOB is primarily a graphical technique that lacks the analytical qualities of CPM scheduling. A need for an analytical technique fulfilling characteristics of repetitive projects has been reported in the literature. Few attempts have been made to combine the benefits of CPM and LOB techniques in planning and scheduling of repetitive projects. In this paper, an integrated CPM and LOB model has been developed to schedule repetitive projects in an easy nongraphical manner, considering both logic dependency and resource continuity constraints. Overlapping activities of a single typical unit are used to model duration and logical relationships of repetitive activities. The proposed model essentially consists of four steps. In the first step, basic LOB calculations are performed to ensure resource continuity. Activity duration along all repetitive units is calculated in the second step. In the third step, overlapping activities are used to model logical relationships between consecutive activities. Next, CPM time analysis is performed to specify activities' timings and floats and project completion time. An example application is presented to illustrate implementation and features of the proposed model.
Improved Critical Chain Project Management Framework for Scheduling Construction Projects
Construction projects are subject to a wide range of constraints, such as project complexity, resource scarcity, and duration uncertainty. The critical chain project management (CCPM) has emerged as a method for construction scheduling. This paper proposes an improved CCPM framework to enhance the implementation of CCPM in construction project management practices. The framework addresses two major challenges in CCPM-based construction scheduling, including buffer sizing and multiple resources leveling. Buffers play a key role in ensuring successful schedule management. However, buffers generated by the existing sizing methods are either unnecessarily large, which wastes resources, or insufficiently robust against various uncertainties. Resource leveling is another critical challenge in CCPM-based construction scheduling because it requires a fundamentally different approach from the resource leveling used in traditional scheduling methods. The proposed framework improves buffer sizing by integrating into the buffer sizing process various uncertainties that affect construction scheduling but are not factored in by current practice. These uncertainties are assessed in five dimensions with their respective metrics developed in the framework. Furthermore, the framework explores the feasibility of multiple resources leveling in CCPM-based construction scheduling, with a novel method that manages the trade-offs between activity duration and resource usages based on a multimodal activity execution structure. Three case studies were undertaken in this paper. The results showed that the proposed framework outperformed existing buffer sizing methods by generating buffers with reasonable sizes and sufficient robustness against uncertainties. The results also proved the feasibility and effectiveness of performing multiple resources leveling in CCPM-based construction scheduling.
Enhanced Critical Chain Project Management via Advanced Planning & Scheduling Technology
2007
In the late 1990s, a new project management methodology was developed to overcome many of the shortcomings of Critical Path Project Management (CPPM). This new methodology, Critical Chain Project Management (CCPM), is based on methods and algorithms derived from the theory of constraints. The Critical Chain is the sequence of both precedence-and resource-dependent tasks that prevents a project from being completed in a shorter time, given finite resources. If resources (labor/non-labor) are always available in unlimited quantities, then a project's Critical Chain is identical to its critical path. Since the introduction of CCPM, its use has grown considerably and is being applied in more, and more challenging, project management environments. The Critical Chain method, however, is still in its relative infancy and many limitations have been discovered with the current theory and implementation, especially as it has been applied to ever larger project management tasks. Limitations in theory and its current commercial implementations have limited its suitability for large, dynamic, and complex scheduling environments, such as those that have been the focus of advanced scheduling techniques in the past. Many of these limitations can be surmounted by combining the principles of the CCPM methodology with advanced scheduling techniques. This paper investigates how many of the perceived limitations of the Critical Chain method can be overcome and the results maximized by leveraging the power of advanced planning and scheduling. By combining CCPM theory with a sophisticated scheduling technology that combines a variety of scheduling techniques and intelligent conflict resolution, a much more robust solution is possible. Resource constraints, including available equipment, space, and human resources, are very important to the implementation of the Critical Chain method because the greater the degree to which it can take these resources into account, the greater the potential improvement over CPPM. Fortunately, advanced scheduling technology can take into account a variety of resource requirements, and can be adapted to pertinent domain knowledge. This is especially important during the initial Critical Chain analysis step (where the chain length is directly related to schedule quality), and in the execution phase of a CCPM plan, as realtime updates arrive regarding the status of the hundreds or thousands of tasks that make up the plan. A more sophisticated underlying scheduling framework provides two important benefits: it results in a better Critical Chain (one that can potentially be worked in less time), and it is more flexible and better able to accommodate change. We have been able to greatly enhance the practicality and power of the Critical Chain method by leveraging advanced planning and scheduling techniques. By using sophisticated scheduling software as the underpinnings for Critical Chain reasoning, the Critical Chain method can be applied to projects encompassing thousands of heavily constrained tasks and requiring hundreds of different kinds of resources. Giving the Critical Chain method such a solid scheduling basis also allows it to more easily handle complex situations such as new tasks being inserted during the actual plan execution, as well as other radical changes to the situational model.
1 Resource Critical Path Approach to Project Schedule Management
2015
activities with float less than or equal to a specified value, usually zero. Float is the amount of time that an activity may be delayed from its early start without delaying the project finish date. Early start is the earliest possible point in time at which the uncompleted portions of an activity (or the project) can start, based on the network logic and any schedule constraints. Project schedule constraints include resource constraints, finance and supply constraints, calendar constraints and imposed dates. The critical path in the projects with imposed dates and different activity and resource calendars can consist of only one final activity. Managing project schedules, one should pay more attention to activity floats. The activities with shorter floats are more critical than the activities with longer floats. However the float should be calculated with all schedule constraints as well as the network logic taken into account. Most project management packages (with the exception ...
Scheduling is the process of arranging, controlling and optimizing work and workloads in a production process or manufacturing process. Scheduling is used to allocate plant and machinery resources, plan human resources, plan production processes and purchase materials. However, Project schedule management is a management plan that views all project activities as list of project milestones and deliverables. Scheduling of projects, therefore, requires the identification of all of the tasks necessary to complete the project, and the earliest time at which each task can be completed. This Project scheduling Essay therefore expresses the activities there in and the procedures involved. Methods such as critical path Method (CPM) and Gantt chart are clearly illustrated according to [Liberatore et al. 2001] & [Thomas Telford, 1994]
Project Scheduling—Theory and Practice
T he project scheduling problem involves the scheduling of project activities subject to precedence and/or resource constraints. Of obvious practical importance, it has been the subject of intensive research since the late fifties. A wide variety of commercialized project management software packages have been put to practical use. Despite all these efforts, numerous reports reveal that many projects escalate in time and budget and that many project scheduling procedures have not yet found their way to practical use. The objective of this paper is to confront project scheduling theory with project scheduling practice. We provide a generic hierarchical project planning and control framework that serves to position the various project planning procedures and discuss important research opportunities, the exploration of which may help to close the theory-practice gap.
Transportation Research Record: Journal of the Transportation Research Board, 2001
A general model is presented for efficient scheduling and resource management in construction projects that involve a high degree of repetition, such as highways and pipelines. The proposed model has three main features: ( a) it fully integrates the critical path method for network analysis and the line of balance technique for linear scheduling, ( b) it allows realistic schedule development considering project deadline and resource constraints, and ( c) it incorporates improved schedule presentation that shows crews’ movements along the repetitive units and their detailed work assignments. The detailed formulation of the proposed model is described, and an example application is presented. The proposed model is demonstrated to offer significant advantages as a resource-driven approach. Future extensions to the proposed model are then outlined.