Publication: Canadian Journal of Civil Engineering Show
11 July 2008 The activity-on-arrow (AOA) method can be used in construction projects depending on the project condition, although it is relatively inefficient as compared to the activity-on-node (AON) method. The most critical problem of the AOA method that is yet to be resolved is the application of a logical dummy activity (dummy). This
paper presents a heuristic method that can be used for systematically identifying and applying logical dummies during the creation of an AOA network based on predefined activity dependencies. The heuristic method first identifies logical dummies of one-to-one relationships, and then detects the other multiple relationships in a stepwise manner to remove the redundancies therein. La méthode de l’activité-sur-flèche (ASF) peut être utilisée selon l’état d'un projet, alors qu’elle est relativement inefficace comparée à la méthode de l’activité-sur-noeud (ASN). Le problème le plus critique qui reste à résoudre pour la méthode ASF est l'application d'une activité logique sans fonction (« dummy »). Cet article présente une méthode heuristique qui peut être utilisée pour l’identification systématique et l’application de « dummies »
logiques lors de la création d'un réseau ASF basé sur des dépendances d'activité pré-définies. La méthode heuristique identifie en premier les « dummies » logiques pour les relations de un à un, puis détecte les autres relations multiples par étape afin de supprimer les redondances. Get full access to this articleView all available purchase options and get full access to this article. ReferencesCallahan, M.T., Quackenbush, D.G., and Rowings, J.E. 1992. Construction project scheduling. McGraw-Hill, New York. Clough, R.H., Sears, G.A., and Sears, S.K. 2000. Construction project management. 4th ed. John Wiley & Sons, New York. Harris, R.B. 1978. Precedence and arrow networking techniques for construction. John Wiley & Sons, New York. Hinze, J.W. 2004. Construction planning and scheduling. 2nd ed. Prentice Hall, Upper Saddle River, N.J. Melin, J.W., and Witeaker, B. 1981. Fencing a bar chart. Journal of the Construction Division, ASCE, 107: 497–507. Moder, J.J., Phillips, C.R., and Davis, E.W. 1983. Project management with CPM, RERT, and precedence diagramming. 3rd ed. Van Nostrand Reinhold Company, Inc., New York. O’Brien, J.J., and Plotnick, F.L. 2006. CPM in construction management. 6th ed. McGraw-Hill, New York.
Metrics & CitationsMetricsOther MetricsCitationsCite AsKyunghwanKimK. Kim. Identifying logical dummy activities in an activity-on-arrow network. Canadian Journal of Civil Engineering. 35(7): 739-743. https://doi.org/10.1139/L08-007 Export CitationsIf you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. There are no citations for this item
View OptionsGet AccessView optionsFull TextView Full TextMediaMediaOtherTablesWhich system of network given below completely eliminates the use of dummy activities?
Answer (Detailed Solution Below)Option 2 : A – O – N (Activity – on - Node) Free Quantitative Aptitude Free Mock Test 15 Questions 15 Marks 15 Mins Concepts: Dummy Activity: A dummy is a type of activity which neither requires time nor any resource, but it denotes dependency among the activities. It brings logical correctness in a network diagram and represented by dashed arrow in network diagram. A–O–A (Activity-on-Arrow) Network: In this kind of network system, activities are represented by arrows and events are represented by the nodes connecting the arrows at starting and ending. In A-O-A system to establish interdependency dummy activities are frequently used. A diagram of A-O-A system shown below:  As, CPM and PERT are two different types of A-O-A network system, so in CPM and PERT also there are frequent use of dummy activity. A–O–N (Activity-on-Node) Network: In this kind of network system, activities are represented by nodes and arrows shows the immediate predecessor activity. In A-O-N system there is no need of dummy activity because activities are represented by nodes and their interdependency can be directly denoted by properly connected arrows. A diagram of A-O-N system shown below: Latest HPCL Engineer Updates Last updated on Nov 9, 2022 HPCL Engineer Tentative Answer Key Out on 3rd November 2022! This is in reference to the exam that was conducted on 1st November 2022. The candidates can download the answer key from the official website by using the credentials such as Application Number & Date of Birth. The objections in the answer key can be raised till 6th November 2022. The HPCL Engineer Final Answer Key is expected to be released soon, after which the results will be announced. Why dummy activities are used in activity on arrow diagrams?A dummy is an arrow drawn with dotted lines used to separate tasks that would otherwise start and stop with the same events or to show logical sequence. Two simultaneous tasks start and end at the same events. Solution: Use a dummy and an extra event to separate them.
What is dummy activity in AOA?A dummy activity is an activity added to a project schedule as a placeholder. It has no activity time associated with it.
Why are dummy activities and dummy events used in the network diagram of the projects?Dummy activities often have a zero completion time and are used to represent precedence relationships that cannot be easily (if at all) represented using the actual activities involved in the project. By convention dummies are always shown as dotted arcs in network diagrams.
What is an event activity and dummy activity?When two or more activities are exactly parallel such that they would start at the same node (event) and finish at the same node. A dummy would be inserted between the end of one of the activities and the common finishing node.
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What are dummy activities why are they used in activity on arrow AOA project networks?
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