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... If the effect is found, the hypothesis is strengthened. The five main steps of the TOC described by Goldratt (1997) are as follows: (1) identify the system's constraint(s); (2) exploit the identified constraint(s); ...
... So, in this method, the first step is to determine the activities with limited resources, also called the project's constraint or bottleneck. A bottleneck (constraint) in a project can be determined by performing the following steps proposed by Goldratt et al. (1992), Goldratt (1997), andWoeppel (2006): (1) map out the processes or a flowchart of the entire project; (2) identify parts of the process where there are the longest delays for the project and identify the weakest link in the project, which is the activity holding back the project the most; (3) map part of the project determined in Step 2 in more detail by going down to lower levels of the project, look at the process in the project and identify the activity that is not working as efficiently as it should be; (4) look carefully for the true constraint-often a lack of availability of a specific skill or piece of equipment; and (5) use root cause analysis (RCA) to identify the cause of the constraint and how to improve it. In order for an activity not to become a bottleneck, the activities ahead of it that are feeding it must continually supply enough material. ...
... Project buffer, on the other hand, is located at the end of the project to protect the project deadline against violations in the CC. The project duration is usually calculated as the difference between the CC duration with contingency and CC duration without contingency multiplied by a factor, usually 50% (Goldratt 1997). In the project presented in Fig. 2(b), the PB is 2 days [ð18 days-14 daysÞ × 50%]. ...
Article
In this paper, a novel framework is presented for estimating, allocating, and managing schedule contingency using the theory of constraints and the earned schedule technique. The main aim of the proposed framework is to present a practical technique to manage schedule contingency in a manner that is easy to use and simple to understand; can overcome the drawbacks of earned value management for the schedule component; can overcome the inaccuracy caused by using critical path method; and takes into account the statistical nature of each activity and merges them to form a single framework. The framework introduces two new measures, buffer performance index and buffer variance, for measuring the expected remaining buffer and the actual remaining buffer on critical and noncritical chains based on the percentage completion for each activity at the end of the reporting period, respectively. To verify the proposed framework, the processes and measures have been applied to three projects, each with different complexities. The results show potential for managing buffers when placed at the project level, without the involvement of complex mathematical models or tedious equations.
... Others focus on how to dynamically adapt the amount of contingency to the existing risk throughout the project (Godfrey 2004;Noor, Tichacek 2009;Howell 2012). A number of studies provide information about the decision-makers who are involved in contingencies management (Ford 2002;Laryea, Hughes 2011) or about the transparency of contingencies (Smith, Bohn 1999;Leach 2003;Chan, Au 2009;Laryea, Hughes 2011;Goldratt 1997;Yeo 1990;Thompson, Perry 1992;Baccarini 2004). However, despite the previously mentioned relevancy of opportunities management, most of the authors use the term "risk" synonymously with the term "threat" (Dake 1992;Chapman, Ward 2003). ...
... Contingencies may be hidden within cost estimates and work schedules through inflated unit costs or longer task durations (Smith, Bohn 1999;Leach 2003;Chan, Au 2009;Laryea, Hughes 2011). Alternatively, they may be explicit, as a fixed percentage line added to the base estimate (Yeo 1990;Thompson, Perry 1992;Baccarini 2004) or as time buffer allocated at some point along the critical path of the schedule (Goldratt 1997). Furthermore, contingencies may be explicitly defined for each cost item or task (Smith, Bohn 1999;Leach 2003; Chan, Au 2009; Laryea, Hughes 2011), or for the whole project as a generic amount of time or money (Yeo 1990;Thompson, Perry 1992;Baccarini 2004). ...
... Risk in construction field Seung and Hyung (2004); Ballard (2005) (2011); Goldratt (1997); Yeo (1990); Thompson and Perry (1992); Baccarini (2004) Generic and specific contingency Smith and Bohn (1999); Leach (2003); Chan and Au (2009); Laryea and Hughes (2011); Yeo (1990); Thompson and Perry (1992); Baccarini (2004) ...
Article
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The management of threats and opportunities plays a key-role in enhancing project performance. However, there is a gap in literature concerning how general contractors manage threats and opportunities in construction projects, in particular in the use of time and cost contingencies. This research partially addresses this gap through a case study of two large Spanish construction companies. The research presented two key factors determining how the contractors analyzed manage time and cost contingencies: project objectives and existing mistrust among the contractor’s team members. The research also found that managers use time and cost contingencies not only to manage threats, but also as tools for managing opportunities, thereby providing insight into a previously undescribed form of contingency: the negative contingency. The research results enable a better understanding of the actual behavior of general contractors, which contributes to paving the way for developing enhanced methods for contingencies management.
... Among the many project management techniques dealing with uncertainty, the theoretical and practical aspects of Goldratt's critical chain scheduling and buffer management (CC/BM) methodology -the direct application of the theory of constraints (TOC) to project management -have received considerable attention (Goldratt, 1997;Ma et al., 2014;Zhang et al., 2016Zhang et al., , 2018. CC/BM is deemed to be a favorable and proactive approach for scheduling resource-constrained projects under uncertainty by inserting various types of buffers; further, it offers a reasonable, reactive tool for project control based on buffer monitoring during the execution process (Vanhoucke, 2012;Zheng et al., 2018). ...
... It is the restricting element (bottleneck) of a project schedule and needs the maximum protection. In the book by Goldratt (1997), and in most other papers, an arbitrary choice is typically made if there is more than one CC. While this is irrelevant in the context of deterministic scheduling, where the project makespan (i.e., the CC length) is fixed, it becomes a compelling issue when uncertainty is explicitly considered; this is because the choice of CC impacts the robustness of the CC/BM schedule (Bruni et al., 2017). ...
... BM is the other core element of CC/BM. Goldratt (1997) recommends the concentration of safety time in a project buffer (PB) and feeding buffers (FBs) to reduce the uncertainty in a realistic project. The sizing and monitoring of buffers, thus, play a crucial role in ensuring that the project meets the predefined deadline and improving the stability of the project plan. ...
Article
In the past decades, the critical chain scheduling and buffer management (CC/BM) methodology has gained widespread acceptance as an emerging project planning and control technique. This paper first presents six priority indices for selecting the optimal critical chain when more than one such chain is possible. Next, we examine four schedule generation schemes for rescheduling, along with two control actions (i.e., expediting work to shorten activity durations and adding emergency resources to bring forward activity start times) for repairing a critical chain schedule whenever activity delays cross the buffer threshold. The main results of our computational experiments include the non-negligible impact of different critical chain sequences on the project robustness measures, the appropriate level of feeding buffer sizes, and the trade-off between different reactive responses in relation to the cost factors or management preferences.
... Over the past two decades, Critical Chain Project Management (CCPM) has attracted extensive attention in both business and the academic field, resulting in a lot of achievement (Ghaffari and Emsley 2015). The fundamental principle of CCPM is to use the critical chain instead of a traditional critical path, to insert a project buffer at the end of the project and to insert feeding buffers wherever non-critical chains join the critical chain to protect a timely project completion (Goldratt 1997). As we all know, the critical path is the longest path when only considering the precedence constraints in a project. ...
... Once a critical chain is identified, a project buffer and some feeding buffers are needed to be inserted into the project network to protect the project. The most classical buffer sizing methods are Goldratt's 50% buffer sizing rule (later, other authors called it the Cut and Paste Method, C&PM) and Newbold's Root Square Error Method (RSEM) (Goldratt 1997;Newbold 1998). Since then, many methods have been proposed for improving buffer sizing (Tukel et al. 2006;Ashtiani et al. 2007;Bie et al. 2012;Jovanović et al. 2017). ...
... Typically, roadrunner scheduling which is also named roadrunner mentality (Goldratt 1997) is applied during the execution of CCPM. Here, we also used roadrunner scheduling as our project execution policy. ...
Article
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The fundamental principle of critical chain project management is to use the critical chain instead of a traditional critical path, to insert a project buffer at the end of the project and to insert feeding buffers wherever non-critical chains join the critical chain to protect a timely project completion. Due to the complexity of project, inserting feeding buffers may cause a conflict, such as precedence conflict or resource conflict, which can be solved by rescheduling. However, after rescheduling some new problems may arise: non-critical chain may start earlier than critical chain (non-critical chain overflow), or a gap may occur between activities on the critical chain (critical chain break-down). This paper is aiming to solve these new problems by a two-stage approach combined with feeding buffer for rescheduling. In the first stage, a first-stage rescheduling based on priority rules together with a backward-recursive procedure is proposed for rescheduling to solve resource and precedence conflicts, resulting in a critical chain break-down or a non-critical chain overflow. In the second stage, a second-stage rescheduling based on a heuristic algorithm is proposed to eliminate new problems and generate a better rescheduling scheme. Finally, we do simulations on the 110 Patterson instances set to verify the feasibility, effectiveness and applicability of our two-stage approach for rescheduling. Simulation results show that, it is an effective approach to generate reliable rescheduling schemes in most projects with excellent performances, i.e. the average project length, timely project completion probability and etc.
... This theory is a management philosophy that proposes focusing on constraints is a better strategy to achieve the goal. The idea of CCPM was first introduced by Eliyahu M. Goldratt in 1997 [20]. After its introduction, many researchers have studied the efficacy of CCPM. ...
... Alternatively, the traditional uncertainty management approach of PERT/CPM is also lacking. In this traditional process, schedulers create "safety time" or a "safety margin" to protect against project growth during execution caused by unknowns, often based on worst case scenarios [20]. This results in project uncertainties being "buried" and unrealistically long project durations [33]. ...
... This is illustrated from the following quote, "CPM is as scheduling method to identify the shortest time a project could be accomplished assuming resources are Infinite, whereas CCPM is a method of planning and managing projects that put the main emphasis on the resources required to execute project tasks" This implies that CPM alone does not make sense for field resource allocations and supports this paper's use of CCPM as a more applicable scheduling analysis tool for EPC megaprojects [30]. Goldratt [20] and others pointed out with rectifiable reasons that the reliance on CPM as the sole schedule planning methodology frequently causes projects to miss deadlines and commitments to stakeholders. A major risk omitted from mitigation in CPM is the contention for scarce resources [34]. ...
Article
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Engineering, Procurement, and Construction (EPC) of oil and gas megaprojects often experience cost overruns due to substantial schedule delays. One of the greatest causes of these overruns is the mismanagement of the project schedule, with the piping works (prefabrication and installation) occupying a majority of that schedule. As such, an effective methodology for scheduling, planning, and controlling of piping activities is essential for project success. To meet this need, this study used the Critical Chain Project Management (CCPM) to develop a piping construction delay prevention methodology, incorporating material procurement processes for EPC megaprojects. Recent studies indicate that the traditional scheduling method used on oil and gas mega projects has critical limitations regarding resource scarcity, calculation of activity duration, and dealing with uncertainties. To overcome these limitations, the Theory of Constraints-based CCPM was proposed and implemented to provide schedule buffers management. Nonexistent in literature, and of critical importance, is this paper’s focus on the resource buffer, representing material uncertainty and management. Furthermore, this paper presents a step-by-step process and flow chart for project, construction, and material managers to effectively manage a resource buffer through the CCPM process. This study extends the knowledge of traditional resource buffers in CCPM to improve material and procurement management, thus avoiding the shortage of piping materials and minimizing delays. The resultant process was validated by both deterministic and probabilistic schedule analysis through two case studies of a crude pump unit and propylene compressor installation at a Middle Eastern Refinery Plant Installation. The results show that the CCPM method effectively handles uncertainty, reducing the duration of piping works construction by about a 35% when compared to the traditional method. Furthermore, the results show that, in not considering material uncertainty (resource buffers), projects schedules have the potential for approximately a 5% schedule growth with the accompanying delay charges. The findings have far-reaching applications for both oil and gas and other sectors. This CCPM case-study exemplifies that the material management method represents an opportunity for industry to administrate pipeline installation projects more effectively, eliminate project duration extension, develop schedule-based risk mitigation measures pre-construction, and enable project teams to efficiently manage limited human and material resources.
... Critical Chain is a project management method that focuses primarily on the management of the duration of activities, considering the allocation of resources, and is based on the principles of the Theory of Constraints (TOC). This method was initially proposed by Goldratt (1997) and later detailed by others (Blackstone, Cox, & Schleier, 2009;Leach, 2000;Peng & Jin, 2009;Steyn, 2000). ...
... Complexity and uncertainty are two of the main characteristics of any project and, according to Goldratt (1997) and Leach (2000), because the CCPM method focuses on eliminating the additional security time, it is suitable for application in environments of projects with high complexity and uncertainty. ...
... This may be an indication that the initial estimated time of the project has built-in security, as explained by Leach (2000). In this case, it was 13.8% less than the estimated time, which provides evidence that the CCPM method reduces the embedded additional security on the estimated time of initially planned activities, thus minimizing the impact that the student syndrome and Parkinson's law have over the estimated time of activities (Goldratt, 1997 Figure 4. Allocation of critical resources on a multiproject system. ...
Article
In 1997, Eliyahu Goldratt proposed a method called critical chain project management (CCPM) to minimize the inefficiencies identified in traditional project management. The project management community accepted the proposed method as a viable alternative. However, to allow its implementation with a multiproject system, more research was necessary. Seeking to identify the key factors that influence the performance of the multiproject system applying the CCPM method, we performed a case study. Logistic regression analysis showed that applying the CCPM method in a multiproject system allows for better time estimation of activities and facilitates the allocation of critical resources.
... The Theory of Constraints (TOC) is a methodology widely applied in process improvement of manufacturing processes [11,20,23,24]. According to [6,7,17], the TOC can be described as a philosophy of continuous improvement, which has evolved and expanded its methodological basis over time. TOC has been the subject of a substantial amount of research involving its application to the manufacturing process. ...
... TOC states that every system has at least one constraint [6,7,9]. A constraint is any value that can prevent a system from achieving its goal [9]. ...
... A constraint is any value that can prevent a system from achieving its goal [9]. According to [6,7], a constraint can be external (not physical) or internal (physical). The external constraints are usually associated with circumstantial problems, such as: (1) market demand: production over market capacity or production below market capacity; and (2) a corporate procedure: in this case, a decision or a procedure that limits the gain. ...
Conference Paper
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This paper presents the quali-quantitative results of a study on the identification of bottlenecks in the software development process. The research was developed in an environment learning of Software Engineering and had the collaboration of students of the Department of Computer Science (DCC) of the Federal University of Rio de Janeiro (UFRJ). The main objective of the research is to verify the existence of productive bottlenecks in Software Development Process (SDP), typify them and if possible to promote treatments to solve the impacts in the process and in the software product. For this, three experimental rounds were carried out and three different domains were applied. Each round had deferential teams working in the same domain. The experiments also involved the Unified Process (UP) to guiding the SDP and the Theory of Constraints (TOC) to identify and treat the restrictive elements found in the productive process. As results, the work presents a set of qualitative constraints subdivided into two groups: (1) Behavioral Constraints (BC), and (2) Technical Constraints (TC). The identification of these qualitative constraints allowed quantitative bottlenecks to be detected. The research also showed that bottlenecks are associated with certain tasks performed in the software development environment within a given domain. In general, these tasks are consuming resources, such as effort, time and human resources. This fact leads to the software product to a low quality due to the lack of completeness and correctness of the artifacts delivered to the end of the productive process.
... The study shows that the EVM methodology fits well into this multiple buffer control method and is able to accurately predict project problems along its progress. The authors give some advice how to best place the buffers in the project, and compare the well-known project buffers and feeding buffers of Goldratt (1997) with newly presented sub-network buffers and longest-path buffers (Lipke, 2015). ...
... Hence, the concept of allowable buffer consumption is nothing more than a tolerance limit, but this time based on simple analytical calculations instead of on rules-of-thumb and arbitrary values. However, the system differs from traditional buffering methods (Goldratt, 1997;Hu, Cui, Demeulemeester, & Bie, 2015) since the so-called buffered planned progress is calculated using EVM metrics, and does not simply rely on linear or arbitrary buffer consumption rules as often done. Computational experiments have shown that these analytical tolerance limits set on the buffer consumption show a slightly improved performance for project control compared to the traditional static thresholds for serial projects, but improve the efficiency of project control for project that have a more parallel structured network. ...
... The authors use the EVM tolerance limits at various points in the project network. More precisely, they introduce these multiple control points as buffers in the network based on the critical chain/buffer management methodology (Goldratt, 1997). They argue that the use of multiple control points results in a higher effort of control (since the project manager has to follow-up various metrics during the project progress), and they therefore compare various variants of buffer points for schedule control, and conclude that some of the methods with a low number of control points perform equally well than the systems with more control points. ...
Article
Monitoring the performance of projects in progress and controlling their expected outcome by taking corrective actions is a crucial task for any project manager. Project control systems are in use to quantify the project performance at a certain moment in time, and allow the project manager to predict the expected outcome if no action is taken. Consequently, these systems serve as mechanism that provide warning signals that tell the project manager when it is time to take corrective actions to bring the expected project outcome back on track. In order to trust these generated warning signals, the project manager has to set limits on the provide performance metrics that serve as thresholds for these actions. This paper gives an overview of different approaches discussed in the literature to control projects using such actions thresholds. First and foremost, the paper discusses three classes of actions thresholds,ranging from very easy-to-use rules-of-thumb to more advanced statistical project control methodologies. Each of these tools have been the subject to research studies, each of which aim at showing their power to predict project problems during its progress. In addition, the paper will emphasize the fundamental different between statistical project control using tolerance limits and statistical process control for projects. Finally, three different quality metrics to evaluate the performance of such control methods are presented and discussed.
... CPM and PERT project scheduling methods have remained relatively unchanged since its introduction in the 1950s, while CCPM was considered as an innovative breakthrough (Ghaffari & Emsley, 2015). Goldratt (1997) acknowledged that project costs were a function of project schedule performance. He emphasised that contingency (task) times were being wasted due to its stochastic allocation within project schedules; leading to an issue known as the student syndrome (Figure 12). ...
... In addition, the is more complex and may lead to new resource contentions (refer to problem provided by Rizzo (1999)). It is noteworthy that the precision of introducing feeding buffers is provided by Goldratt (1997). To date, there is no general optimization method for CCRCS due to its complexity. ...
... It is further divided into subcategories schemes. Two models are used as the main research categories, one is PERT project scheduling by Malcolm et al. in 1957(Malcolm, 1959) and the other CCPM by Goldratt (1997). Their related subcategories: ( ) optimistic, ( ) the most likely and ( ) pessimistic task time and expected project time is computed for the PERT and CCRCS respectively for the PM case study project. ...
Thesis
Scope This research case study focused on identifying the benefits of introducing the criticality index concept for selection of the critical chain project management (CCPM) using Monte-Carlo simulation, i.e. Improvements in the measurement of task time and the expected project time are addressed in preference to the accuracy of estimates. This research contested the CCPM normally performed, by modelling the theory for optimisation of projects (TOP1) using nuclear case study projects of South Africa. To support the identification of the benefits of introducing the criticality index concept for selection of the CCPM, the objectives of this study were (1) to present a TOP through simulation and (2) to validate the theory through an empirical study.
... Some of the other theories currently applicable to the AEC industry are: Theory of Constraints (Goldratt, 1997); Queuing theory (Gross and Harris, 1985); V-model (Forsberg and Mooz, 1998); and Transformation-Flow-Value generation model (Koskela, 2000). Goldratt (1997) introduces a five-step method to address system problems as a result of the constraints, which is applied on a continuous improvement basis. ...
... Some of the other theories currently applicable to the AEC industry are: Theory of Constraints (Goldratt, 1997); Queuing theory (Gross and Harris, 1985); V-model (Forsberg and Mooz, 1998); and Transformation-Flow-Value generation model (Koskela, 2000). Goldratt (1997) introduces a five-step method to address system problems as a result of the constraints, which is applied on a continuous improvement basis. The steps are: identify the system's constraint; exploit the constraint; adjust the setting of other activities to the constraint; alleviate the constraint; if the constraint is broken in any of the steps, go back to step one. ...
Article
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Theoretical developments in the Architectural Engineering and Construction (AEC) industry have been deficient, especially for the operations and use phase. The need for asset owners to understand the Building Information Modelling (BIM) process and to realise business value from BIM implementation cannot be over emphasised. This study investigates a BIM-based Asset Management (AM) system to examine how business value can be created for the asset owner. The BIM-based AM system is evaluated from the Transformation-Flow-Value (TFV) generation view to define the characteristics and functions. This is followed by the grounding of data to develop a novel explanatory theory through the development of conceptual categories. A qualitative research approach based on a grounded theory methodology is utilised to generate a proposition on how BIM can create value in an AM system. The study involves a five-stage research design using interviews and document analysis to inform the phenomenon of BIM business value creation in AM. The paper highlights that BIM business value generation in AM is dependent on three main categories, which are: development of the information requirements, creation of the information content and management of the information content. From the grounded data, the study finds that it is crucial for asset owners to develop their information requirements since the information requirements development category guides the data creation, data management and value generation. Furthermore, the development of a sound rationale that appropriately translates the organisational business objectives is critical to value generation. The paper studies how BIM can create business value in an AM system using a grounded theory methodology. The results show that the rationale for developing BIM-based information requirements determines the value that will be generated by the AM system. The key contribution of the paper is that it presents a novel theory for BIM-based AM. One of the contributions of this study is the demonstration of the application of grounded theory within the AEC industry. Also, the study demonstrates the relationships between concepts and how they emerge from the grounded data.
... On the other hand, not all researchers/practitioners recommend the use of milestones. According to Goldratt, and the critical chain project management (CCPM) concept [29][30], it is advisable to eliminate milestones, because their use may lead to delays in project implementation. In our work during the stage execution, activities from the next stage can be performed, thus avoiding waste of time when running a project with defined milestones. ...
... The experiments were run on a computer with a Intel Core I7, 3.0 GHz CPU and 8 GB RAM, using an application developed in C# in the Visual Studio.NET environment. For computations, 1,440 test instances from the PSPLIB [30] were used, from the The contractual milestone deadlines were determined based on the project deadline duedate from a PSPLIB test instance: ...
Article
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The paper analyses the problem of discounted cash flow maximising for the resource-constrained project scheduling from the project contractor’s perspective. Financial optimisation for the multi-stage project is considered. Cash outflows are the contactor’s expenses related to activity execution. Cash inflows are the client’s payments for the completed milestones. To solve the problem, the procedure of backward scheduling taking into account contractual milestones is proposed. The effectiveness of this procedure, as used to generate solutions for the simulated annealing algorithm, is verified with use of standard test instances with additionally defined cash flows and contractual milestones.
... The manufacturing world constantly follows new management ideas and emerging methodologies. The Theory of Constraints (TOC) (Goldratt, 1997;Goldratt & Cox, 1992) is not an especially new one, but to date, it has not been widely researched by scholars, particularly with respect to the peculiarities of its implementation. TOC tempts managers due to its simplicity, which can be summarised as follows: find a constraint of your system and improve the throughput of it, thereby improving the productivity of the entire system. ...
... TOC, which is also known as Goldratt's theory, is plainly elaborated and justified by its author with respect to the central idea (Goldratt, 1997;Goldratt & Cox, 1992;Goldratt, Schragenheim, & Ptak, 2000). There are also application proposals, such as managerial methodologies (Chowdhary, 2009;Cox & Schleier, 2010;Dettmer, 1998;Roser, Lorentzen, & Deuse, 2015;Scheinkopf, 1999). ...
Article
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Although the Theory of Constraints (TOC) is a widely known management concept, it warrants further research, particularly in terms of its application. The study investigates TOC implementation in a medium-scale manufacturing system with diverse products. The instrumental case study methodology is employed in this study, and the conceptual studies assess the case. The study helps to elucidate the methodology of TOC implementation in a manufacturing system. Instead of the five-step sequential approach that exploits constraints one after another, the cycles of system productivity target points are proposed, where each improvement cycle simultaneously considers several constraints. The proposed methodology is visualised, several implications and suggestions for constraint identification are provided, and a new method of bottleneck identification is elaborated in this study.
... Goldratt first introduced the possibilities of TOC within PM and specifically toward scheduling in the book Critical Chain when he defined the "critical chain" as the path that determines project duration (Goldratt, 1997). With the publication of this book, TOC transitioned from the factory floor to PM in 1997. ...
... Mathematics forms the foundations of FST and allows qualitative data to be used for creating semi-quantitative information via a linguistic scale. Goldratt's (1997) TOC emphasized that all systems have a limiting factor, or "bottleneck." As such, practitioners must endeavor to identify the bottleneck, then minimize (or eliminate) said factor. ...
... Accordingly, in recent years many researchers have stressed the importance of an explicit focus on resource management for developing an effective project schedule. Many authors consider a resource-focused scheduling approach proposed by Goldratt (1997) as a major breakthrough in the history of project management (Demeulemeester and Herroelen 2002). ...
... The Cut and Paste Method (C&PM): The C&PM method, initially proposed by Goldratt (1997), eliminates 50% of the activity duration as the safety time and then takes 50% of the summation of these safety times as the buffer size. The C&PM method brings the advantage of simplicity. ...
Article
The methods presently used for buffer sizing of Critical Chain Project Management (CCPM) have lagged far behind capturing the stochastic nature of resource acquisition in real-world projects. The work described herein represents a new step towards the sizing of buffers for CCPM by developing a probabilistic measure obtained through a reliability analysis of project resources. The proposed method treats the resource availability as a random variable in project scheduling, meaning that each resource has a distribution of possible values of availability. In this method, buffer size is determined by assigning a scaling factor to the standard deviation of a chain. This scaling factor is the function of the reliability of available resources assigned to the chain activities, taking into account the likelihood of timely completion of the chain given the reliability of each individual resource. Sensitivity analysis, as well as the comparison of the proposed method with the conventional buffer sizing methods, reveal the effectiveness of the new method.
... When E. Goldratt proposed that the project buffer (PB) and feeding buffers (FB) be placed in the structure of network schedules [1], many authors attempted to develop a method for determining their size [2][3][4]. This was mainly due to the fact that Goldratt in his book gave only general assumptions, without indicating the exact method of their calculation. ...
Article
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The literature offers numerous proposals for calculating the project buffer, located at the end of the critical chain. However, the structure of construction schedules, often consisting of several dozen or several hundred tasks, requires planning a larger number of buffers, also located on the critical chain. The article proposes an original method of dividing the duration of one buffer located at the end of a protected chain (e.g. a project buffer) into several auxiliary buffers, protecting individual fragments of this path. The basis of the algorithm that calculates their size is to take into account the robust of protected task paths before the deadline for their completion is disrupted. As a measure of robust understood in this way, the ratio of the buffer size to the sum of the variance of the task duration of the protected draft was applied. The criterion of searching for the optimal time division into several buffers was to maximize the minimum robust of all analyzed paths. The application of the proposed optimization model is illustrated on the example of a specific construction schedule.
... Because the contract signed by the contractor obliged him to perform the works in 229 days, the schedule including time reserves related to the occurrence of potential threats and 250 days schedule had to be shortened. This was done by the method proposed by Goldratt [10], thus shortening the initial times of tasks and inserting time buffers. At the beginning, the times of most tasks have been shortened. ...
Article
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In article authors focus on preparation of construction works schedule for high pressure gas pipeline in urbanized area and implementation of risk analysis in estimation of realistic completion date. In the first step, the pipeline was divided into couple of sections with different construction methods. During evaluation open cut methods, HDD and microtunneling methods were verified and for every approach specific types of risk were identified. Since number of potential risks was significant authors decided to apply the method for ranking the risks and introducing most important potential complications in the construction schedule. After risk identification authors prepared set of impact categories, varying for negligible few days delays to disastrous three months or more delays. Moreover for potential risks a list of probabilities were elaborated to described risk is plausible to happen several times during project execution or is rather likely to occur every couple of similar projects. Combination of sets of possible impacts and sets of probabilities resulted in a project specific risk matrix. Risk matrix was the first tool used for ranking of all risks, especially when regions of intolerable risks and risks requiring mitigation plan were drawn in the matrix. Based on professional literature, and their own experience for every potential risk, authors estimated the risk level. Knowing this in the next step all risks were sorted according to decreasing value of risk level and for risks within intolerable area or within area requiring emergency back-up plan. Authors verified if those plausible risks indeed require a schedule reserve or some other solution may be applied. If schedule reserve was a reasonable solution the relevant additional construction time was estimated, having in mind the schedule impact level of reviewed risk. In the end construction schedule was prepared, which includes the risk analysis for all construction methods.
... The use of indexes and methods are commonplace in project management as a means of dealing with uncertainty (de Koning, 2013;Hedeman et al., 2013). PERT (Malcolm et al., 1959), GERT (Pritsker & Whitehou, 1966), EVA (Haugan, 2002), and Critical Chain (Goldratt, 1997) are helping the project manager with the time, schedule and value issues of a project. The point is that these evaluation methods of projects are designed to be helpful during project execution and are not designed to be helpful for the go/no-go decision. ...
Thesis
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The goal of this thesis was to establish whether an index of uncertainty in projects based on project value and estimates results in more objective information and is prognosticative for the go/no-go decision of a project (Atkinson, Crawford, & Ward, 2006). The project management profession has a problem; common project management practice does not address many fundamental sources of uncertainty, particularly in 'soft' projects where flexibility and tolerance of vagueness are necessary (Atkinson et al., 2006). The main research question was therefore: What is the prognosticative value of an index of project uncertainty for informing the go/no-go decision of projects? Better information leads to better decisions (Davis & Metcalf, 2014). Accordingly, an index summarising these sources of uncertainty may enhance the information provided by business cases and other means of selecting projects in organisations before executing these projects. Because there are no indexes available that provide information about the sources of uncertainty before the project go/no-go decision, an index was created as a research artefact. This index is based on literature findings. In order to present some evidence about prognostication of the index that was created, four tests were executed: correlation, predictive value, Brier score method test, and comparison with the Project Evaluation Review Technique (PERT). Using microwork sites and test design, participants were recruited from all over the world. The index used used for testing is the research artefact index developed. It was found that an index helps to gain insight into some of the sources of uncertainty in projects by means of providing more objective information about estimates and perceived value for the go/no-go decision of projects. Four recommendations for future research were established based on the findings: First, the science of estimates is based on research with mostly students. Therefore the project management profession may benefit from replicating the findings with other cohorts. The second recommendation is that the research artefact index may be enhanced by incorporating multiple stakeholder views. The third recommendation is including project complexity and the forth recommendation is that case studies are needed to increase the research artefact index validity.
... Here, buffering departed from its narrow meaning of 'slack' time or money, as described by e.g. Gutierrez et al. (1991), Goldratt (1997) or PMI (2013, p. 533), coming closer to 'excess capacity' described by Kalra et al. (2014, p. 21) or 'margins' as defined by Eckert, Earl, Lebjioui, and Isaksson (2013, p. 41) as "the extent to which a parameter value exceeds what it needs to meet its functional requirements regardless of the motivation for which the margin was included". ...
Article
Uncertainty exists when action must be taken without knowledge of the possible outcomes and the probabilities of their occurrence. This is evidently the case in many real-life projects. Recent literature calls such projects ‘exploratory’, i.e. their goals and the means to attain them are uncertain at the outset. This presents a challenge to traditional project management—working from known means towards known ends—and may explain high rates of project failure. Nonetheless, prescriptions for managing exploratory projects remain situational and fragmented across schools of thought. The aim of this paper is to identify the repertoire of approaches adopted in practice by managers of such projects, and to outline the theoretical underpinnings of exploratory project management. Through the lens of resilience theory, we investigate the approaches adopted by 19 managers of exploratory projects across 14 Danish firms. The paper's contribution is two-fold: First, we present a consistent repertoire of eleven generalizable approaches to managing exploratory projects across a range of industries and project types. Second, outlining shared theoretical underpinnings, we explain the repertoire as preparatory, (pre-action), attemptive (during action) and responsive (post outcome) efforts to achieve resistance to and recoverability from unexpected events. Fundamentally, we argue for shifting focus from ‘what we know’ to ‘how we act’ when faced with exploratory projects.
... Light-footed reasoning and techniques are not a disengaged marvel, however. As per [2] a few books covering distinctive administration plans and hypotheses have been composed that identifies with and addresses the thoughts fundamental lithe venture the executives rehearse, for example, Critical Chain Theory [3] and Lean Production [4]. ...
Article
There are thinks about demonstrating what occurs if coordinated groups are brought into a non-light-footed association, for example higher overhead expenses and the need of a comprehension of deft techniques even outside the groups. This contextual analysis demonstrates a case of work inspirational perspectives that may surface when a dexterous group exists amidst a progressively conventional structure. This contextual investigation was directed at a vehicle producer in Sweden, comprising of an unstructured meeting with the Scrum Master and a semi-organized center gathering. The outcomes demonstrate that the groups felt that the criticism from the encompassing association was unsynchronized bringing about them not feeling acknowledged while conveying their work. Besides, they felt baffled when dealing with non-dexterous groups after have been taking a shot at coordinated ones. This investigation reasons that there were work inspirational effects of fitting a nimble group into a non-spry encompassing association, and in this way this may likewise be valid for different associations.
... Different methodologies have emerged for effectively planning and controlling a project. The Critical Chain Project Management (CCPM) [1] focuses on eliminating the floats from activities and reallocating them into strategic positions on the critical chain. These time positions are known as "buffers". ...
... After a scheduling simulation, Primavera Risk Analysis can produce the expected completion date of various probabilities. However, in terms of reliability, it is said that the probability of project completion at 80~90% is realistic [36]. Therefore, the research team determined to use the median value of 85%. ...
Article
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Korean oil and gas contractors have recently incurred significant losses due to improper engineering performance on EPC (engineering procurement and construction) projects in overseas markets. Several previous studies have verified the significant impact engineering has on EPC construction cost and project lifecycle. However, no literature has studied the time impact engineering has on EPC projects, representing a gap in the existing body of knowledge. To fill this gap, a Monte Carlo simulation was performed with the Pertmaster, Primavera risk analysis software for three sample onshore oil and gas projects. From said simulation of all major EPC critical activities, the authors found that the engineering phase is up to 10 times as impactful as the procurement and construction phases on the overall schedule duration. In assessing the engineering activities, the authors found the piping design activities to have the greatest impact on the overall schedule performance. Using these findings, the authors present a design schedule management process which minimizes the delays of project completion in EPC projects. Said process includes the following six steps: (1) Milestone management, (2) drawing status management, (3) productivity management of engineering, (4) interface management, (5) management of major vendor documents, and (6) work front management. The findings of this paper add to the body of knowledge by confirming the design phase to be the most impactful on the overall project schedule success. Furthermore, the presented design schedule management will aid industry with successfully executing the design phase in a timely manner, including examples from case study projects for a greater understanding.
... The capacity to make a clear distinction between the tasks, the knowledge of the respective field, the problems solving method, as well as the integration of a well structured conceptual model, stand for the basis required for the development of such an Intelligent System, by taking into account the uniqueness of each type of planner. The scheduling intelligent system called "PManager" and presented in this article comprises a new method of present interest in scheduling called "Time Buffer" conceived for shortening the time required by the project achievement on the basis of the time reserve assigned to the Critical Path, which is calculated according to the following rule: there is calculated the sum of the safety estimations obtained through the differences between the pessimistic and optimistic periods (estimated according to PERT method) of the critical tasks, and then it is reduced to a half [6], the technique of time buffer obtaining being inspired from the Theory of Constraints developed by Elyahu M. Goldratt [1]. ...
Article
The paper presents a scheduling intelligent system intended for the project management and for the operation management as well, having integrated a planner time buffer method combined with the PERT (Programme Evaluation and Review Technique) method which can drastically short the planned time. The system also adjusts if necessary the duration for the un-expecting situations during the evolution of the planner recalculating the probability to reach the deadline. The system is developed with a friendly graphical interface, which guide the user during the progress of the project providing warnings and suggestions for adjusting in real time the planner. Once the scheduling intelligent system is launched in progress, its functions are combined at the different levels, depending of the user needs. The base functions of the system are: planning, diagnosis, supervising and forecast. A real implementation is showed as a study case, is related to a software development planner.
... Project teams are free to choose appropriate methods to achieve project goals. The method attempts to take into account the impact of external factors on projects (Goldratt, 1997;Leach, 2014). In a quantitative manner, this impact is taken into account in the Reference Class Forecasting Method (RCFM) (Kahneman, 2011). ...
Article
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Forecasting Method (RCFM) developed by Kahneman and Tversky for planning and decisionmakingunder uncertainty. Project plans are usually prepared on the basis of detailed calculationsand arrangements according to selected project management methodology. Undertakings that areplanned in this manner often fail and do not achieve their goals. However, the American PlanningAssociation recommends using the RCFM as an additional method. The article presents four groupsof projects implemented by a chemical industry company over four years. A few of the projects wereaccomplished according to the plan in terms of triple constraint i.e. time, cost, and scope. The costaspect was taken into account in the paper. During the study, the planned and implemented costsof 222 projects were analysed. On the basis of the distribution of cost overruns, according to RCFM,new patterns of planned costs were prepared. The Reference Class Forecasting Method, which waseffective for large homogeneous projects turned out to be completely useless for various projectsimplemented by the chemical company.
... Among the first efforts to produce robust schedules we find [40] who introduces the concept of temporal protection, which extends the duration of activities based on the uncertainty statistics of the resources used for their execution. Later, one of the most popular approaches was Critical Chain Scheduling/Buffer Management (CC/BM) which builds a baseline schedule using aggressive median or average activity duration estimates as presented in [41]. In [42] they propose improvements of the temporal protection technique with their time window slack and focused time window slack approaches which do not include slack into activity duration, but rather explicitly compute available slack time per activity in solution schedules. ...
Chapter
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Companies invest countless hours in planning project execution because it is a crucial component for their growth. However, regardless of all the considerations taken in the planning stage, uncertainty inherent to project execution leads to schedule disruptions, and even renders projects unfeasible. There is a vast amount of studies for generating baseline (predictive) schedules, yet, the literature regarding reactive scheduling for the Multi-Mode Resource Constrained Project Scheduling Problem (MRCPSP) is scant with only two previous studies found at the time of writing. In contrast, schedule disruption management has been thoroughly studied in the mass production environment, and regardless of the difficulties encountered, they will almost certainly be required to meet the levels planned. With this in mind, this study proposes an integrative (proactive and reactive) scheduling framework that uses the experience and methodologies developed in the production scheduling environment and apply it to the MRCPSP. The purpose of this framework is to be used on further empirical research.
... • No consideran que los proyectos los hacen personas. Goldratt, E. M. (1997) problema; posteriormente la expresión se generaliza a "calidad incorporada" ("built-in-quality"). Kiichiro Toyoda: hijo del anterior, fundó la empresa de automóviles basándose en la que heredó de su padre e introdujo un par de conceptos fundamentales en el sistema: • Produktionstakt: Importado de la Alemania de la pre-guerra y que posteriormente se conoció como "takt time". Ritmo constante de producción según la demanda. ...
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... Additionally, where there were no hard deadlines, the finish date was often postponed. This behaviour echoes the 'student syndrome' as described in TOC literature (Goldratt, 1997;Leach, 1999). ...
Article
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Agile project management methods such as Scrum are being used increasingly in a wide range of contexts, including the public sector. This paper reports on a policy development project within a New Zealand government agency, which experimented with Scrum. Data collected from multiple semi-structured interviews and project documents were analysed using Theory of Constraints Thinking Processes (TP) tools, to understand the cause and effect relationships between a project’s variables and its outcomes. The TP tools were particularly powerful for identifying conditions assumed by Scrum which were not true in our case study, relating to the customer’s role and the nature of project deliverables. The TP tools were also used to analyse the project manager’s adaptation of Scrum to accommodate these specific requirements of this project. The case demonstrates that policy development shares standard project management concerns and would benefit from being managed as a project.
... A lot of analysis and proposed models can be found aiming at proofing the schedule from delays. Goldratt ideas [15] are being developed [16], [17]. Constrained, by the renewable resources, schedules are being optimized [18], [19], [20]. ...
Article
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The effects of the delay in construction contract execution are always negative for every party being involved. Cancelling the delays of the time schedule means the use of more production means that it was planned. It creates an additional cost. If the delays of the schedule are not cancelled, the contractor suffers from the cost increase. The penalties arisen from not keeping the milestones or the completion date are expected too. There is a trade-off: cancelling delays spending additional money now (during the contract execution) or executing a delayed contract till its end awaiting for its final settlement (showing the cost increase) and possible penalties. There is no one, correct answer how to manage a delayed construction project. There is a natural unwillingness to spend money over the budget. Nevertheless, the delayed completion date can cause much higher contractor’s expenses, than cancelling delays during the contract execution. The decisions made by the project manager depend on various factors discussed in the paper. A delay concerning the single task increases the cost of its execution at a different level. The same, the level of influence of delaying a single task, influences the completion date with varied strength. These influences depend on the location of the task in a net model – the base of a schedule. The tasks located on the critical path – defined in the Critical Path Method – should be of the special care. However, delays on not critical tasks can also break the budget and the planned completion date. The nature of delay is important as well. Lowered productivity of a workers’ brigade can make the execution of the task longer, the same as forced breaks in their efficient work. The reaction of a site manager to such causes of delay should be different, as the origin of the delays is different. The impact of the delay noticed on the single task is discussed in the paper and possible reaction (varied on the type of a delay and a task location too) are proposed. The proposed solutions aiming at cost minimizing considering the total expenses spent by a contractor and possible penalties in case of the delayed completion date of a construction contract.
... Buffer management approaches are a class of project resource management, which is related to uncertainty and Critical Chain [31]. Although, the uncertainty forces a centralized approach, resource allocation should be organized in a decentralized way in a multi-agent approach. ...
Article
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Propagating crowdsourcing services via a wireless network can be an appropriate solution to using the potential of crowds in crisis management processes. The present study aimed to deploy crowdsourcing services properly to spatial urgent requests. Composing such atomic services can conquer sophisticated crisis management. In addition, the conducted propagated services guide people through crisis fields and allow managers to use crowd potential appropriately. The use of such services requires a suitable automated allocation method, along with a proper approach to arranging the sequence of propagating services. The solution uses a mathematical framework in the context of a GIS (Geospatial Information System) in order to construct an allocation approach. Solution elements are set out in a multi-agent environment structure, which simulate disaster field objects. Agents which are dynamically linked to objects in a crisis field, interact with each other in a competitive environment, and the results in forming crowdsourcing services are used to guide crowds in the crisis field via the crowdsourcing services. The present solution was implemented through a proper data schema in a powerful geodatabase, along with various users with specialized interfaces. Finally, a solution and crowdsourcing service was tested in the context of a GIS in the 2019 Aqala flood disaster in Iran and other complement scenarios. The allocating performance and operation of other system elements were acceptable and reduced indicators, such as rescuer fatigue and delay time. Crowdsourcing service was positioned well in the solution and provided good performance among the elements of the Geospatial Information System. View Full-Text
... With a view to reduce such project inefficiencies, researchers in the fields of project management and project controls have developed various metrics, indicators, and tools to enhance both progress measurement and performance assessment in construction projects (Orgut et al. 2015(Orgut et al. , 2016. Some widely used methods include earned value management (Fleming and Koppelman 2000;Kim et al. 2016;Kim and Pinto 2018), earned schedule management (Lipke 2003(Lipke , 2009Hammad et al. 2018), earned duration (Khamooshi and Golafshani 2014;Khamooshi and Abdi 2017), and critical chain management (Goldratt 1997;Leach 2000;Ma et al. 2015); each of these methods was developed to overcome the limitations of the previous models. As projects have become larger and more complex (Bosch-Rekveldt et al. 2011;Luo et al. 2017), more advanced approaches, such as system-of-systems modeling (Zhu et al. 2014) and metanetwork analysis (Zhu and Mostafavi 2017), have been proposed for assessing performance efficiency of construction projects. ...
Article
A lack of consistent, reliable, and objective metrics and indicators for project controls poses major challenges for effectively measuring project progress and performance in the construction industry. Often, project managers are misled in their perceptions of project performance until the project nears its end. This lack of accurate project progress and performance information is a major issue that causes performance shortcomings and resource shortfalls. This study investigated critical factors for improving the reliability of project control systems throughout the construction project life cycle. Through conducting a survey and 10 in-depth case studies, this research identified 15 critical reliability improvement factors and 85 indicators with specific application timing and milestones. This robust framework for improving the reliability of project controls throughout the life cycle of a project was then validated by a panel of experts. The results of this study address an important gap related to the understanding of the key factors and indicators that contribute to the reliability of project control metrics and methods. Findings of this research may provide construction industry stakeholders with a tool to significantly improve the reliability of project progress and performance assessment practices.
... Due to the inherent nature of the construction industry, project managers must deal with different types of risk and uncertainty. As most of the project scheduling literature suggests the causes of such project delays are failures to implement one or more aspects of the existing project system, Goldratt (1997) observed project delay from the standpoint of the Theory of Constraints (TOC). He concluded that most project delay stems from improper management of uncertainty. ...
Article
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Uncertainty is one of the main parts of the project management environment that can strongly affect the project objectives and cause unpredictable delays. This study presents a multi-objective optimization approach for constructing resilient project schedules under resource constraints to cope with uncertain activity durations. In this paper, the concept of resilient project scheduling is defined to measure the ability of schedules to deal with duration disruption. Since the direct evaluation of resiliency is computationally complicated and time-consuming, a new surrogate resilience measure is introduced. The proposed resiliency criteria measure the floating of activities and the risks associated with the completion of the project. Furthermore, a new model based on a combination of time buffer and float allocation approach is developed. To extend existing project scheduling models with uncertainty, general precedence relationships between activities have been considered. To validate the proposed approach, the construction project of a combined cycle power plant is used as a case study. Due to a large number of project activities in this case study, the non-dominated sorting genetic algorithm (NSGA II) has been used to solve the problem. The results of solving the mathematical model using the proposed method are assessed through extensive simulation experiments and compared with those of the baseline schedule. The results show that by taking the proposed resiliency measure and the optimal allocation of buffer time to activities, the project completed at the same duration with higher reliability.
... Kamienie milowe są istotnym elementem planowania prac w rzeczywistych projektach, mimo krytycznej oceny ich wprowadzania w popularnej aktualnie metodzie planowania projektów CCPM (ang. Critical Chain Project Management) (Goldratt, 1997). Kamienie milowe ułatwiają ocenę stopnia realizacji prac projektowych. ...
Article
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Streszczenie: W pracy przedstawiony jest problem harmonogramowania wieloetapowego projektu z ograniczonymi zasobami z maksymalizacją zdyskontowanych przepływów pieniężnych z perspektywy wykonawcy z uwzględnieniem interesów klienta. Jako ujemne przepływy finansowe rozpatrywane są wydatki wykonawcy związane z realizacją czynności. Dodatnimi przepływami pieniężnymi są etapowe płatności klienta, wykonywane w wyso-kościach równych niezbędnym wydatkom wykonawcy ponoszonym w następnym etapie projektu. Wykonawca nie może realizować czynności, jeśli nie otrzyma środków finansowych od klienta. W pracy zilustrowany jest proponowany sposób ustalania etapowych rozliczeń między klientem a wykonawcą. Następnie zaprezentowana jest metoda generowania rozwiązań dedykowanych dla analizowanego problemu: technika justyfikacji uwzględniająca etapy projektu. Słowa kluczowe: harmonogramowanie projektu z ograniczonymi zasobami i kapitałem, maksymalizacja zdyskontowanych przepływów pieniężnych, kamienie milowe, płatności progresywne, justyfikacja. Abstract: The paper presents the problem of scheduling a multi-stage project with limited resources with the maximization of discounted cash flows from the perspective of the contractor, taking into account the client's interests. The contractor's expenses related to the execution of activities are considered as negative cash flows. The positive cash flows are staged client payments, made in amounts equal to the necessary expenses of the contractor incurred in the next stage of the project. The contractor may not execute activities if he does not receive funds from the client. The paper illustrates the proposed method of establishing staged settlements between the client and the contractor. Next, the method of generating solutions dedicated to the analyzed problem is presented: the justification technique taking into account the project stages.
... Critical chain project management (CCPM) has attracted extensive attention in both business and academic fields. The fundamental principle of CCPM is to use critical chain instead of traditional critical path, insert a project buffer at the end of project and insert feeding buffers wherever non-critical chains join critical chain to protect project completed on time (Goldratt 1997). Due to the complexity of a project, inserting feeding buffers may cause a conflict, such as precedence conflict or resource conflict, which can be solved by rescheduling. ...
... This algorithm is based on the Critical Chain and Buffer Management Method CC/BM (Goldratt 1997) related to the Theory of Constraints (TOC). The critical chain is defined as a set of the activities that determine the total time of the project completion, taking into consideration the sequential relationships and the resource constraints. ...
Article
Predictive scheduling is a new approach used in production planning. The aim of this approach is to develop robust schedules and solutions that are able to absorb disruptions during the schedule execution. In this paper, we present algorithms of predictive scheduling for the Resource-Constrained Project Scheduling Problem (RCPSP), with defined dates of selected activities.
... dwa lub więcej działań mogły być przypisane do tego samego zasobu w tym samym przedziale czasowym). Ten problem został wyeliminowany w opracowanej przez E. Goldratta metodzie łańcucha krytycznego CCPM (Critical Chain Project Management) (Goldratt, 1997; Cox, Schleier, 2010, s. 13-44). Łańcuch krytyczny jest tworzony przez przekształcenie ścieżki krytycznej w wyniku wyeliminowania konfliktów zasobowych. ...
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W 1896 roku Karol Adamiecki wprowadził do praktyki zarządzania wykresy organizacji pracy, które nazwał harmonogramami. Powyższe rozwiązanie dało początek rozwojowi metod ukierunkowanych na racjonalizację organizowania procesów wytwarzania. W opracowaniu zostały omówione następujące grupy metod organizowania procesów pracy w czasie: metody harmonogramowania produkcji, teoria kolejek i reguły priorytetu, metody planowania projektów: diagramy sieciowe i metoda łańcucha krytycznego, karty kanban oraz inne warianty systemu pull, a także teoria ograniczeń oraz jej narzędzia: werbel-bufor-lina. W podsumowaniu zwrócono uwaga na nieustającą potrzebę koordynowania procesów w czasie, krótki "żywot" harmonogramu jako wzorcowego planu ze względu na ogólną i specjalną losowość procesów, przejście z podejścia push na pull oraz współcześnie stosowane metody bieżącego koordynowania procesów w czasie.
... In case the prior approach is not feasible, the project requirement may be altered in order to manage with the recent situation. In dealing with project uncertainty, Goldratt [4] proposed an implementation of the Theory of Constraints called Critical Chain Project Management (CCPM). CPPM uses two type of buffer namely project buffer and feeding buffer, both to protect the critical chain from disruptions. ...
Conference Paper
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Engineering-To-Order (ETO) is a production approach where manufacturers design, engineer, and assemble a unique product based on specific customer requirements. In this type of operation, manufacturers are faced with many uncertainties in the supply chain and design process, which often lead to unreliable delivery time and high total cost. This paper proposes a project management approach to cope with the uncertainties in the ETO supply chain by allocating some buffer times within the supply chain network. Particle Swarm Optimization (PSO) is used to find the optimal configuration of the buffer time within the supply chain. The result shows that the buffer time optimization method can help manufacturers to keep a high level of on-time delivery performance (95%) while keeping the total cost minimum.
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Rework risks caused by information flow interactions have become a major challenge in project scheduling. To deal with this challenge, we propose a model integrating the critical chain project management method, design structure matrix method, and max-plus method. Our model uses a start-to-start relationship of activities instead of the traditional finish-to-start relationship, which also allows overlaps between activities. We improve the accuracy of the rework safety time in two ways: (1) the overall overlapping effect is taken into consideration when calculating the rework time of an activity arising from the information flow interaction of its multiple predecessors overlapped with it; (2) the rework time arising from activity overlaps, the first rework time, and the second rework time are calculated as components of the rework safety time in our model, while the last one is ignored in traditional methods. Furthermore, the accuracy of time buffers is improved based on the improved rework safety time. Finally, we design the max-plus method to generate project schedules and appropriately sized time buffers. The empirical results show that the project schedule generated by the proposed method has a higher on-time completion probability, as well as more appropriately sized project buffers.
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Although South Africa possesses more than 80% of the world’s platinum reserves, its reputation for reliability in supplying platinum to global markets is under threat. This is due to the 49% decrease in output per worker (1999–2014), while the domestic costs have risen by more than 10% annually for the past 5 years. In addition, the continued decline in the commodity price by 38.3% (2012–2016) has resulted in a significant portion of the sector producing at a loss in 2015. The Chamber of Mines (now the Minerals Council of South Africa) has suggested that solutions to improve productivity and reduce cost pressures are required. This research aims to provide operational excellence through the application of event chain project management (ECPM) to improve productivity and reduce operational costs. A case study was used to carry out research in platinum mines, with data collected using a motion-time study to measure the current efficiency of operations in each mining stope through actual activity durations. The results indicate that through the application of the event chain project management methodology, risks affecting the mining stope schedule can be managed, the efficiency of operations was improved by reducing the time spent on each activity, productivity was increased by shortening the project duration, and operational costs were reduced in the process.
Conference Paper
This paper discusses the Lean methodology of Va- lue Stream Mapping (VSM) in a handicraft enterprise with Make to order environment. Within a case study of a wood craft com- pany, the method is applied and improved. The purpose of VSM is to initialize the lean transformation and to understand the va- lue streams of a company as a basis for further improvements. The paper explores the current literature about VSM and also discusses the specific characteristics of a MTO environment and its limitations regarding the application of the current VSM me- thodology. Based on this, an adapted VSM procedure with a spe- cial focus on MTO or ETO small and medium craft enterprises is presented. This paper contains the steps to flow to build a current VSM in this environment with a new formulation to calculate the metrics point such as cycle times and setup times.
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Considering that the mission of the project organization management is to create a commitment to the timetable, which prevents project delays and increases associated costs, and accept the fact that the delay in the completion time of the project results in the non-economization of the project, Therefore, the necessity of using proper planning and control methods seems necessary. One of the new methods used in project planning and control, which today focuses on many researchers, is the critical chain management method. In this research, multi-project scheduling with resource constraint in the critical-chain model has been investigated. In general, RCMPSP seeks to find the right sequence for project activities, so that the constraints of the priority of the project network and the various types of resource constraints in the project are met simultaneously. To this end, a multi-objective optimization model has been developed to solve this problem, with its stated objectives, the completion time of the entire project, the cost of the overall project implementation, and the quality of the implementation of the project activities. Also, the critical chain approach, as a new method of project management, has been used for project scheduling and particle swarm optimization algorithm for solving proposed model of this research.
Chapter
The companies will become the center of business with the Industry 4.0 revolution implementing IT integration, cloud-based applications, data management, rapid decision-making operations, etc. These transformations can be realized with an effective project management, and project managers have a big role in this context. The quality of the software is very important for Industry 4.0, given that it can be as strong as the weakest link in a chain. Collaboration between producers and customers plays an increasingly important role in software processes where agile applications have recently been proposed. In this chapter, for the success of the project manager, Theory of Constraints is applied to remove the problems that may be encountered with the implementation of the agile methods during identifying the problem and determining its solution. The proposed solutions to uncover the reasons not reaching the targeted quality and removing the obstacles will be a guide for software project managers.
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Construction supply chains encompass the Flows of Materials, Cash, Labor, Information, Plant, Equipment and Temporary Works that originate from a variety of different parties. In Kenya, several road construction projects have had time overruns in their completion, (KeNHA 2014). This research was thus centered on establishing the Influence of Information flow management on the Supply Chain Performance and subsequently the Lead Time of Road Construction Projects in Kenya. The study was guided by the following specific objectives: First, to establish the influence of Information Flow and Road Construction Projects' Lead Time in Kenya. Secondly, to establish the relationship between Information Flow, supply chain performance and Lead Time of Road Construction Projects in Kenya. This study was anchored on Simulation Theory and Goldrat's Theory of Constraints (TOC). Preliminary investigations was carried out by visiting two road construction projects over a period of two weeks to gain an understanding of the ways in which information flow management impacted on supply chain performance & subsequently on lead time of road construction project. This was followed by the main cross sectional survey designed to collect the required data. Stratified purposive sampling was used to select the sample size. The study comprised of a target population of 116 and a sample size of 90 respondents determined by Yaro Yamane Formula (1967). Data was collected using structured questionnaires and interview guides whose reliability and validity were tested at the index of 0.70. The Cronbach's Alpha coefficient was used to measure the reliability on a 5-point Likert Scale for multiple items. Validation of the questionnaire was done by construction and supply chain specialist while content validation was done by pilot survey. Data analysis was done by multiple regression analysis and content analysis. The hypotheses were tested using Pearson chi-square test of independence at a significance level of 0.05. The findings show that supply chain performance had a significant moderating effect on the relationship between material flow management and lead time of road construction projects (F=15.311, R² = 0.483, Sig=0.000 at α=0.05). The study therefore concludes that supply chain performance has a moderating effect on the relationship between information flow management and lead time of road construction projects in Kenya with this predictor model: P t = 2.05+0.622X 1-0.53Z 5 + 0.92Z 6-0.115Z 7 + 0.2Z 8 + 1.113. Contractors should acquire and establish a sofware that would help mange information flow in each and every road project. The findings provide a practical and useful tool for construction project managers to audit construction information flow management with an effort to deliver timely projects. KeNHA would also be able to estimate road construction projects lead times besides the provision of an information flow-lead time model for scholars.
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Construction supply chains encompass the Flows of Materials, Cash, Labor, Information, Plant, Equipment and Temporary Works that originate from a variety of different parties. In Kenya, several road construction projects have had time overruns in their completion, (KeNHA 2014). This research was thus centered on establishing the influence of material flow management on the supply chain performance and subsequently the lead time of road construction projects in Kenya. The study was guided by the following specific objectives: First, to establish the influence of material flow and road construction projects' lead time in Kenya. Secondly, to establish the relationship between material flows, supply chain performance and lead time of road construction projects in Kenya. This study was anchored on Simulation Theory and Goldrat's Theory of Constraints (TOC). Preliminary investigations was carried out by visiting two road construction projects over a period of two weeks to gain an understanding of the ways in which material flow management impacted on supply chain performance & subsequently on lead time of road construction project. This was followed by the main cross sectional survey designed to collect the required data. Stratified purposive sampling was used to select the sample size. The study comprised of a target population of 116 and a sample size of 90 respondents determined by Yaro Yamane Formula (1967). Data was collected using structured questionnaires and interview guides whose reliability and validity were tested at the index of 0.70. The Cronbach's Alpha coefficient was used to measure the reliability on a 5-point Likert Scale for multiple items. Validation of the questionnaire was done by construction and supply chain specialist while content validation was done by pilot survey. Data analysis was done by multiple regression analysis and content analysis. The hypotheses were tested using Pearson chi-square test of independence at a significance level of 0.05. The findings show that supply chain performance had a significant moderating effect on the relationship between material flow management and lead time of road construction projects (R 2 =0.143, F (1, 87) 2.739, p=0.024, α=0.05). The study concluded that supply chain performance has a moderating effect on the relationship between material flow management and lead time of road construction projects with a predictor model (P t = 1.488-0.133 X 1 + 0.123Z 5 + 0.382Z 6-0.053Z 7 + 0.345Z 8 + 1.518). Contractors should acquire an inventory management sofware to manage material demand and supply. The findings provide a practical and useful tool for construction project managers to audit construction material flow management with an effort to deliver timely projects. KeNHA would also be able to estimate road construction project lead times besides the provision of a material flow-lead time model for scholars.
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Construction supply chains encompass the Flows of Materials, Cash, Labor, Information, Plant, Equipment and Temporary Works that originate from a variety of different parties. In Kenya, several road construction projects have had time overruns in their completion, (KeNHA 2014). This research was thus centered on establishing the Influence of Information flow management on the Supply Chain Performance and subsequently the Lead Time of Road Construction Projects in Kenya. The study was guided by the following specific objectives: First, to establish the influence of Information Flow and Road Construction Projects'Lead Time in Kenya. Secondly, to establish the relationship between Information Flow, supply chain performance and Lead Time of Road Construction Projects in Kenya. This study was anchored on Simulation Theory and Goldrat's Theory of Constraints (TOC). Preliminary investigations was carried out by visiting two road construction projects over a period of two weeks to gain an understanding of the ways in which information flow management impacted on supply chain performance & subsequently on lead time of road construction project. This was followed by the main cross sectional survey designed to collect the required data. Stratified purposive sampling was used to select the sample size. The study comprised of a target population of 116 and a sample size of 90 respondents determined by Yaro Yamane Formula (1967). Data was collected using structured questionnaires and interview guides whose reliability and validity were tested at the index of 0.70. The Cronbach's Alpha coefficient was used to measure the reliability on a 5-point Likert Scale for multiple items. Validation of the questionnaire was done by construction and supply chain specialist while content validation was done by pilot survey. Data analysis was done by multiple regression analysis and content analysis. The hypotheses were tested using Pearson chi-square test of independence at a significance level of 0.05. The findings show that supply chain performance had a significant moderating effect on the relationship between material flow management and lead time of road construction projects (F=15.311, R² = 0.483, Sig=0.000 at α=0.05). The study therefore concludes that supply chain performance has a statistically significant moderating effect on the relationship between information flow management and lead time of road construction projects in Kenya with this predictor model: Pt = 2.051-0.622X1-0.36Z5-0.343Z6-0.391Z7-0.371Z8. Contractors should acquire and establish a software that would help manage information flow in each and every road project. The findings provide a practical and useful tool for construction project managers to audit construction information flow management with an effort to deliver timely projects. KeNHA would also be able to estimate road construction projects lead times besides the provision of an information flow-lead-time model for scholars.
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Full-text available
Construction supply chains encompass the Flows of Materials, Cash, Labor, Information, Plant, Equipment and Temporary Works that originate from a variety of different parties. In Kenya, several road construction projects have had time overruns in their completion, (KeNHA 2014). This research was thus centered on establishing the influence of material flow management on the supply chain performance and subsequently the lead time of road construction projects in Kenya. The study was guided by the following specific objectives: First, to establish the influence of material flow and road construction projects' lead time in Kenya. Secondly, to establish the relationship between material flows, supply chain performance and lead time of road construction projects in Kenya. This study was anchored on Simulation Theory and Goldrat's Theory of Constraints (TOC). Preliminary investigations was carried out by visiting two road construction projects over a period of two weeks to gain an understanding of the ways in which material flow management impacted on supply chain performance & subsequently on lead time of road construction project. This was followed by the main cross sectional survey designed to collect the required data. Stratified purposive sampling was used to select the sample size. The study comprised of a target population of 116 and a sample size of 90 respondents determined by Yaro Yamane Formula (1967). Data was collected using structured questionnaires and interview guides whose reliability and validity were tested at the index of 0.70. The Cronbach's Alpha coefficient was used to measure the reliability on a 5-point Likert Scale for multiple items. Validation of the questionnaire was done by construction and supply chain specialist while content validation was done by pilot survey. Data analysis was done by multiple regression analysis and content analysis. The hypotheses were tested using Pearson chi-square test of independence at a significance level of 0.05. The findings show that supply chain performance had a significant moderating effect on the relationship between material flow management and lead time of road construction projects (R 2 =0.143, F (1, 87) 2.739, p= p= p= p= 0.024, α=0.05). The study concluded that supply chain performance has a moderating effect on the relationship between material flow management and lead time of road construction projects with a predictor model (Pt = 2.488-0.133 X1-0.44Z5-0.382Z6-0.253Z7-0.345Z8). Contractors should acquire an inventory management software to manage material demand and supply. The findings provide a practical and useful tool for construction project managers to audit construction material flow management with an effort to deliver timely projects. KeNHA would also be able to estimate road construction project lead times besides the provision of a material flow-lead time model for scholars.
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