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Activity-On-Arc(AOA), Activity-On-Node(AON).

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Mustafa Ege
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In network planning techniques, such as PERT,CPM,
There are two possible ways of representing
each project: Activity-On-Arc(AOA), Activity-On-Node(AON).

we know that some project management computer packages use both the network representations.

is there real need for using the AoA representation (Because of minimum dummy arc problem)?

If the AoN representation is only used in project scheduling, what is the nature of the mistake made here?

I couldn’t find any clear-cut and admissible explanation.
Thanks to everybody for their contributions.
Mustafa Ege

Replies

Mike Testro
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Hi Jillian

Welcome to Planning Planet - as you have found this is the forum to learn and share knowledge and experience.

Please remember however that It is not a good idea to liven up a long dead discussion.

BTW whats with the Rabbit Hutch Shop?
 

Best regards

Mike Testro

jillian grey
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Thank you for sharing these helpful information. I learned a lot from it. I really appreciate you guys sharing these information with us.

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John Cornish
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Hi Mal,

Thanks for your supportive comments. And absolutely right to learn for yourself all about forward/backward passes. The S/W just does it faster.

I would be interested to learn what planning tools you’re using in the pharmaceutical industry.

At www.microplanning.co.uk there are two useful .docs to download to help compare/contrast project planning tools. You’re very welcome to make use of them.

Cheers
John
Mal Leadbetter
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In responce the Brads point about Pertmaster, when I started planning we used Hornet. The Arrow on Arrow drawing was based upon A1 sheets, activity numbers taken from a rows and column numbering. So simple! Especially as my senior planner made me draw every thing out be hand first! And then do a forward / backward pass before putting it into the computer. His idea of making me learn some planning principles and not just software. Stood me in good stead since!

Mal
John Cornish
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Hi Brad,

Take a look at Micro Planner X-Pert. This package was designed by Project Managers for Project Managers and yes includes all the goodies like PERT Diagrams with ADM or if you must PDM.

try the free download to compare/contrast with other planning tools.

cheers
John
Brad Lord
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the old days of arrow on node planning, Did any body else use an old MSDOS programme called Pertmaster Advanced which allowed you to do both planning techniques, what a joy it was

regards

Rav B
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AOA - Abort Once Around (such a old topic)

Yes, its true that professionals use both the terminology, Arc as well as arrow.

Depends from which school you have passed from?

Cheers,

Rav
Siva guru
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AOA can represent both Activity on ARROW &Activity on ARC,
as in scheduling we find authors using both the terminologies interchangably.
Dayanidhi Dhandapany
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As Ron rightly mentioned, AOA should stand for Activity on Arrow, from where the term Arc comes to replacing the Arrow?
Bernard Ertl
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IMO, most software supports PDM/AON because the market demand was there. It is easier (more intuitive) for people to work with. Training people to schedule on ADM/AOA systems who don’t know anything about it requires a *lot* of patience.

Bernard Ertl
eTaskMaker Project Planning Software
Raj Maurya
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AON (PDM) is developed to fulfill the shortcomings of AOA method in case of complex project. I guess that’s why most of the softwares support it.
Stephen Devaux
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"But in general activities are not very straight forward with FS relation, I guess that is the reason most of the programme supporting AON(PDM) technique there you can define all other type of dependencies."

Any relationship that can be modelled with complex dependencies and lags can also be modelled using only FS relationships, with greater decomposition and milestones. The FS-only network will have more activities and milestones, but it will be easier to focus on task-completion criteria. And computing critical path DRAG is usually easier in FS-only networks.
PRABHATH PREMASURIYA
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AOA - Activity On Arrow
Finish to Start (FS) relationship only; Dummy activities allowed

AON - Activity On Node
Also called Precedence Diagram Method.
Represent improvement to PERT and CPM by adding lag relationships to activities.
All the four types of relationships allowed.
Start to Start (SS), Start to Finish(SF), Finish to Start (FS) and Finish to Finish (FF).
Arrow indicate dependancy, No dummy activities.
Rashid Iqbal
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Most of the programs inculding Primavera and MS Project use AON. AOA lacks different type of relationships which enable the AON user to model a real life dynamic situation to a ’considerable’ extent.

Though one thing I would like to submit that whenever someone is trying to explain a process, he goes by AOA. AON can’t beat the simplicity of AOA.

Reagrds
Rashid Iqbal
Raj Maurya
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AOA (ADM) is used when the relationship among the activities are clearly defind as FS. But in general activities are not very straight forward with FS relation, I guess that is the reason most of the programme supporting AON(PDM) technique there you can define all other type of dependencies.
Ronald Winter
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I always though that ’AOA’ stood for Activity-on-Arrow, as in arrow diagraming. Did I sleep through another class and miss something?
Bernard Ertl
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IMHO, AON (or PDM) is easier for schedulers to conceptualize in the head from a list of predecessors/successors. Ie. there are less numbers/codes/labels representing the logic network.

AOA (or ADM) is more explicit when the logic network is graphed, but is more difficult to conceptualize from a list of I,J nodes.

Bernard Ertl
eTaskMaker Project Planning Software