Chapter 7 Flashcards
Network diagrams
shows project activities or tasks and their logical relationships
also shows events (instants in time; start of an activity)
2 construction methods of network diagrams
- AON mode (activity on mode)
2. AOA mode (activity on arrow)
AON mode
- each activity (work package or task) in project is represented by a node
- project represented as arrows and nodes (arranged in sequence as specified by immediate predecessors)
2 types of dependency relationships
- mandatory
- sequence of 2 actions can’t be reversed
- dependency can’t be eliminated - discretionary
- sequence is a matter of choice
- dependency can be eliminated (and activities overlapped to speed up process = fast tracking)
creating a project network
created using list of activities from Work Breakdown Structure and their predecessors
What happens when a delay occurs in one of the activities on the critical path?
the whole project is delayed
Early times: early start and early finish
earliest that activities can be started (ES) and finished (EF)
- ES depends on the EF of its predecessor
- do not consider potential constraints
Late times: late start and late finish
latest allowable times an activity can start (LS) and finish (LF) without delaying project completion
- LF depends on the LS for its successor
Total slack
amount of allowable deviation between the latest an activity must take place and the earliest it can take place
–> how much an activity can be delayed without delaying the whole project
Critical path
- has no or the least slack
- the time a project takes is dependent of the critical path
- it is the longest path
activities on the critical path
critical activities
free slack
the time an activity can be delayed without delaying the start of any successor activity
Alternative precedence relationships: Start-to-start (SS)
Start second task ___ days after first task starts
Alternative precedence relationships: Start-to-finish (SF)
Finish second task ___ days after first task starts
PDM (Precedence Diagramming Method)
shows the kinds of relationships in a project
- Start activity when predecessors are only partially completed
- Start activity n days after start of predecessor
- Start activity n days after predecessors are completed
- Finish activity n days after finished predecessor
Alternative precedence relationships: Finish-to-start (FS)
_______ day lag between predecessor and successor
Start second task ___ days after first task finishes
Alternative precedence relationships: Finish-to-finish (FF)
finish second task ___ days after first task finishes
–> mostly used with zero lag where activities must end on the same day
Time Constrained Project
- A project that must be completed by an
imposed date - Time is fixed, resources are flexible
–> sometimes resources are required to ensure project meets schedule
Resource Constrained Project
- A project in which the level of resources available cannot be exceeded
- Resources are fixed, time is flexible
- -> inadequate resources will delay the project
- Resource levelling (or smoothing) involves attempting to even out demands on resources by using slack (delaying non critical activities) to manage resource utilisation.
Resource allocation
assigning resources to activity
Workload (and formula)
amount of work imposed on resource
working days/year) x (productive working hours/day
Resource Loading
amount of particular resource needed to conduct all allocated activities
Loading for particular resources depends of
- amount of resource needed by project activities
2. start and finish dates of those activities
Resource levelling
alter schedules of project activities such that the resultant workload for a required resource is somewhat uniform throughout the project
–> do this by adding slack