Transcript Chapter 3 – PROJECT NETWORK DIAGRAM
PROJECT NETWORK DIAGRAM
PREPARED BY : NOR AZAH BINTI AZIZ KOLEJ MATRIKULASI TEKNIKAL KEDAH 1
OBJECTIVES
• • • • • • Define Network Diagram Purpose of Network Diagram Method : Activity On the Node (AON) Identify ES, EF, LS, LF using Forward Pass Calculation and Backward Pass calculation Identify Critical Path Identify Slack Time 2
INTRODUCTION
• • •
A PND is a pictorial representation of the sequence in which the project work can be done.
The activities and its duration are the basic building blocks needed to construct a graphic picture of the project Its provide - the earliest time at which work can be begin on every activity that makes up the project - the earliest expected completion date of the project
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IMPORTANCE OF ND
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ND can be used for ; i) Planning : gives a clear graphical picture of the relationship between project activities ii) Implementation : when updating the project file with activity status and estimate to completion data, the ND is then automatically updated and can be printed or viewed iii) control : while updated ND will retain the status of all activities, the best graphical report and controlling project work will be Gantt Chart
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METHODS
I) THE ACTIVITY ON THE NODE ( AON)
• • • •
Basic unit of analysis in ND is the activity Each activity is represented by a rectangle ( activity node) Arrows represent the predecessor/successor relationship between activities Every activity in the project will have its own activity node ( each rectangle)
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METHODS
I) THE ACTIVITY ON THE NODE ( AON)
B D A F C E PDM format of a project network diagram 6
METHODS
I) THE ACTIVITY ON THE NODE ( AON) Dependencies A dependency is simply a relationship that exists between pairs of activities 4 types of activity dependencies
A B FS : A finishes, B start 7
METHODS
I) THE ACTIVITY ON THE NODE ( AON) Dependencies
A B FF : A finishes, B finish A A SS : A start, B start 8
METHODS
I) THE ACTIVITY ON THE NODE ( AON) Dependencies
A B SF : A starts, B finish 9
I) THE ACTIVITY ON THE NODE ( AON)
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I) THE ACTIVITY ON THE NODE ( AON)
Creating an initial project network schedule B 3 D 5 Start A 1 C 2 E 2
Forward Pass calculations
F 3 End 11
EST, LST, EFT, LFT
• CPM uses the following times for an activity
EST LST EFT LFT
- Early Start time is the earliest time the activity can begin - Late Start Time is the latest time the activity can begin - still allow the project to be completed on time - Early Finish Time is the latest time the activity can end - Late Finish Time is the latest time the activity can end - still allow the project to be completed on time 12
Forward Pass calculations
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Backward Pass calculations
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CRITICAL PATH METHOD (CPM)
• • • • • • An effective way to analyze complex projects Represent the critical set of activities to complete a project Help to focus on essential activities which are critical to run the project Allows the project manager to concentrate on important activities CP is the longest path on ND and the most important part Any delays on the CP will lead to delay of the project 15
CRITICAL PATH METHOD (CPM)
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FLOAT
• • • • Also known as slack, total float and path float Is computed for each task by subtracting EFT from the LFT ( @ the early start from the late start) Is the amount of time the task can slip without delaying the project finish date.
Free float is the amount of time a task can slip without delaying the early start of any task that immediately follows it.
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Slack Time calculations
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EXAMPLE
1. TABLE 1 shows the activities and the durations required to complete a construction project, including the precursor activity.
Refering to the TABLE 1: i) draw the project network diagram.
ii) state the activities on the critical path.
iii) calculate the minimum duration of the project.
Activity Precursor Duration (week)
A 7 B C D E F A A A,B B,C D,E 6 5 4 3 2 19
0 0
START
0 0 0
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7 A 0
0
7 ES
D
EF activity LS F LF 7
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13 B 7 0 13 7
5
12 C 9 2 14 13
4
D 17 13 0 17 14
3
E 16 14 1 17 17
2
19 F 17 0 19 19 19
END
19 19 project network diagram 20