The Critical Path Method
Presented by Antonio Prensa,
MBA, PMP, CCP, CSTE for Project
Management Institute Puerto Rico
Chapter
June 20, 2002
San Juan, Puerto Rico
"I believe that this nation should
commit itself to achieving a goal, before
this decade is out, of landing a man on
the moon..." - John F. Kennedy,
May 27,1961
On July 20, 1969, just eight years after Kennedy's
speech, Apollo 11 landed two men on the moon.
This achievement was possible only with careful
production planning that included the critical path
method.
NASA used the critical path method to help
determine an efficient schedule for the tasks that
led to the moon landing.
Discussion Topics
Background
Some questions about the project
What is the Critical Path Method
(CPM)?
Why the CPM?
How to use the CPM ?
Questions and Answers
Background
The critical path method (CPM) was
invented by project managers in the
early 1950's.
The US Navy adapted and improved it
to manage the Polaris missile project in
the late 1950's
Some questions about the
project
How long will the entire project take to
complete?
Which activities determine total project
time?
Which activity times should be
shortened, if possible, or in other
words, how many resources should be
allocated to each activity?
What is the CPM?
CPM
Critical Path Method (CPM), is a procedure for
using network analysis to identify those tasks which
are on the critical path: ie where any delay in the
completion of these tasks will lengthen the project
timescale, unless action is taken.
For all tasks off the critical path, a degree of
tolerance is possible (eg. late start, late completion,
early start, etc.).
Network charts and CPM analysis used to be carried
out by hand.
Software is now available which requires the user
only to enter the tasks, duration of each task and
dependencies upon other tasks; a network chart and
CPM is then automatically created.
Why the CPM?
The CPM formally identifies tasks which
must be completed on time for the whole
project to be completed on time
Identifies which tasks can be delayed for a
while if resource needs to be reallocated to
catch up on missed tasks
It helps you to identify the minimum length of
time needed to complete a project
The CPM determines both the early start and
the late start date for each activity in the
schedule.
How to use the CPM?
Project Network Diagram
• Any schematic display of the logical relationships
of project activities.
2
4
6
1
8
3
5
7
How to use the CPM?
List
Listthe
theactivities
activities
And
Andrelationships
relationships
Sequentially
Sequentially
Arrange
Arrangeall
all
Activities
Activitiesfrom
from
“Start”
“Start”
Create
Createaastart
start
node
node
Repeat
Repeatprocess
process
from
fromsuccessors
successors
for
forall
allactivities
activities
Draw
Drawarrows
arrowsfrom
from
Start
Startnode
nodeto
tothe
the
First
Firstactivity’s
activity’snode
node
Double
Doublecheck
checkfor
for
missed
missed
relationships
relationships
How to use the CPM?
Early
Start (ES)
Early Finish
(EF)
Task duration
Late
Start (LS)
Late
Finish (LF)
How to use the CPM?
Task ID
Duration
A
B
C
D
E
F
G
H
7
3
6
3
3
2
3
2
Dependency
A
B
D,F
B
C
E,G
How to use the CPM?
0
A
7
7
(7)
C
13
13
(6)
G
16
(3)
16
S
H
(2)
0
B
3
3
(3)
D
6
F
5
(3)
3
(2)
6
E
(3)
9
18
F
How to use the CPM?
0
0
A
(7)
7
7
7
7
13
13
G
(6) 13
13
(3) 16
C
16
16
S
H
16 (2)
0
7
B
3
(3) 10
3
10
3
11
D
6
F
5
(3) 13
(2) 13
6
13
E
9
(3) 16
18
18
F
How to use the CPM?
0
0
A
(7)
7
7
7
7
0
S
0
7
B
13
G
(6) 13
13
(3) 16
C
0
3
(3) 10
7
13
3
10
D
6
(3) 13
11
F
5
(2) 13
8
16
0
7
3
16
6
13
H
16 (2)
E
9
(3) 16
7
0
18
18
F
Summary
Critical Path Analysis is an effective and
powerful method of assessing:
Tasks which must be carried out
Where parallel activity can be carried out
The shortest time in which a project can be
completed
Resources needed to achieve a project
The sequence of activities, scheduling, and
timings involved
Task priorities
Do you need more
information?
Project Management:A systems approach to
Planning, Scheduling, and Controlling –
Harold Kerzner, Six edition.
Project Management: A Managerial Approach
– Jack R. Meredith, Samuel J. Mantel, Fourth
Edition.
Web Search Engine – key word: The Critical
Path Method or The CPM.
Contact me at:
Antonio Prensa
Email: [email protected] /
[email protected]
Phone: (787) 751-9800 ext. 3725
The Critical Path Method
Presented by Antonio Prensa,
MBA, PMP, CCP, CSTE for
Project Management Institute
Puerto Rico Chapter
June 20, 2002
San Juan, Puerto Rico