CONSTRUCTION MANAGEMENT

2.4.2.2 CONSTRUCTION STAGE

Description of Management Arrangement
project of the work for controlling

significant
site risk

The Health
and Safety

File

Figure 2.7: Construction stage Plan

1. Description of Project
a) Project Description and program details including key

dates
b) Details of clients, principal designer, designers, and

other consultants
c) Extent and location of existing records and plans that

are relevant to health and safety on site, including all
information about the existing structures when
appropriate

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /40

2. Management of the work

a) Management structure and responsibilities
b) Health and safety goals for the project and arrangements

for monitoring and review of health and safety
performance
c) The arrangement is for:
➢ Regular liaison between parties on site
➢ Consultation with the workforce
➢ Exchange of design information between the client,
principal designer, designers, and contractor on site
➢ Handling design changes during the project
➢ The selection and control of contractors
➢ The exchange of health and safety information between
contractors
➢ Site Security
➢ Site induction
➢ On-site training
➢ Welfare facilities and first-aid
➢ The reporting and investigation of accidents and incidents
including near misses
➢ The production and approval of risk assessments and
written systems of work
➢ Site Rules
➢ Fire and emergency arrangement

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /41

3. Arrangement for controlling significant site risks

a) Safety risk:

➢ Deliveries and removals of materials, waste, and work
equipment must take into specific any risks to the public, such as
those present during site access and egress.

➢ Dealing with services such as water, and electricity, including
overhead power lines and temporary electrical installations

➢ accommodating the usage of nearby land
➢ Stability of structures whilst carrying out construction work,

including temporary structures and existing unstable structures
➢ Preventing falls
➢ Work with or near fragile materials
➢ Control of lifting operations
➢ The maintenance of plant and equipment
➢ Work on excavations and work where there are poor ground

conditions
➢ Work on or near water where there is a risk of drowning
➢ Work on wells, underground earthworks, and tunnels
➢ Work involving diving
➢ Work caisson or compressed air working
➢ Work involving explosives
➢ Traffic routes and segregation of vehicles and pedestrians
➢ Storage of materials(particularly hazardous materials and work

equipment
➢ Any other significant safety risks

b) Health risks:
➢ the removal of asbestos
➢ Dealing with contaminated land
➢ Manual handling
➢ use of dangerous materials, especially when health monitoring is

required
➢ Reducing noise and vibration
➢ working with radiation or exposing oneself to any other serious

health concerns

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /42

4. The Health and Safety File
a) Layout and format
b) Information collecting and collation arrangements
c) Storage of information

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /43

2.4.2.3 POST-CONSTRUCTION STAGE

At the end of the project:
a) The Health and Safety File must therefore be delivered to the

client upon project completion. And should be kept by the client
so that anyone performing work in the future will have the
knowledge they need to plan and accomplish the work safely.
b) The facility or structure is turned over to the client and typically
involves working in occupied spaces during a period of defects
liability. Depending on the facility/structure, it could also involve
putting management and plant equipment into operation. A
phased handover is used in some projects, where one portion of
the building or facility is operational before another that is still
being built. During this phase, the client may transfer ownership
of the building or structure to the occupier, who will be in charge
of running it and keeping it maintained.
c) Design considerations for the facility's or structure's safe
operation, including upkeep, servicing, cleaning, and facilities
management, will have been made. Access for internal and
external maintenance and cleaning, floor surfaces, the removal of
manual handling, storage areas, fire evacuation, disability access,
security systems, and access are design problems that can
enhance safety. An evaluation of the entire construction project
process should be done at this time to determine whether any
lessons can be learned and incorporated into safety management
procedures for upcoming projects.

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /44

2.4.3 METHODS TO INCREASE CONSTRUCTION SITE
SAFETY

The following fundamental ideas serve as the
starting points. These guidelines' actions are meant to be
supported by these concepts, which will result in good
health and safety performance to increase construction site
safety.

Strong and • Visible, active commitment from
active the Board

leadership • Establishing effective ‘downward’
from top communication systems and
management management structures

• Integration of good health and
safety management with business
decisions

Worker • Engaging the workforce in the
involvement promotion and achievement of safe
and healthy conditions

• Effective ‘upward’ communication
• Providing high quality training

Assessment • Identifying and managing health and
and review safety risks

• Accessing competent advice
• Monitoring, reporting and reviewing

performance.

CHAPTER 2 : CONSTRUCTION SITE MANAGEMENT /45

CHAPTER 3 :
PLANNING TECHNIQUES

IN CONSTRUCTION
PROJECT

3.1 IMPORTANCE OF PLANNING TECHNIQUES IN
CONSTRUCTION PROJECT

Construction project planning is important for the
success of a construction project to ensure: -

1) Work is better and guaranteed in quality
2) More effective communication system
3) Construction site's management is more structured
4) More effective in time management
5) More effective task management and enhanced

business skills

To guarantee that project planning is successful, a
variety of planning strategies are used. A planning technique
is a communication document that specifically lists the
tasks that must be carried out in order to stick to the
timeline that has been set. All parties involved in the
construction project will use this document as their primary
source of reference.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /47

Therefore, the planning technique must meet all of the
following requirements;

1) Easy to understand
2) Can meet the requirements of all involved parties
3) Provide a standard framework
4) Can be used as a guideline for the implementation

of work, and
5) Can be applied for monitoring and controlling

purposes.

The construction sector employs several planning
techniques, such as the following;

1) Bar Chart
2) Critical Path Method (CPM)
3) Program Evaluation and Review Techniques (PERT)
4) Line Balance (LoB)
5) S-Curve

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /48

3.2 BAR CHART

3.2.1 Usage of Bar Chart

The planning technique that most frequently used to
schedule construction projects is a bar chart, also known as
a Gantt chart as Henry Gantt is the name of its inventor. Bar
charts are widely used because they are straightforward to
create and easy for readers to understand. On the left is a
list of the duties, and at the bottom are the construction
times, which are counted from left to right. The construction
time for each action is displayed as a bar. The tasks for a
project are shown along with their due dates and anticipated
completion dates in a bar chart. The tasks that have been
finished are indicated by coloured bars as the project moves
along. The scheduling technique that is easiest to use also
happens to be the fastest. Clients, designers, and industry
professionals in construction regularly use it.

When should you use a bar chart? The bar chart will be
used to:

1) Scheduling and tracking tasks within a project.
2) Providing project plans or updates.
3) The project or process's steps, their scheduling,

and their duration are known.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /49

Before any parties in a building project start working, a
bar chart is always necessary. At the pre-tender stage, an
estimator requires a bar chart to determine the tender price.
The estimator can see each task and its completion dates
through the bar chart. The overhead costs can be calculated
based on the completion time of the entire project.

At the post-tender stage, the site manager needs a bar
chart to know the sequence of task to execute. The bar chart
shows that all the resources needed, including plants, labor,
and materials, can be provided at the required time. Most
importantly, the usage of bar charts is to track task
progress. Below the planned bar, draw a bar representing
the actual work execution. That way, we can compare the
actual start and completion date to the planned date. If there
is a delay, immediate action needs to fix it. Investigating the
cause of the delay, talking with the affected construction site
workers, and coming up with a solution are all immediate
actions. The conditions of the contract include provision for
delays resulting from unforeseen circumstances like bad
weather, floods, a lack of materials on the market, and
others. In this case, the contractor can propose an extension
of time for the project's completion.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /50

On the other side, the contractor is responsible for
delays brought on by poor project management. To expedite
work progress, steps like expanding the number of plants
and employees or putting in extra hours are necessary.

The design of work plans like bar charts will not aid
management without the required supervision. The bar
charts should be used as an effective tool and continually
reviewed.

3.2.1 Procedure in Preparation of Bar Chart
There are several steps involved in creating a bar chart
as follows: -

STEP 1 Identify tasks

• Identify the tasks required to complete the project.

• Identify the milestones for each task by making a list,
creating a flowchart storyboard, or creating an arrow
diagram.

• Identify the time required for each task.

• Identify the sequence: Which tasks must be finished
before a following task can begin, and which can happen
simultaneously.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /51

STEP 2 Draw axis

• On a page, illustrate a horizontal time axis at the top or

bottom.

• Mark it off using a scale that is appropriate for the volume

of work (days or weeks).

STEP 3 Write task

• Write each project task and milestone down the left side of

the page in the correct order.

• According to the time scale, create a coloured horizontal

bar for each task. This is shown as planning bars.

• For the purpose of tracking future job progress, illustrate an

empty bar beneath each coloured bar. This is shown as

actual bars.

STEP 4 Checking

• Check that every task of the project is on the chart.

• As events and activities take place, shade the empty bars

to show completion.

• Place a vertical marker to indicate where you are on the

timeline. For instance, if the chart is hung on the wall, a

simple method to display the time is to hang a thick, dark

string vertically across the chart using two thumbtacks.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /52

The project is structured into tasks or activities
depending on the type of work sequence. For the
masterwork program, the work is breakdown into massive
activities such as piles, foundations, columns, beams, and
slabs. For short-term programs, work is breakdown into
more detailed activities such as excavation, formwork,
reinforcement, and concrete. While for the weekly program,
the activities consist of tasks that need to be carried out by
specific groups of excavation, concrete work, and removing
the formwork.

To complete a project for a specific activity, the project
manager must have broad knowledge and extensive
experience to determine the duration of each activity by
using available resources.

Employ the construction of a pad foundation as a simple
example of producing a bar chart. The construction of the
pad foundation is breakdown into five activities in the
sequence shown in Table 3.1.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /53

The next steps are as follows:
1) Illustrate an x-axis (horizontal line) showing the

timeline for project completion. The scale unit are
based on the type of work program, whether it is
days, weeks, or months. In this example, the unit
used is days.
2) Illustrate the y-axis (vertical line) on the left side
and list all the activities.
3) Illustrate a colored horizontal bar (black or other
colors) for each activity according to the time scale.
4) Illustrate another empty bar under each colored
bar for monitoring work progress in the future.
(refer Figure 3.1)

Table 3.1: Construction of pad foundation

Activities Duration (days)
Plotting 2
Excavation 4
Formwork 4
Reinforcement 2
Concrete 2

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /54

Activities Duration (days)
Plotting 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Excavation

Formwork

Reinforcement

Concrete

Figure 3.1: Bar chart for construction of pad foundation

3.2.3 Advantages and Disadvantages of Bar Chart

The advantages of bar charts that make it the most
popular technique are as follows:

1) Easy to prepare and easy to understand.
2) Show a clear visual representation of the work's

progress and timeliness also can be used in the
preparation of the S-curve.
3) It is easily adaptable to project changes.
4) Management is aware of it because it does not
require technical knowledge to be understood.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /55

Although a bar chart is easy to prepare and understand,
this technique has some disadvantages. The disadvantages
of bar charts are as follows:

1) It suitable for small projects. Large projects can
make it practically impossible to read and highly
complex.

2) There is no interaction between the activities.
3) For every non-small project, printing the Gantt

chart on a page, even a big one, is practically
impossible. Most project managers have to
overcome this issue by scotch tape the Gantt chart
together after printing it on various pieces of paper.

Therefore, linked bar charts were introduced to meet
this weakness. However, the linked bar chart technique is
not very popular and rarely used. On the other hand, the
critical path method is an increasingly popular technique.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /56

Although a bar chart is easy to prepare and understand,
this technique has some disadvantages. The disadvantages
of bar charts are as follows:

1) It suitable for small projects. Large projects can
make it practically impossible to read and highly
complex.

2) There is no interaction between the activities.
3) For every non-small project, printing the Gantt

chart on a page, even a big one, is practically
impossible. Most project managers have to
overcome this issue by scotch tape the Gantt chart
together after printing it on various pieces of paper.

Therefore, linked bar charts were introduced to meet
this weakness. However, the linked bar chart technique is
not very popular and rarely used. On the other hand, the
critical path method is an increasingly popular technique.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /57

3.3 CRITICAL PATH METHOD (CPM)
The critical path method is a technique used to enable a

project to be planned and controlled through a better
understanding of the entire project. The CPM is based on a
logical network with a diagram drawn using certain
symbols. A logical network diagram is a network of activities
for project implementation arranged in a logical sequence.

The critical path is the lengthiest set of tasks to be
completed in a project from start to finish. The tasks on the
critical path are known as critical activities. The entire
project will delay if they get behind schedule. By identifying
and calculating the critical path, we can determine the total
duration of a project and the critical activities that must
complete on time. Once a critical path is determined, there is
a clear picture of the project’s actual schedule.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /58

3.3.1 Usage of CPM
The CPM will be used to:
1) Identify the task required to complete the project

and the dependencies between each other.
2) Calculate how long each project task will take.
3) Determine the critical activities by calculating the

critical path based on the task duration and
dependencies.
4) Focus on planning, scheduling, and controlling
critical activities.
5) Establish timeframes for the expectations of
stakeholders

3.3.2 Term of CPM
The first step in a critical path method is to create a list
of activities and their dependencies. After that, the next step
is to create a network diagram. A project network diagram
shows the logical sequence of the tasks. It displays the
order of the activities from start to finish. There are
essentially two methods used to draw network diagrams.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /59

There are essentially two methods used to draw
network diagrams. These methods are the Arrow
Diagramming Method (ADM) or Activity On Arrow (AoA) and
Precedence Diagram Method (PDM) Activity on Node (AoN).
Both, will enable us to identify the project's critical path.

The network diagram will use three symbols as follows:
1) Arrow

Arrow symbols indicate activities that require time
and other resources. Arrows are drawn not to
scale. The name of the activity is on the arrow,
and the arrowhead denotes when an activity ends.
2) Nodes
Nodes symbols indicate the activity that shows it's
duration and intersections where activities begin or
end. The activity at the arrowhead must be greater
than the activity number, which is the earliest and
the latest time.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /60

3) Dashed Arrows
Dashed arrow symbols indicate a dummy activity. A
dummy activity is an activity that is added to show
dependencies between activities but is not an actual
activity. It is to retain the proper sequence or to
divide tasks into independent ones. A dummy task
often has zero duration.

For better understanding, the network diagram will be
explained in the Arrow Diagram Method and Precedence
Diagram Networks respectively.

3.3.3 Arrow Diagram Method (ADM)
As mentioned previously, ADM is also known as Activity
on Arrow. ADM is composed primarily of arrows and nodes.
One activity is represented by one arrow. The activity's
beginning and ending points are represented by the arrow's
starting and ending points, respectively. The length of the
arrow indicates the activity's duration and ADM only shows
finish to start (FS) relationship between the activities. Figure
xxx show the example of ADM.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /61

Figure 3.2: Example of Arrow Diagram Method

Figure 3.2 show the example of ADM. The nodes of this
network system are represented by circles 1, 2, 3, and 4 and
possess no resources and duration. The arrows represent
the following activities: A, B, C, and D. There is a duration and
a resource allotted for each activity. Activity A and B start
simultaneously. Should be activity C cannot begin until
activity A completed. Activity D also cannot start until activity
B is completed. But, there is dummy activity between nodes
2 and 3. So activity C can start the work after activity A
completed, while activity D only can start after activities A
and B are ready. The dummy activities are to distinguish two
activities so that they do not have the same event number.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /62

3.3.4 Preparation of ADM
To prepare the ADM, follow these instructions;

STEP 1 Identify activities
• List all the activities that need to complete the project.

STEP 2 Calculate the activity durations

• Calculate the activity durations considering the crews and
the amount of work.

• The activity durations will affect the length of the critical
path, hence estimate the activity durations is a crucial step.

• There are methods for calculating activity periods as an
expert assessment, analogous estimating, parametric
estimating, and three-point estimating. The three-point
estimating is use in Program Evaluation Review Techniques
(PERT). We will discuss on this later.

STEP 3 Identify the logical sequence
• Identify the logical sequences, predecessor, and successor

activities.
• Use the ADM when carrying out this step to answer the

following questions; which task will begin first?, what
activities will start simultaneously?, which task will end
immediately following this one?, and what task will begin
right after this one?

STEP 4 Illustrate the network diagram

• Draw the nodes for the activities that mark the start and
finish of such an activity. These nodes divide up the many
activities.

• Use dummy activity if necessary, and display them as
dashed lines

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /63

STEP 5 Calculate the critical path

• Calculate the critical path of the network diagram by using
forward pass and backward pass techniques.

• The forward pass (from left to right) is a technique where
we can find out the earliest event time, while the backward
pass (from right to left) is where we can find the latest
event time of each activity.

STEP 6 Calculate the Total Float and Free Float

• Also known as slack.
• Total float is the amount of time can of an activity can be

delayed without delaying the project's duration. Total Float =
LS - ES or LF -EF.
• Free float is the amount of time that a task can be delayed
without affecting the ES of the succeeding activity. Free float
= ES(next task) - EF (current task).

STEP 7 Identify the critical activities and critical path
• The critical activity where the total float is 0.
• The critical path is path of the critical activities.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /64

Let's look at the example based on Table 3.2. The
following data have 8 activities from A to H with their events
and durations of each activity next to them.

Table 3.2: Activities, Events and Durations of a project

Activity Events Durations
(days)

A 1-2 2

B 2-3 3

C 2-4 4

D 3-4 dummy

E 3-5 3

F 4-6 6

G 5-7 4

H 6-7 5

From the Table 3.2, we can illustrate the ADM such in
Figure 3.3.

Figure 3.3: The network diagram of ADM

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /65

From the Figure 3.3, the ADM is illustrate based on the
information in Table 3.2. We can see that the nodes
represents by the events number and the activity with the
durations in the bracket are on the arrows. The duration for
activity D is 0 because it is a dummy activity. Now, lets we
calculate the critical path by using forward pass first as in
Figure 3.4.

Figure 3.4: The forward pass technique in calculating the
critical path in ADM

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /66

The forward pass calculation is from left to right, draw
two boxes that represent Earliest Start (ES) at the top and
Late Start (LS) and the bottom. To calculate the ES, take the
Early Finish (EF) of the previous node and adding with the
duration of the current activity.

In Figure 3.4, assume that the ES at nodes 1 is zero (0)
as there no task before it. At nodes 2, the ES is 2 days as the
EF of previous nodes is 0 and the duration of activity is 2
days, so that 0 + 2 is equal to 2 days. This means, the ES of
activity A is O and EF is at day 2. The ES of the next activity
can be calculated in the same way.

See at the events 2-4 and 3-4 which is activity C and D
respectively, activity C have 4 days duration and activities D
is a dummy activity, so that it does not have any durations.
At nodes 4, the ES will be 6 days instead of 5 days because
we must take the biggest number to make sure all the
activities can be completed. That is the same situation at
nodes 7 also the last task of the project, the ES is at day 17.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /67

Next, let’s do the backward pass calculation as in Figure
3.5, which is from right to left, at this techniques we want to
find out the LS. To calculate the LS, take the Late Finish (LF)
of the previous activity and subtracting by the duration of the
current activity.

Figure 3.5: The backward pass technique in calculating
the critical path in ADM

In figure 3.5, the ES at nodes 7 will be used as the LS of
the project. That is also shows the total duration of the
project is 17. The LS at nodes 6 is 12, which is subtracting
the LF at nodes 7 with the duration of activity H. 17 – 5 days
is equal to 12.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /68

The LS of the next activity can be calculated in the same
way. If there are two or more different numbers, choose the
smallest number to give all activities sufficient time as at
node 2, the LS is 2 instead of 3.

Then, calculate the total float to identify the critical
activities. To calculate the total float, subtracting the LS with
ES. The total float that is equal to zero is the critical activity
and the critical path involves all the critical activities. That
means those activities cannot be delayed at all to make sure
it will not affected the total duration of the project.

Figure 3.6: The total float of each activity

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /69

In Figure 3.6, we can conclude that events 1-2-4-6-7 is
the critical path and the critical activities are A, C,F, and H as
all the total floats are 0. These activities must start as soon
as the completion of previous activity. The completion time of
the activity must not exceed the specified period. Therefore,
more attention needs to be given to activities in critical path.

While, activity E in the event 3-5 and activity G in the
event 5-7 is not in the critical path. Activity E can be delayed
by 1 day and activity G can be delayed by 5 days without
affecting the total duration of the project.

In the past, the ADM approach contributed to network
diagrams to determine the critical path. Currently, ADM is
no longer employed, and Precedence Diagram Method (PDM)
has been used to generate network diagrams.

3.3.5 Precedence Diagram Method (PDM)
PDM is also known as Activity on Nodes. PDM is a
different type of network diagram where activities are
represented by nodes and linked to one another by arrows.
These arrows show the linkages between various activities.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /70

All four relationships between activities were present
by using the PDM. These are Finish to Start (FS), Start to
Start (SS), Finish to Finish (FF), and Finish to Finish (SF)
relationships as shown in Figure 3.7.

Figure 3.7: Relationship between activities in PDM

3.3.6 Preparation of PDM
The preparation of PDM in the determination of critical
activities and critical path is almost the same steps with
ADM, But there is slightly difference in the network diagram
illustration. Let's look at how to illustrate the network
diagram, in PDM. The data in Table 3.3 has 6 activities from A
to F. Each action has predecessors listed next to it.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /71

Table 3.3: Activities and predecessor of a project

Activity Predecessor Duration
A - 1
B A 2
C A 1
D B 6
E C 2
F D,E 7

To illustrate the network diagram of PDM, initially,
create a box to symbolize activity A. Then, draw two boxes
for B and C and connect them to activity A because B and C
both have a precursor in the form of A. Draw boxes for D
and E and link them to activities B and C, respectively.
Lastly, create a box for activity F and link it to activities D
and E. Refer to Figure 3.8 for better understanding.

Figure 3.8: The network diagram for PDM

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /72

Figure 3.9: ES, LS, EF and LF in PDM

The next step is draw 6 six small boxes at each box of
activity. The six boxes consists of ES, LS, EF, LF, label of
activity and it’s durations as in Figure 3.9. To determine the
critical path, use the pass forward method. Here, we will get
the ES and EF for each activity. This is shown in Figure 3.10.
The ES is the EF in previous activity. The EF is summation of
ES and duration of the activity. In Activity A, the ES will be 0
as there no activity before it while the EF is 1 (0+1 = 1). In
Activity B, the ES is 1, as the previous Activity is A and the EF
is 1, so the EF for activity B is 3 (1+2 = 3). The ES and EF for
others activity will be use the same technique as in Figure
3.10.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /73

Figure 3.10: The forward pass technique in calculating
the critical path in PDM

If there have two or more difference number between

the activities, take the biggest number, same as in ADM.

Now, we find out the LF and LS using the backward

pass, from right to left. The LF is the LS of previous activity

while LS is the LF – duration of current activity. In figure 3.11,

the LF for Activity F is 16 as it is the last activity of the

project. The LS for Activity F is 9 (16-7 = 9). In Activity E, the

LF is 9 as the LS of previous activity, which Activity F is 9.

The LS for Activity E is 7 (9-2 =7). If there have two or more

difference number between the activities, take the smallest

number. CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /74

Figure 3.11: The backward pass technique in calculating the
critical path in PDM

Then, find out the total float and the critical path same
as in the ADM. In Figure 3.12 we can conclude that the critical
activities are A, B, D, and F and the critical path is A-B-D-F.
Activities C and E respectively have 5 float time, this means
these activities can be delayed by 5 days.

In conclusion, ADM and PDM are the two main
categories of network diagramming techniques used in the
Critical Path Method. The ADM represents the activities with
arrows and the PDM displays the activities as nodes or
boxes. The PDM is simple to use and can handle schedules
of any complexity.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /75

Figure 3.12: The total float of each activity in PDM

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /76

3.4 PROGRAM EVALUATION AND REVIEW
TECHNIQUES (PERT)

PERT, also known as the Program Evaluation
Review Technique, is a visual tool for project planning. The
method makes it easier for project planners to determine
the start and finish dates also the interim tasks and
deadlines. The data is shown as a network in a chart. It was
created by the US Navy in 1958 and is frequently used in
conjunction with the CPM, which was first introduced in 1957.

3.4.1 Usage of PERT
The purpose of PERT is to simplify large and complex
project planning and scheduling. It is a method for
examining each activity necessary to complete a specific
project. A prime example is the 1968 Winter Olympics in
Grenoble, which used PERT from 1965 until the start of the
Games in 1968.
By using a weighted average of optimistic and
pessimistic scenarios, PERT is used to estimate the degree
of uncertainty around project activities. It assesses how
long it takes to finish a task.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /77

PERT assists the project manager in:
1) Identify the start and finish dates.
2) Estimate the time for the entire task to be completed.
3) Every action that affects the completion time is

referred to as an event on the chart.
4) Identify the sequence of activities.

3.4.2 Preparation of PERT
PERT examine the schedule's tasks by identifying a
Critical Path Method (CPM) which is calculate the critical
activities and floats. The minimum amount of time needed to
finish a project is calculated by looking at the length of time
needed to accomplish each task and any dependencies that
go along with it. It calculates how long each activity will
probably take, how long it will probably take, and how long it
might take if it takes more time than expected.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /78

PERT has identified four different categories of time
needed to complete an activity:

Optimistic • The minimum amount of time needed,
Time (o) provided everything works better than
Pessimistic is frequently expected, to complete a
Time (p) task.
Most Likely
Time (m) • The length of time needed to complete
a work at its most optimistic, provided
nothing goes wrong (excluding major
catastrophes).

• The most accurate calculation of the
time needed to complete a task,
presuming everything goes according
to plan.

Expected • The best calculation of the duration of
Time an activity (te) or a path (TE), taking
into account that things don't always go
according to plan.

• The formula = o + 4 +
6

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /79

The example of three - times estimates as in Table 3.4.

Table 3.4: Example of three-time estimates

Task Optimistic Time Most Likely Pessimistic
(o) Time (m) Time (p)

A 2 weeks 4 weeks 5 weeks

B 1 week 2 weeks 3 weeks

C 2 weeks 3 weeks 4 weeks

D 3 weeks 5 weeks 8 weeks

Completion 8 weeks 14 weeks 20 weeks

The steps to produce the PERT as follows:

STEP 1 Calculate the time estimate (te)

• Using the formula, calculate the time estimate of each
activity.

STEP 2 Identify the logical sequence and network
diagram

• Identify the logical sequences, predecessor, and successor
activities.

• Draw the nodes for the activities that mark the start and
finish of such an activity.

STEP 3 Calculate the critical activities and critical
path

• Calculate the critical activities of the network diagram by
using forward pass and backward pass techniques.

• Calculate the total float and identify the critical path

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /80

Let's look at the example based on Table 3.5. The
following data have 10 activities from A to J with their
predecessor and three-time estimates of each activity next
to them. The first thing to do in PERT is find out the time
estimate (te) by using the formula below :

o + 4 +
6

Table 3.5: Activity, Predecessor and three-time estimates
of a project

THREE-TIME ESTIMATES (WEEK)

ACTIVITY PREDECESSOR Optimistic Most Likely Pessimistic
Time (o) Time (m) Time (p)
A - 6 7
B - 5 3 5
C - 1 4 7
D A 1 2 3
E B 1 2 9
F C 1 5 9
G C 1 2 8
H E,F 2 4 10
I D 4 5 8
J G,H,I 2 2 8
2

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /81

The time estimate of all activities are shown in Table
3.6.

Table 3.6: The Time Estimate (te) of a Project

THREE-TIME ESTIMATES (WEEK) TIME
ESTIMATES (te)
ACTIVITY Optimistic Most Likely Pessimistic
Time (o) Time (m) Time (p) o + 4 +
A 6 7 6
B 5 3 5
C 1 4 7 6
D 1 2 3 3
E 1 2 9 4
F 1 5 9 2
G 1 2 8 3
H 2 4 10 5
I 4 5 8 3
J 2 2 8 5
2 5
3

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /82

Then, illustrate the network diagram. It is more easier
if use PDM to create the network diagrams as shown in
Figure 3.13. Activities A, B, and C are start simultaneously
and there is no other activities before them.

Figure 3.13: Network Diagram of a Project

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /83

Next, calculate the critical activities, this is the same
techniques in CPM by using forward pass and backward
pass. In Figure 3.14, the critical activities are C,F,H and J
and the critical path is C-F-H-J. The expected completion
time is 17.

Figure 3.14: The Critical Path of a Project
From the example we can conclude that CPM and PERT
are almost use the same techniques. But, there are still
have differences between these method. Check the
difference in Table 3.7.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /84

Table 3.7: PERT versus CPM

PERT CPM

PERT is that technique of CPM is that technique of

project management which is project management which is

used to manage uncertain used to manage only certain

time of the activities of any times of the activities of any
project. project.

It is a probability model. It is a deterministic model.

It majorly focuses on time as
meeting time target or It majorly focuses on time-
estimation of percent cost trade off as minimizing
completion is more cost is more important
important.

It is appropriate for high It is appropriate for
precision time estimation. reasonable time estimation.

It has non-repetitive nature It has repetitive nature of job.
of job.

There is no chance of There may be crashing
crashing as there is no because of certain time
certainty of time. based.

It doesn’t use any dummy It may uses dummy activities
activities. for representing sequence of
activities.

It is suitable for projects It is suitable for construction
which required research and projects.
development.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /85

3.4.2 Advantages and Disadvantages of PERT

The advantages of PERT as follows:

Evaluate time Visibility of Analysis of
and resources Critical Path in Activity in

PERT PERT

It provides the The PERT The activity and
program method will the events are
managers show the analysed from
information to critical path in the PERT
evaluate time a well-defined networks.
and resources manner.
on a project

The critical These are
path is the path analysed
with activities independently as
that cannot be well as in
delayed under combination.
any This will give a
circumstances. picture about the
likely completion
of the project and
the budget.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /86

The disadvantages of PERT as follows:

Time Focused Subjective Complicated
Method Analysis in Charts

• The method of PERT • PERT charts
PERT is a can be
time-oriented • The activities complicated
method, where for a project and confusing,
the time are identified with hundreds
required to based on the or even
complete the data available. thousands of
respective tasks and
activity is of • This is difficult dependency
higher in case of relationships.
importance. PERT as these
are mostly • This is
• Hence the applied for a especially true
time project that is of very large
determination newly projects. PERT
of each conducted or diagrams can
activity and its those without be expensive
allocation is repetitive to develop,
very much nature. update and
necessary. maintain.
• The project
dealt by PERT
will be fresh
project data
that make the
collection of
information to
be subjective
in nature.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /87

3.5 LINE OF BALANCE (LoB)

Line of Balance (LOB) is one of management control
technique that gather, assess, and present information on
time, cost, and accomplishment that is compared to a
particular plan. The goal of a LOB is to make it possible for a
project manager to quickly determine which operations'
activities are "in balance," or whether those that should
have been finished at the time of the review were and
whether any activities with future completion dates are
running behind schedule.

The LoB graph consists of an inclined straight line, one
line for one activity. The slope of each line shows the
different construction rates for each activity. Therefore, this
method will show the relationship between the balance in
allocating resources with the rate of construction to avoid
clashes between activities. Buffer time is an extra time at
the end of an activity is added to deal with any possibility of
delay. With that, any delay that occurs in an activity will not
interfere with the time of the next activity.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /88

3.5.1 Usage of LoB
The LoB shows the process, status, background, timing,
and phasing of the project activities, thus providing
management with measuring tools that help:
1) Assessing changes over time in relation to a defined

objective plan.
2) Focusing on the deviations from the original plans

and evaluating their seriousness in relation to the
remaining work on the project.
3) Receiving timely information about trouble spots and
identifying regions that need the appropriate
corrective action.
4) Predicting future performance.

CHAPTER 3 : PLANNING TECHNIQUES IN CONSTRUCTION PROJECT /89