Drawing the AOA network Project Management seminar Elements

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Drawing the AOA network Project Management (seminar)

Drawing the AOA network Project Management (seminar)

Elements of an Ao. A diagram • Activity (arrow) – Work element or task

Elements of an Ao. A diagram • Activity (arrow) – Work element or task – Can be real or not real – Name or identificaton of the tasks must be added • Event (node) – The start and/or finish of one or more activities – Tail (preceding) and head (succeeding) nodes

Conventions • Time flows from left to right – Arrows’ direction – Labels’ increase

Conventions • Time flows from left to right – Arrows’ direction – Labels’ increase • Head nodes always have a number higher that of the tail node. This is the same with the arrow labels (letters). • Activity labels are below the arrow (despite the pictures in the textbook) • A network has only one starting and only one ending event.

Graphical representation • • Arrows, nodes, bending Identification of activities Representation of time Representation

Graphical representation • • Arrows, nodes, bending Identification of activities Representation of time Representation of deadlines (external constraints)

Dependency rule b depends on a (b is a successor of a): 1 2

Dependency rule b depends on a (b is a successor of a): 1 2 a 3 b b and c are independent from each other: b 1 a 3 2 c 4

Consequencies of the depencency rule • An event cannot be realised unitl all activities

Consequencies of the depencency rule • An event cannot be realised unitl all activities leading to it are complete. • No activity can start until its tail event is realised.

Merge and burst nodes • Merge nodes: – Events into which a number of

Merge and burst nodes • Merge nodes: – Events into which a number of activities enter and one (or several) leave. • Burst nodes: – Events that have one (or more) entering activities generating a number of emerging activities.

Two errors in logic • Looping: underlying logic must be at fault • Dangling:

Two errors in logic • Looping: underlying logic must be at fault • Dangling: an activity is undertaken with no result

Interfacing • When an event is common to two or more subnetworks it is

Interfacing • When an event is common to two or more subnetworks it is said to be an ‘interface’ event between those subnetworks and is represented by a pair of concentric circles.

Milestones • Events which have been identified as being of particular importance in the

Milestones • Events which have been identified as being of particular importance in the progress of the project. • Identified by an inverted triangle over the event node (occasionally with an imposed time for the event)

Multiple starts and finishes • Only used in computer programs • All starting activities

Multiple starts and finishes • Only used in computer programs • All starting activities can occur at the start and all finish activities will occur at the end of the project.

Hammock activities • Artificial activities created for the representation of the overhead cost with

Hammock activities • Artificial activities created for the representation of the overhead cost with the aim of cost control. • Embrace activities belong to the same cost centre • Zero duration time (not taking part in the time analysis) • Overhead cost rate is assumed to be constant over the life of the hammock.

Dummy activities • Activities that do not require resources but may in some cases

Dummy activities • Activities that do not require resources but may in some cases take time. • They are drawn as broken arrows. • They are always subject to the basic dependency rule. • Thre occassions to use dummies: – Identity dummies – Logic dummies – Transit time dummies

Identity dummies • When two or more parallel activities have the same tail and

Identity dummies • When two or more parallel activities have the same tail and head nodes.

Logic dummies • When two chains of activities have a common node yet they

Logic dummies • When two chains of activities have a common node yet they are at least partly independent of each other. Hint: examine ANY crossroads. • Example: – Activitiy c depends on activity a – Activity d depends on activities a and b • Solution: – separate c from b with a dummy activity

Transit time dummies • If a delay must occur after the completition of an

Transit time dummies • If a delay must occur after the completition of an activity before the successor activity can start.

Overlapping activities • If the activities are not fully discrete • The second activity

Overlapping activities • If the activities are not fully discrete • The second activity can start before the first is completed but not before it is at least partly completed. 1 1 10 a a 1 5 20 b 10 a 2 b 1 11 b 2 20

Readings • Lockyer – Gordon (2005) Chapter 11

Readings • Lockyer – Gordon (2005) Chapter 11

Thanks for the attention!

Thanks for the attention!