Project network scheduling and S-curve

VARIOUS STAGES
OF
PROJECT

PAVE A PATH
FOR
SUCCESSFUL COMPLETION

STATUS UPDATING THROUGH
NETWORK AND
GIVING EARLY WARNINGS

DATA COLLECTION

PLANNING & SCHEDULING

THINKING

Project :
A project is the means of converting a vision, a dream or a
need to reality.
A Project is a set of activities which are networked in an
order and aimed at achieving the defined goals for which
the project is undertaken. Upon completion of all the
activities, the goals of the project will be achieved.
Management : Management is the technique of
understanding the problems, needs and controlling the use
of Resources, Cost, Time, Scope and Quality.

Project Management : It is an art of controlling the cost,
time, manpower and hardware & software resources
involved in the project.
“Completion of Project on time within Budget without
comprising Quality”

Project Management Plan
All the detailed planning work done for different
aspects of the project is integrated into one single plan
known as the Project Management Plan.

This plan is used to control the project and acts as the
baseline plan for the project. Once the plan is finalised
by the project manager and his team it should be
approved by the project's sponsor.

The Project Management Plan establishes the project's:

Why; What; Who; When; How and How much

The „Why‟ is from the business case.

„Why‟ and „What‟ are management statement of the success
criteria and should be agreed with the project sponsor.

The 'Who' shows – who will do the work and stakeholder
awareness of project.

The „When‟ deals with the schedules and phasing for the
project.

The „How‟ which is the project manager vision to implement
project from beginning to end – IT requirements, the tools and
techniques to be used, validation of the project deliverables,
technical issues, risk management, resources, procurement,
quality needs etc.

The „How Much‟ covers the costs and budgets of the
project.

STAGES

PLANNING Most important phase of the project
management.
SCHEDULING
Planning is an art and science of
converting a set of objectives to
CONTROLLING realization through a series of steps
executed in an organized and
CLOSING
predicted way so that there will be
less requirement of changes in the
plan later on.
The old saying “Plan the work, Work
the plan”

STAGES

PLANNING
Scheduling Phase is the process
of formalizing the planned activities,
SCHEDULING assigning the durations, resources
and sequence of occurrence in
consultation with the team
CONTROLLING
members.

CLOSING Planning and Scheduling phases are
under taken before the actual
project starts.

STAGES

PLANNING Controlling phase is undertaken during the
actual project implementation.
SCHEDULING Project controlling is a mechanism established
to determine deviations from the project
base schedule, to re-plan & reschedule
CONTROLLING during implementation to compensate the
deviations on the basis of commissioning
minima, flow of resources like
CLOSING
finance, manpower, equipment &
application techniques.

STAGES

PLANNING Closing phase is the last phase of the
project which brings close out of the
complete project. Whatever the project
SCHEDULING requirements are pre-defined, during this
phase the total delivery is made and it is
accepted by the customer.
CONTROLLING
Maximum conflicts can arise in the project
during this phase between those who have
CLOSING worked to deliver the outcome (contractor)
and those who are accepting the results of
the work (customer).

WBS
• For effectively plan and manage the work, the entire
scope of the total project is reviewed and decomposed
or broken down into discrete tasks giving rise to what is
known as the Work Breakdown Structure (WBS).
• WBS is a task oriented family tree, which forms the
foundation tool or backbone for planning and controlling
the entire project. The WBS provides a graphical
representation of all the project activities.
• The lowest level of the WBS is the work package which is a
group of activities. At the work package level, it should be
possible to assign the work, estimate its duration and cost
and also keep a track of the project's progress.

WBS
WBS Levels:
Level 1 (L1) - The highest or the top-most level of the WBS is
generally referred to as Level 1 of the WBS. This will be a single task
which is the Project or Project Name.

Level 2 (L2)- This can be based on the project phase, the product
of the project or the organizational departments.
If level 2 is based on Project, Tasks are Engineering, Manufacturing,
Construction and Testing & Commissioning.

Parent-child relationship
Each level of the WBS has a parent-child relationship. The parent
task in the WBS will finish only after all its children tasks are
complete.

WBS
TYPICAL WBS OF A PROJECT
OVERALL PROJECT

ENGINEERING PROCUREMENT CONSTRUCTION

SITE MOBILISATION
PLACEMENT OF
BASIC ENGINEERING
ORDER ON VENDORS
CIVIL WORK

DETAILED
ENGINEERING MANUFACTURING &
Civil work for Civil work for
DELIVERY Piling work
Main equipment Aux. Facilities
PROJECT
ENGINERING STRUCTURAL STEEL WORK

EQUIPMENT INSTALLATION

PIPING INSTALLATION

ELEC. INSTALLATION
EQUIPMENT
RECEIVED AT SITE INSTRUMEN. INSTALLATION
( …%)
INSULATION & PAINTING

COLD COMMISSIONING

HOT COMMISSIONING

Bar Chart
Bar Chart

•
Representation
It is the graphical representation of the various
activities with respect to its time-bound for
completion for any project.

• It consists of two (2) coordinates.
 Ordinate(X-axis) represents the duration of time
required for completion of activities.
 Abscissa(Y-axis) represents the jobs to be
performed.
 The length of the bar shows the time required by
the activity for its completion.

Typical Bar Bar Chart

Sl.
Chart Duration in Months
Activities
No. 1 2 3 4 5 6 7 8 9 10 11 12
1. AWARD OF CONTRACT

2. SURVEY WORK

3. EXCAVATION

4. FOUNDATION & WALLS

5. SLAB CASTING

6. BRICK WORK

7. PLUMBING & ELECTRICAL WORK

8. FINISHING WORK

1 2 3 4 5 6 7 8 9 10 11 12
Duration in Months

Y
X

Network

In today’s globalized market place, to stay ahead of all means
facing tremendous pressure.“Time is crucial, Time is money”.
An excellent but delayed project means cost overruns.
In this scenario proper scheduling of the project is even more
of a concern than ever before in managing the project.
Many of us have heard of the term networks in relation
to projects.
What is the project network? What role does it play in
managing the project?
A project network can be described as:
A set of activities or the schedule of all the activities required to
complete the aims and goals of the project in stipulated time.
A graphical or a schematic display that shows the logical
relationships and sequence of all the activities that are
required to be done in the project in the shortest possible time
frame.

Network
What is an Activity ?
Differences one can attribute to distinguish a living being from a
non-living being can perhaps lie in the word 'activity'.

From being in state 'A' to go to state 'B', we would need some kind
of force or energy to move. An activity requires physical or mental
energy.

An activity in a project is the:-

•Lowest level of effort consuming time and resources.

•Has a definable start and finish.

•Performs a part of the total work package .

In other words, to achieve work in the project it would require
performance of one or many activities.

Network
Duration of an activity:
The amount of time needed to complete an activity.
The original duration is the planned estimate, and the
remaining duration is the number of work periods to
finish activity.

Zero date :
It is the go-ahead date of a project or the date of start of a project.

Milestone :
Milestones add significant value to project scheduling which
can only be a Start type or Finish type & doesn't have any duration.

Constraint :
A Scheduling restriction you impose on the Start or Finish of an
activity. Constraints are used to reflect real Project requirement
for example all outdoor activities must be completed before the
onset of monsoon etc.

Logical relationships Network

Let us examine two activities A and B:
A is the independent activity and B is the dependent activity.
This means that A is the preceding activity and B is the succeeding
activity.
How many different types of logical combinations can there be
between the two activities A and B?

Activity A can have started or have finished. Based on these 2
possible combinations of activity A, activity B can either start or
finish as well.
This means that there can be 4 possible combinations of activity B
which is dependent on activity A.

These 4 logical combinations are shown below:

A can finish and B can start thereafter (Finish to Start).
A can start and B can start thereafter (Start to Start).
A can start and B can finish thereafter (Start to Finish).
A can finish and B can finish thereafter (Finish to Finish).

Network
Logical relationships
Finish to Start Dependency (F-S)

The independent activity A must finish before B can start.
The arrow shows the 'from to' relationship.
Generally in a project about 70 to 80% of dependency relationship is of finish-
start type.

Start to Start Dependency (S-S)

The independent activity A must start before activity B can start. The arrow
shows the 'from to' relationship.

The 'from' activity must start before the 'to' activity can start

Logical relationships Network

Start to Finish Dependency (S-F)

A must start before B can finish.

The 'from' activity must start before the 'to' activity can finish

Finish-to-Finish Dependency (F-F)

A has to be completed before B can finish.

the 'from' activity must finish before the 'to' activity can finish

Network
Lead & Lag
Lead and lag are activity relationships that are used as special modifiers to
advance or delay the succeeding activity.

Lead:
This is a modification of a logical relationship between two activities, which
allows an acceleration of the successor activity. For example, in a Finish to
Start dependency, with a 14 days lead, the successor activity can start 14 days
before the predecessor activity has finished.

A lead means that the succeeding activity will start earlier than it otherwise
would have.

Lag:
A modification of a logical relationship, which delays the successor activity.
For example, in a Finish to Start dependency, with a 14 days lag, the successor
activity cannot start until 14 days after the predecessor has finished.

A lag means that the succeeding activity will start later than it otherwise would
have.

Network
Forward Pass
The Calculation of Early dates for a project.
The Forward Pass starts from the beginning of
the Project and continues to the end to
calculate the Earliest Start and Finish dates for each
activity.

EARLY START (ES)
The date a project is scheduled to start.

EARLY FINISH (EF)
The date a project is scheduled to start.

Network
Backward Pass
The Calculation of Late dates of activities in
a network. The calculation begins with the latest
Early finish date of the last activity or the imposed
Project finish date, if one exists, and works
backwards to the first activity in the project.

LATE START (LS)
The latest start date an activity can start without
delaying the finish date of a project

LATE FINISH (LF)
The latest finish date an activity can finish
without delaying the completion of the project.

Network
FLOAT :
This is the amount of time that an activity may be delayed from its
early start without delaying the project finish date.
Float is a mathematical calculation and can change as the
project progresses and these changes are incorporated in the
project plan.
Float is the measure of the sluggishness in starting an activity.

TOTAL FLOAT (TF)
The duration of time that an activity can be delayed or extended
without delaying the project completion date.
TF = LS - ES = LF - EF,
If TF = 0, then activity is on critical path.

FREE FLOAT (FF)
It is the length of time that can delay the Early Start of an
activity without delaying the early start of a Successor activity.
It is never less than zero.

Network

Shown above is a Precedence Diagramming Method (PDM) network of 8
activities - A, B, C, D, E, F, G and H. The duration of each activity is shown
in the node.

As we go from left to right in the forward pass, let us calculate the ES and
EF of these 8 activities.

Network
Activity A

A is the first activity of the network and its duration is 1 week.
The earliest time when activity A can begin is at week 0 (zero).
Generally 0 is taken as the default start time instead of 1. In effect A will start on day
1 of week 1.
The earliest finish time (EF) = Early Start of the activity + Duration of the activity
EF = 0+1 = 1

Activity B

Network
Activity C

Activity E

Activity F Network

Activity D

Activity G Network

Activity H

Backward pass, let us calculate the LS and LF of these 8 activities. Network
Activity H

Activity G & D

Activity E Network

Final Network

Network
Bar Charts
• ADVANTAGES
Easy to prepare
Eye catching
Good for early planning
Good for small scale projects

• LIMITATIONS
Do not show relationships between activities
and hence do not illustrate project network.
Do not assist data preparation and analysis.
Do not show effects of changes or delays.

Network

Comparison between Bar-charts & Network
• Activities pertaining to a network are inter-related
with sequence, whereas bar-chart fails to
indicate clearly the interdependencies among
the various activities.

• Network can highlight the critical activities along the
critical path, whereas bar-chart cannot do the
same.

• Better & detailed planning is possible with the help of
network.

• Float ( Slack time ) in each activity can be
achieved from network analysis, which in turn helps
in judging the criticality of the activities. This type
of control measure is not possible in a bar-chart.

PERT
Program Evaluation and Review Technique
The consultants, Booz-Allen & Hamilton developed the concept of
PERT while supporting the Polaris program.

They came out with the concept of using a 3 time weighted
estimate to determine the duration of an activity instead of the
single time estimates that was in use.

This concept was especially useful for those activities where
uncertainties were of a high degree.

The 3 time estimates used in Program Evaluation and Review
Technique (PERT) system considers the following three aspects:

Optimistic (O) duration estimate for completing an activity

Most Likely (ML) duration estimate for completing an activity

Pessimistic (P) duration estimate to complete an activity.

PERT

Estimated Duration Time Estimate for an activity is:

[1 x Optimistic duration estimate + 4 x Most Likely duration estimate +
1 x Pessimistic duration estimate] / by 6

Estimated Duration of an activity = [Optimistic + 4 x Most Likely +
Pessimistic] / 6

My Optimistic time for commuting is 30 minutes; Most Likely time for
commuting is 40 minutes; Pessimistically speaking, it may take upto 70
minutes in the worst scenario of traffic jams etc.

Using the 3 time estimates of PERT method, the Estimated time for this
activity is:

[30 minutes + (4 x 40 minutes) + 70 minutes] / 6 which come to 43.3
minutes.

CPM
Critical path
• The critical path is the longest path in the network and shows
the earliest date by which the project can be completed.
There can be more than 1 critical path in the project .

• An activity is critical if the total float is equal to zero.

• Any delay in start or completion of the critical path activities
delays the overall project completion.

To arrive at the project's critical path we must have a list of:

• All the activities required to complete the project

• The time duration of each activity

• The dependencies between these activities

Critical path CPM

Let us look at the example we have covered earlier of a project
network comprising of 8 activities from A to H. The critical Path in
this example had 4 activities A, E, G and H.

The total project duration as per our network calculations came to
20 weeks

S-Curve
A Sample Monthly Progress Report
Progress reporting is done through different formats and curves.

31

S-Curve
What is “S Curve”

S- Curve is the graphic display of cumulative progress
plotted against time.

Ideal S - Curve is a sinusoidal curve based on the
following formulae:
Y = [1 - sin(x/xn*180 + 90 ) *50]

Y – Percent progress
x – Period at which s-curve value required
xn – Total period

The name is derived from the 'S' like nature of the curve.

“S Curve” or Project Life Cycle S-Curve

S-Curve
Progress distribution curve

Peak Period

Cumulative progress Curve
Plotted in a different scale
Progress

Starting Period Finishing Period

Time
It is an ideal distribution curve. Depending upon the various
guiding factors it may vary.

S-Curve

Note :
Previous distribution is an ideal
one. Depending on nature and
location of job this distribution
may vary. The experience of
concerned project manager will
play a vital role in deciding the
projected distribution of progress
of any activity during its span of
implementation.

• MSP is a Project Management (PM)tool .

• Gantt Chart is famous Toolbar in MSP.
• Left side of Gantt Chart window shows the Activities with
relations
•Right side of Gantt Chart shows the timescale & Bars with
relationships.

Let us consider an example :

Construction of House using MSP Software

Project network scheduling and S-curve

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