Precedence Diagramming Method Research Articles

Use of PERT (program evaluation and review technique) and PDM (precedence diagramming method) in organizing modern vegetable seedling production

Propagation of quality vegetable seedlings is a key of successful vegetable production in an open field and in protected areas. The research is aimed at the production process itself, analyzing it from technological and organizational aspects. Based on a detail calculation of time, means and costs, the researchers obtained the duration of production in days, regarding the propagation of pepper, tomato, cabbage and lettuce seedlings, taking into consideration different technological requirements of crops, ripening time, delivery time and an optimal use of the propagation area. The use of the Program Evaluation and Review Technique required more attention when making a production plan, resulting in the introduction of activities, the realization of which required only the flow of time to harmonize the monitoring of real activities. By using the Precedence Diagramming Method this problem was overcome with predefining the type of relationship between the interdependent activities (Finish-to-Start, Finish-to-Finish, Start-to-Start, and Start-to-Finish).

Comparison of different algorithms for time analysis for CPM schedule networks

Traditional Critical Path Method (CPM) and its different generalizations have become the prevailing technique in managing complex projects over recent decades. Among them, Precedence Diagramming Method (PDM), with its four precedence relationships, has become the most popular due to its increased flexibility in modeling complex project logic. Despite the four well-known precedence relationships, CPM/PDM still suffers from modeling shortcomings.Developments such as conditional logic, maximal relationships, point-to-point relationships, continuous relationships, and non-linear activities attempt to remedy these problems. However, these improvements require more complex and sometimes iterative time analysis.Monte Carlo (MC) simulation, which calculates the effects of risks on the project duration, also requires numerous repetitions of the deterministic time analysis. It is especially true if the network contains the developments mentioned above. In these cases, the time analysis speed is of great importance.The goal of this study is a) to implement different algorithms for time analysis that perform better than the traditional time analysis, b) to compare their speed on large-scale artificially created projects, c) to make suggestions regarding which algorithms are suitable in different cases d) to develop a database containing artificially created networks to serve as a basis for benchmarking for researchers and developers working in the field of project planning.Comparisons were based on networks with at least 1000 activities. Results show that, depending on the sample network's structure, different algorithms perform well. Therefore, different time analysis algorithms are necessary to implement into the scheduling tools, and they can decide which algorithms perform better.

MULTI-OBJECTIVE SYMBIOTIC ORGANISMS OPTIMIZATION FOR MAKING TIME-COST TRADEOFFS IN REPETITIVE PROJECT SCHEDULING PROBLEM

Time-cost problems that arise in repetitive construction projects are commonly encountered in project scheduling. Numerous time-cost trade-off approaches, such as mathematical, metaheuristic, and evolutionary methods, have been extensively studied in the construction community. Currently, the scheduling of a repetitive project is conducted using the traditional precedence diagramming method (PDM), which has two fundamental limitations: (1) progress is assumed to be linear from start to finish; and (2) activities in the schedule are connected each other only at the end points. This paper proposes a scheduling method that allows the use of continuous precedence relationships and piece-wise linear and nonlinear activity-time-production functions that are described by the use of singularity functions. This work further develops an adaptive multiple objective symbiotic organisms search (AMOSOS) algorithm that modifies benefit factors in the basic SOS to balance exploration and exploitation processes. Two case studies of its application are analyzed to validate the scheduling method, as well as to demonstrate the capabilities of AMOSOS in generating solutions that optimally trade-off minimizing project time with minimizing the cost of non-unit repetitive projects. The results thus obtained indicate that the proposed model is feasible and effective relative to the basic SOS algorithm and other state-of-the-art algorithms.

Survey of precedence relationships: Classification and algorithms

Abstract Precedence relationships used in project planning mean for most professionals the traditional Start-to-Start-z (SSz), Finish-to-Start-z (FSz), Finish-to-Finish-z (FFz) and Start-to-Finish-z (SFz) relationships where z stands for the minimal necessary duration between the defined endpoints (Start or Finish) of the activities. These relationships have been serving professionals for more than 50 years, and there is not much visible effort for further developing them, despite some well-established critiques on the modeling capability of the Precedence Diagramming Method (PDM). The purpose of this research is: a) gathering those well-known and lesser-known developments of logical relationships that can be used for modeling some, so far, un-modelable problems b) classifying them by using a classification scheme that has been developed for this purpose and c) developing algorithms for time analysis when missing. The following earlier developments are discussed: maximal precedence relationships, point-to-point precedence relationships, continuous precedence relationships, relationships with AND/OR logical switches and bidirectional precedence relations. The classification shows that 24 types of logical relationships exist, but that algorithms exist only in four types, and are missing in twenty cases. The missing algorithms are provided here. The main contributions to the Body of Knowledge are: a) providing a classification scheme for precedence relationships b) definition of 24 precedence relationships based on the classification categories c) developing the missing time analysis algorithms for twenty cases d) presenting a single unified algorithm that handles all the 24 types of precedence relationships.

Alternate beeline diagramming method network analysis for interdependent design entities

PurposeThe design phase is generally characterized with two-way multiple information exchanges/overlaps between the interdependent entities. In this paper, entity is a generic term to represent teams, components, activities or parameters. Existing approaches can either capture a single overlap or lack practical application in representing multiple overlaps. The beeline diagraming method (BDM) network is efficient in representing multiple overlaps for construction projects. However, it considers any entity as indivisible and cannot distinguish partial criticality of entities. In reality, the design phase in any construction project is driven by need basis and often has numerous interruptions. Hence, there is a need to develop an alternate network analysis for BDM for interruptible execution. The paper aims to discuss these issues.Design/methodology/approachA pilot study is conducted to formulate the hypothetical examples. Subsequently, these hypothetical BDM examples are analyzed to trace a pattern for criticality. This pattern study along with the existing precedence diagramming method network analysis enabled to derive new equations for forward pass, backward pass and float. Finally, the proposed concepts are applied to two design cases and reviewed with the design experts.FindingsThe proposed network analysis for BDM is efficient for interruptible entity execution.Practical implicationsThe proposed BDM network is an information-intensive network that enables the design participants to view the project holistically. Application to two distinct cases emphasizes that the concept is generic and can be applied to any project that is characterized with beelines.Originality/valueAn alternate network analysis for BDM is investigated for interruptible entity execution. This study also clarifies the related concepts – interdependency, iteration, overlaps and multiple information exchanges/linkages.

Construction industry project planning information system

The planning processes in construction industry nowadays develop the project management plan and the projects documents to carry out the project. The system being built is purposed to help project manager do project planning such as analyse risks probability and risks impact on projects using Probability Impact Matrix (PIM), and for project scheduling by showing the relationship between activities using Precedence Diagramming (PDM) method in order to project manager know the optimal project timing estimation. Based on the analysis and the results of system testing already done, it can be concluded that the system could help the project manager in identifying the risks that are likely to negatively affect project implementation and help project manager in scheduling project. The cause of delay in project are there are no risk recorded, ignoring the risks that could have negative impact on the implementation of project, and there is no risk handling, and then the scheduling done by the project manager did not show the specific relationship between the project activity. Then system is expected could help project managers to implement monitoring and controls in project execution.

A New Networking Technique—The Beeline Diagramming Method

The Critical Path Method (CPM) has gradually increased in importance in the construction industry since the Arrow Diagramming Method (ADM) and the Precedence Diagramming Method (PDM) were introduced in 1956 and 1961, respectively. In an improvement over the ADM, the PDM is able to represent overlapping relationships between consecutive activities. It is limited to representing overlapping relationships only as four combinations that connect the starting and finishing points of two consecutive activities, however; it cannot express the relationships at the exact point of interrelation if that point is in the middle of the activity’s duration. Further, when two consecutive activities have respective multiple milestones that should be connected independently, the PDM cannot represent the multiple overlapping relationships precisely. This research proposes the Beeline Diagramming Method (BDM) as a new networking technique that can represent all kinds of overlapping relationships between activities. The basic concept, principle, interpretation methods, and schedule computation methods of the BDM are defined in this paper.

Singularity functions for continuous precedence relations and nonlinear activity-time-production functions

Abstract Two fundamental limitations of the Precedence Diagramming Method (PDM), which currently hinder the proper modeling of construction projects are discussed and overcome. Activities in the original model are (1) assumed to progress linearly from their start to their finish, which is rarely true in construction projects, and (2) connected only via their end points. The extension that is presented here therefore enables a general description of activity-time-production functions: A new type of precedence relation is defined and this new model can handle nonlinear activities. Theoretically, proper modeling of overlapping activities has been impossible with traditional precedence relationships. This is due to the fact that traditional precedence relations create logic links only between endpoints of activities. Yet overlapping should be defined as a ‘continuous’ relation that uses time or work (e.g. location) units between all points of a predecessor activity and all points of its successor. Continuous precedence relations for scheduling techniques have been envisioned earlier, but the model presented there was able to function properly only if the successor was linear. The contribution of this paper is to derive an algorithm for activity pairs that are connected by a continuous relation and can be nonlinear. Comparing calculations based on traditional calculus and singularity functions validates the new approach.

An Estimation of the Learning Curve Effect on Project Scheduling with Working Days Calculation

In this paper, a learning curve effect on project duration is shown – calculating with working days only - and estimated with the help of simulated examples. Although learning is an essential part of our life, traditional scheduling techniques cannot efficiently handle the learning curve effect. It is assumed that the duration of impending repetitive activities are shorter due to the learning curve effect if the gap between consecutive activities is small enough. Taking into account the effects of the learning curve (or experience curve), it is possible to better predict project duration thus saving time and money. This effect normally results in shorter project duration. Although the effect is a “simple” calculation, it leads to an exponential time algorithm if the learning effect is applied to traditional project scheduling techniques like CPM, or Precedence Diagramming Method. In this paper, an integer programming model is developed, and an efficient algorithm is used to establish project duration. (This paper is an extended version of Levente Malyusz: Learning curve effect on Project Scheduling, Procedia 2016.)

An Estimation of the Learning Effect on Project Cost Scheduling

The effect of the learning phenomenon (learning curve) on project cost and scheduling is discussed in this paper. Although learning is an essential part of life, traditional scheduling techniques cannot efficiently handle the learning curve effect. It is assumed that the durations of impending repetitive activities, performed by the same workers, are shorter due to the learning curve effect, therefore no additional acceleration cost is necessary and the deployment cost before the second activity can also be neglected if the gap between consecutive activities is small enough. Taking into consideration the effects of the learning curve (or experience curve), it is possible to reduce project duration and cost. According to this study 0.4%-1% reduction in project cost and a 9-40% reduction in acceleration cost on a given project duration is available. Although the effect is a “simple” calculation, it leads to an exponential time algorithm if the learning effect is applied to traditional project scheduling techniques like Critical Path Method (CPM), or Precedence Diagramming Method (PDM). In this paper, an integer programming model is developed, and an efficient algorithm is used to estimate the project cost curve. The results are validated through an artificial example project.

PDM Time Analysis with Continuous and Point-to-Point Relations: Calculations Using an Artificial Example

Two major generalizations of the Precedence Diagramming Method (PDM) and an algorithm solving the generalized network are discussed in this paper: a) Two new types of precedence relations are introduced: minimal point-to-point and minimal continuous relations; b) Non-linear production-time functions can be defined in order to better adapting the model for real life situations. The activity progress-in-time function can be any strictly increasing continuously derivable function. The mathematical model, and the algorithm is shortly described, then the calculations are shown in details through an artificial example project. The emphasis is on the calculations, as this example project will be used in other papers on generalized PDM models.

How Many Types of Critical Activities Exist? A Conjecture in Need of Proof

The Precedence Diagramming Method (PDM) is the prevalent scheduling technique used for temporal planning of projects. Critical paths require special attention during the course of planning as their lengths define the project duration. However, increasing/decreasing the duration of an activity on the critical path does not necessarily results in a longer/shorter project duration. Responses of the critical path in a PDM network for small changes of the duration of a critical activity can be classified into six categories, while nine different possible categories exist in theory. The modeling capabilities of PDM recently have been extended by the introduction of a) point-to-point relations, b) continuous relations, and c) non-linear activity (production-time) functions. The paper presents the following conjecture that needs a proof: The number of existing types of critical activities remains six when using the recently developed precedence relations and non-linear production-time functions for activities. The theory of the different types of critical activities is briefly discussed and the mathematical model of the generalized PDM technique is presented.An additional feature presented in the paper beyond defining the conjecture is the introduction of influence lines for project duration that have never been used in project management before. Influence lines can be of great help in understanding the nature of critical activities. Papers providing solutions or confuting this conjecture will be honored with the CCC 2017 award.

Learning Curve Effect on Project Scheduling

In this paper a simple learning curve effect on project scheduling is shown with a help of an artificial example. Although learning is an essential part of our life, traditional scheduling technique can not handle efficiently the learning curve effect. It is assumed that the duration of upcoming repetitive activities are shorter due to the learning curve effect if the gap between consecutive activities is small enough. Learning curve theory can be applied to predicting cost and time to complete repetitive activities. Taking into accounts the effects of learning curve (or experience curve) one can get better future prediction on project duration and can save money and time. This effect normally result in shorter project duration. Although the effect is “simple” calculations are cumbersome if the learning effect is applied on traditional project scheduling techniques like Critical Path Method, or Precedence Diagramming Method as calculation lead to an exponential time algorithm.

The Possibilities for Better Project Tracking based on the New Developments of the Precedence Diagramming Method

Tracking a schedule is one of the most challenging tasks for the project control personnel. The problems they face arise as a consequence of the limitations of the existing Precedence Diagramming Method, namely that activities are assumed to be linear and that precedence relations control only the end-points of the activities. Recent developments of the Precedence Diagramming Method such as continuous and point-to-point relations give the opportunity to control as many points as necessary during the tracking process. However, a method that helps to create as-built production-time activity functions is still missing. The result of this paper is the development of new types of constraints that can be used to monitor the activities in progress, and that allow one to re-calculate the plan based on as-built data.

History and Some Latest Developments of Precedence Diagramming Method

History and Some Latest Developments of Precedence Diagramming Method

Application of Relationship Diagramming Method (RDM) for Resource-constrained Scheduling of Linear Construction Projects

The traditional techniques for project scheduling such as Arrow Diagramming Method (ADM) and Precedence Diagramming Method (PDM) are continuously undergoing improvisation in order to replicate real-time construction scenario. Quite often, these methods are criticized for their limited information capturing ability. Relationship Diagramming Method (RDM) proposed by Plotnick in the recent past, is an improved variant of PDM, which can store additional information on relationships that would improve the scheduling process. In addition to basic data on the activities, additional information can be represented through five codes in RDM. Sequencing of activities in a construction project is primarily driven by the construction logic and/or the availability of resources. There is scope for arriving at alternate sequences with varying availability of resources to achieve the objectives of project scheduling as long as the construction logic is preserved. In order to achieve such a resource-constrained project scheduling, additional information on the restraints of the activities are necessary, which can be modelled using RDM through one of the five codes of RDM. The objective of this paper is to explore and exploit the Reason/Why code of RDM. The Reason and Why codes are associated with a restraint and for recording the description respectively. An activity's dependence on a resource has been captured using Reason/Why code in this study. It has been attempted to understand the impact of varying resource availability using an empirical equation on sequencing such resource dependent activities and its effect on critical path. The proposed concept is tested with data from a repetitive high rise construction project. The preliminary results have been well received.

지열발전 시추프로젝트의 4D 정보화기반 통합관리 시스템 개발

Deep drilling project should be managed systematically and efficiently because it is significantly influenced by various related factors having uncertainty and high risk in terms of economy and effective management. In particular, drilling project involves participants from various sectors including necessary service company and it also needs their collaboration by sharing related information occurring at drilling process in order to secure efficient performance management. We developed 4D (3D + time) information based visualization system for progress management by combining 3D design model and predicted optimized control parameters for each section in geothermal well design. We also applied PDM (precedence diagramming method) to the system in order to setup the effective process model and hooked it up to 3D information based on precedence relation and required time for informatized process network.

Merging PDM, RSM and LSM - Scheduling Approaches into a Single Construction Project Scheduling System

There are projects for which the classical Critical Path method (CPM) or Precedence Diagramming Method (PDM) scheduling techniques are not the most suitable. Several alternative approaches have been developed over the last two decades to cope with the scheduling requirements of construction projects that are made of either repetitive activities or activities that have a linear development. Construction projects, and more specifically large-scale construction endeavors, are often composed of a mixture of repetitive activities, linear activities and more conventional project activities. The approach that is proposed in the present article enables construction practitioners to consider these three types of activities in a unique scheduling model — called Unified Project Scheduling System (UPSS) — that has a level of complexity similar to the one of CPM or PDM. UPSS has been designed so that most of the resource-constrained project scheduling algorithms can be used.

CPM Schedule Summarizing Function of the Beeline Diagramming Method

The schedule hierarchy in a construction project generally has multiple levels. The highest level is a milestone schedule, and is represented in bar chart format. The middle level is an integrated project schedule, and is represented in the Critical Path Method (CPM) format. The lowest level is a detailed working schedule, and is usually represented by a bar chart. Traditional scheduling techniques, such as the Arrow Diagramming Method, or the Precedence Diagramming Method, cannot represent all the schedules within a schedule hierarchy in identical formats. However, the Beeline Diagramming Method (BDM) technique can represent all kinds of schedule, within a schedule hierarchy, in CPM format. I describe the basic concepts, principles, interpretation methods, and schedule computation methods of the BDM as a new networking technique that can represent all kinds of overlapping relationships between activities. I then present an example of representing all levels of schedules within a schedule hierarchy, using the BDM technique, as well as BDM networks of levels 2, 3, and 4, in a real construction project.

CPM 공정계획의 PDM 중복관계를 BDM 중복관계로 전환시키는 방법

The reason why most scheduling softwares currently using at construction projects adopt PDM (Precedence Diagramming Method) is that it can express an overlapping relationship between activities. However, the overlapping relationships in PDM are represented only by combinations of four overlapping types that connect the start and finish points of two activities, therefore, PDM cannot express efficiently the relationships between any middle points of two activities if they should be represented. This research proposes the method of transforming the four overlapping types of PDM to the overlapping relationships of BDM(Beeline Diagramming Method), new networking technique, that can connect the inter-relationships at any middle points of two activities as well as express multiple overlapping relationships. The proposed method will help not only to improve an efficiency of scheduling but also to upgrade the scheduling technique because BDM technique has a lot of unique advantages in scheduling.