GWALIOR INSTITUTE OF INFORMATION TECHNOLOGY (GIIT)
MAHARAJ PURA NEAR MILITARY AREA
GWALIOR (M.P)
CE-802-: construction planning & mangement-
Prepared by: Er. Satish kumar ahirwar
Mob. 9584834411
Email.: satish0946@gmail.com
Unit -1
 Modern management techniques- CPM/PERT with network analysis :Que.1 Discuss the historical background of CPM & PERT ?
Ans.1 Cpm & Pert techniques have their origin from (1958 to 1960) in two parrallel
but different problems of planning and controlling projects in U.S.A.
CPM/PERT or Network Analysis as the technique is sometimes called, developed
along two parallel streams, one industrial and the other military.
CPM was the discovery of M.R.Walker of E.I.Du Pont de Nemours & Co. and J.E.Kelly
of Remington Rand, circa 1957. The computation was designed for the UNIVAC-I
computer. The first test was made in 1958, when CPM was applied to the
construction of a new chemical plant. In March 1959, the method was applied to a
maintenance shut-down at the Du Pont works in Louisville, Kentucky. Unproductive
time was reduced from 125 to 93 hours.
PERT was devised in 1958 for the POLARIS missile program by the Program
Evaluation Branch of the Special Projects office of the U.S.Navy, helped by the
Lockheed Missile Systems division and the Consultant firm of Booz-Allen &
Hamilton. The calculations were so arranged so that they could be carried out on
the IBM Naval Ordinance Research Computer (NORC) at Dahlgren, Virginia.
Que.2 Discuss planning ,scheduling & controll ?
Ans.2 Planning, Scheduling (or organising) and Control are considered to be basic
Managerial functions, and CPM/PERT has been rightfully accorded due importance
in the literature on Operations Research and Quantitative Analysis.
Far more than the technical benefits, it was found that PERT/CPM provided a focus
around which managers could brain-storm and put their ideas together. It proved to
be a great communication medium by which thinkers and planners at one level
could communicate their ideas, their doubts and fears to another level. Most
important, it became a useful tool for evaluating the performance of individuals and
teams.
There are many variations of CPM/PERT which have been useful in planning costs,
scheduling manpower and machine time. CPM/PERT can answer the following
important questions:
How long will the entire project take to be completed? What are the risks involved?
Which are the critical activities or tasks in the project which could delay the entire
project if they were not completed on time?
Is the project on schedule, behind schedule or ahead of schedule?
If the project has to be finished earlier than planned, what is the best way to do this
at the least cost?
Que.3 Advantages & Limitations of CPM & PERT network ?
Ans.3 following are the advantages and limitation of CPM & PERT given below :
Ø Advantages of PERT/CPM
1. Especially useful when scheduling and controlling large projects
2. Straightforward concept and not mathematically complex
3. Graphical networks help to perceive relationships among project activities
4. Critical path and slack time analyses help pinpoint activities that need to be
closely watched
5. Project documentation and graphics point out who is responsible for various
activities
6. Applicable to a wide variety of projects
7. Useful in monitoring not only schedules but costs as well
Ø Limitations of PERT/CPM
1. Project activities have to be clearly defined, independent, and stable in their
relationships
2. Precedence relationships must be specified and networked together
3. Time estimates tend to be subjective and are subject to fudging by managers
4. There is an inherent danger of too much emphasis being placed on the longest
or critical path
Que.4 Define and discuss various elements of network ?
Ans. 4 the element of networks areas follows :1. Activity:- an activity is the performance of a specific task such as bending of
reinforcement , placing of concrete,. Etc. it requires time & resourses for its
completion & is represented by an arrows.
‘‘Concreting’’
2. Event:- event (is also called ‘nodes’) represent instant in time when certain
activity has been started or completed . in other words ‘Event describes start
or completion of task. Or it is represented by an circle .
‘ Activity’
i- node
j- node
3. Dummy:- a dummy is an artificial activity represented on the arrow dig. By
dotted arrow . it doesn’t requires any time or resourses.
A
b
c
dummy
4. Network :- this is an arrow dig. Consisting only arrow and circle drawn to
represent the inter relationship and sequences of all the required construction
activity of a project . Network analysis is the general name given to certain
specific techniques which can be used for the planning, management and
control of projects.
node
Activity
5. Node :- A node is represented by a circle
Que .5 what do you mean by the PERT event & also predecessor events and
successor events ?
Ans .5 PERT event: a point that marks the start or completion of one or more
activities. It consumes no time and uses no resources. When it marks the
completion of one or more activities, it is not "reached" (does not occur)
until all of the activities leading to that event have been completed.

predecessor event: an event that immediately precedes some other event
without any other events intervening. An event can have multiple
predecessor events and can be the predecessor of multiple events.

successor event: an event that immediately follows some other event
without any other intervening events. An event can have multiple successor
events and can be the successor of multiple events.
Que.6 what are the operation of concrete technology ?
Ans.6 there are 2 operation of concrete technology following given below: a. formwork - Complete system of temporary structure built to contain fresh
concrete so as to form it to the required shape and dimensions and to
support it until it hardens sufficiently to become self-supporting. Formwork
includes the surface in contact with the concrete and all necessary
supporting structure.
b. Centering - It is a temporary supporting structure to a soffit. It is the
specialized formwork used in the construction of arches, shells space
structure where the entire false-work is (struck or decentred) as a unit to
avoid introducing injurious stress in any part of structure
formwork
 requirement for ideal formwork : material used for formwork :- timber , ply wood, hard board, steel etc.
 removal of formwork:1. wall,column,& vertical side of beams – 24 to 48 hrs
2. slabs (props left under)- 3 days
3. beams soffits (props left under)-7 day
4. removal of props to slabs – spanning upto 4.5m :- 7days
spanning over 4.5m :-44 days
5. removal of props to beams and arches- spanning upto 6 m :- 7 days
spanning over 6m :- 21 days
concreting ‘‘centering’’
1.storing – a. storing of cement , aggeregates ,& water
2.batching- a.batching of cement, aggeregates,& water
3.mixing-
a.hand mixing & machine mixing
4.handling and transporting
5.placing and compacting
6.finishing
7.curing
8.formwork removal
Que.7 Discuss the PERT & its 3 estimates ?
Ans .7 Discuss the pert & its three estimates
Before any activity begins related to the work of a project, every project
requires an advanced, accurate time estimate. Without an accurate estimate,
no project can be completed within the budget and the target completion
date.
Developing an estimate is a complex task. If the project is large and has many
stakeholders, things can be more complex.
Therefore, there have been many initiatives to come up with different
techniques for estimation phase of the project in order to make the estimation
more accurate.
The PERT (Probabilistic) Approach
So far we have talked about projects, where there is high certainty about the
outcomes of activities. In other words, the cause-effect logic is well known.
This is particularly the case in Engineering projects.
However, in Research & Development projects, or in Social Projects which are
defined as "Process Projects", where learning is an important outcome, the
cause-effect relationship is not so well established.
In such situations, the PERT approach is useful, because it can accommodate
the variation in event completion times, based on an expert’s or an expert
committee’s estimates.
For each activity, three time estimates are taken

The Most Optimistic

The Most Likely

The Most Pessimistic
The Duration of an activity is calculated using the following formula:
Where te is the Expected time, to is the Optimistic time, tm is
the most probable activity time and tp is the Pessimistic time.
It is not necessary to go into the theory behind the formula. It is enough to
know that the weights are based on an approximation of the Beta distribution.
The Standard Deviation, which is a good measure of the variability of each
activity is calculated by the rather simplified formula:
The Variance is the Square of the Standard Deviation.
Or
PERT (Program Evaluation and Review Technique) is one of the successful and
proven methods among the many other techniques, such as, CPM, Function
Point Counting, Top-Down Estimating, WAVE, etc.
PERT was initially created by the US Navy in the late 1950s. The pilot project
was for developing Ballistic Missiles and there have been thousands of
contractors involved.
After PERT methodology was employed for this project, it actually ended two
years ahead of its initial schedule.
The PERT Basics
At the core, PERT is all about management probabilities. Therefore, PERT
involves in many simple statistical methods as well.
Sometimes, people categorize and put PERT and CPM together. Although CPM
(Critical Path Method) shares some characteristics with PERT, PERT has a
different focus.
Same as most of other estimation techniques, PERT also breaks down the tasks
into detailed activities.
Then, a Gantt chart will be prepared illustrating the interdependencies among
the activities. Then, a network of activities and their interdependencies are
drawn in an illustrative manner.
In this map, a node represents each event. The activities are represented as
arrows and they are drawn from one event to another, based on the
sequence.
Next, the Earliest Time (TE) and the Latest Time (TL) are figured for each
activity and identify the slack time for each activity.
When it comes to deriving the estimates, the PERT model takes a statistical
route to do that. We will cover more on this in the next two sections.
Following is an example PERT chart:
The Three Chances
There are three estimation times involved in PERT;
 Optimistic Time Estimate (TOPT),
 Most Likely Time Estimate (TLIKELY), and
 Pessimistic Time Estimate (TPESS).
In PERT, these three estimate times are derived for each activity. This way, a
range of time is given for each activity with the most probable value, TLIKELY.
Following are further details on each estimate:
1. TOPT
This is the fastest time an activity can be completed. For this, the assumption
is made that all the necessary resources are available and all predecessor
activities are completed as planned.
2. TLIKELY
Most of the times, project managers are asked only to submit one estimate. In
that case, this is the estimate that goes to the upper management.
3. TPESS
This is the maximum time required to complete an activity. In this case, it is
assumed that many things go wrong related to the activity. A lot of rework and
resource unavailability are assumed when this estimation is derived.
The PERT Mathematics
BETA probability distribution is what works behind PERT. The expected
completion time (E) is calculated as below:
E = (TOPT + 4 x TLIEKLY + TPESS) / 6
At the same time, the possible variance (V) of the estimate is calculated as
below:
V = (TPESS - TOPT)^2 / 6^2
Now, following is the process we follow with the two values:

For every activity in the critical path, E and V are calculated.

Then, the total of all Es are taken. This is the overall expected completion
time for the project.

Now, the corresponding V is added to each activity of the critical path. This
is the variance for the entire project. This is done only for the activities in
the critical path as only the critical path activities can accelerate or delay
the project duration.

Then, standard deviation of the project is calculated. This equals to the
square root of the variance (V).

Now, the normal probability distribution is used for calculating the project
completion time with the desired probability.
Conclusion
The best thing about PERT is its ability to integrate the uncertainty in project
times estimations into its methodology.
It also makes use of many assumption that can accelerate or delay the project
progress. Using PERT, project managers can have an idea of the possible time
variation for the deliveries and offer delivery dates to the client in a safer
manner
Que.8 Discuss the difference b/w CPM & PERT ?
Ans 8 PERT vs CPM
CPM and PERT (Program Evaluation and Review Technique) are most
commonly used methods for project management. There are some
similarities and differences between PERT and CPM. PERT can be applied to
any field requiring planned, controlled and integrated work efforts to
accomplish defined objectives.
On the other hand, CPM (Critical Path Method) is the method of project
planning consisting of a number of well defined and clearly recognizable
activities.
PERT/CPM – Differences between PERT and CPM
Though PERT and CPM both are used for project management, there are
differences between CPM and PERT. The relative table for PERT vs CPM is
shown below.
CPM
PERT

CPM uses activity oriented network.

PERT uses event oriented Network.

Durations of activity may be estimated
with a fair degree of accuracy.

Estimate of time for activities are not
so accurate and definite.

It is used extensively in construction
projects.

It is used mostly in research and
development projects, particularly
projects of non-repetitive nature.

Deterministic concept is used.

Probabilistic model concept is used.

CPM can control both time and cost
when planning.

PERT is basically a tool for planning.

In CPM, cost optimization is given
prime importance. The time for the
completion of the project depends
upon cost optimization. The cost is not
directly proportioned to time. Thus,
cost is the controlling factor.

In PERT, it is assumed that cost varies
directly with time. Attention is
therefore given to minimize the time
so that minimum cost results. Thus in
PERT, time is the controlling factor.
Relationship :- Pert is the general case where the activity time is descrived
by three time estimates , measuring the uncertanity by standard daviation
and variance,
Where as the CPM is the particular case when all the time
estimate coincide with one value and the standard daviation and variance
disapear
Que.9 what is planning, scheduling and controlling ?
Ans .9 Planning, Scheduling (or organising) and Control are considered to
be basic Managerial functions, and CPM/PERT has been rightfully accorded
due importance in the literature on Operations Research and Quantitative
Analysis.
Far more than the technical benefits, it was found that PERT/CPM provided
a focus around which managers could brain-storm and put their ideas
together. It proved to be a great communication medium by which thinkers
and planners at one level could communicate their ideas, their doubts and
fears to another level. Most important, it became a useful tool for
evaluating the performance of individuals and teams.
There are many variations of CPM/PERT which have been useful in planning
costs, scheduling manpower and machine time.
Project Planning
In the process of planning , alternatives are examined and the best
alternative is chosen. The goal of planning is to minimize resource use
(cost) while satisfactorily completing the task . Efficient use of equipments ,
material , labor and ensuring coordinated effort are the basic aim . The
outcome of planning is predetermined course of action.Thus, the planning
creates an orderly sequence of events, defines strategies to be followed in
carrying forth the plan and describes ultimate disposition of the result.
Putting the various activity of the project in the sequence on the time
frame is the process of scheduling . Scheduling is required for continuous
checking of the project (control), for resource mobilization , to minimize the
cost and use of resources optimally.
Various scheduling techniques have been employed to plan the activity in
sequence in project management . In construction project , bar chart and
critical path method (CPM) have been widely used . During the planning
process , a manager builds the facilities on paper , thus identities each of
the various tasks and time .During construction , these predetermined
course of action form the basis for monitoring and the checking the
progress of the work . Following steps are followed during planning ,
scheduling and control .
Que. 10 what is scheduling , uses , advantages, classification & method ?
Ans .10
Defination
construction scheduling is a graphical representation which shows the
phasing rate of construction activities with the starting and completion
dates and the squential relationship among the various activities or
operation in a project is that work can be carried out in an orderly and
effective manner
Uses
1. It gives the qquantity of works.
2. the actual progress of the work.
3.the project can be carried out in a symmetric manner using
Scheduling .
Advantages
1. By studying the scheduling of any kind of work and the many alternative
method of execution, we can choose the best one.
2. it gives the clear idea regarding the reqquired men, material, and
equipment at different stage of the work.
3. resourses utilization is optimized.
4. actual progress of the work is monitored with the actual plan.
5. total duration of the complete project is known.
Classification of scheduling
it is classified into different types of requirement such as :-
1.
2.
3.
4.
Material scheduling
Labour scheduling
Equipment scheduling
Financial scheduling and other types.
Method of scheduling
Scheduling can be done by different methods depending on the size of
the project . the methods used are :
1. Bar chart or Gantt charts
2. Milestones chart
3. Network analysis.
Scheduling of Activities Using a Gantt Chart
Once the activities are laid out along a Gantt Chart (Please see chart
below), the concepts of Earliest Start & Finish, Latest Start & Finish
and Float will become very obvious.
Activities 1-3 and 2-4 have total float of 1 week each, represented by
the solid timeline which begins at the latest start and ends at the
latest finish. The difference is the float, which gives us the flexibility to
schedule the activity.
For example, we might send the staff on leave during that one week
or give them some other work to do. Or we may choose to start the
activity slightly later than planned, knowing that we have a week’s
float in hand. We might even break the activity in the middle (if this is
permitted) for a week and divert the staff for some other work, or
declare a National or Festival holiday as required under the National
and Festival Holidays Act.
These are some of the examples of the use of float to schedule an
activity. Once all the activities that can be scheduled are scheduled to
the convenience of the project, normally reflecting resource
optimisation measures, we can say that the project has been
scheduled.
Que.11 what is Sequencing Activities ?
Ans .11
Sequencing Activities
Sequencing is the process of identifying and documenting relationship among the
project activities. Activities are
ordered based on their logical relationships and all but the first and the last are
linked to at least one predecessor
and one successor.
Sequencing Basics
Sequencing can be affected by
•
Product Description, characteristics or layout
•
Necessary Dependencies
•
Discretionary Dependencies
•
External dependencies
Sequencing Techniques
There are several commonly discussed networks including PERT/CPM and PDM.
The Precedence Diagramming
Method (PDM) is the one most frequently used for illustrating the dependent
relationships among project activities
and, consequently, the follow of work from start to end of the project.
Characteristics of the PDM are:
•
Activities are shown as geometric shapes.
•
Arrows between activities identify only relationships – they do not
represent work.
•
An arrow from one activity to another means that the successor activity
cannot start until the predecessor
activity is complete.
•
If the activity has more than one predecessor, it cannot start until all
predecessors are complete.
Project Activity Characteristics
•
Work is performed and described in terms of a verb, adjective, and noun –
there is action performed.
•
A single person or organization is responsible for the work – more than one
resource may be assigned to
an activity, but one person is in charge of delivering the output. If this is not the
case, the items need further
decomposition or joint responsibilities clarified.
•
It has a defined starting point – there is a specific action that can be
identified that marks the start of an activity
or a predecessor activity that must be completed.
•
There is a tangible output or product at completion (usually) – projects
occasionally have level-of-effort
activities or support activities without clearly defined outputs; however, the
primary activities have defined and
measurable outputs. The point at which an activity is completed is determined by
the availability of an output
product that is used as input by a successor activity.
•
It fits logically under an existing WBS element – if it does not, then either
the activity is not part of the project,
the WBS needs modification, or the activity is ambiguous and needs redefinition.
•
It is of a size and duration that is sufficient for control – activities that are
too long do not provide sufficient
time for corrective action if problems arise, and too many activities that are too
short can make the cost of
the control more expensive than a problem that may arise; however, using a
rolling wave concept where the nearterm activities are relatively short and those
many months in the future are larger
Que.12 calculation of time estimates in cpm ?
Ans .12 Calculation of Time Estimates in CPM
In the project network given in figure below, activities and their durations are
specified at the activities. Find the critical path and the project duration.
Calculations in Network Analysis
The following calculations are required in network analysis in order to prepare a
schedule of the project.
a. Total completion time of the project
b. Earliest time when each activity can start (i.e. earlist start time)
c. Earliest time when each activity can finish (i.e. earlist finished time)
d. Latest time when each activity can be started without delaying the project
(i.e. latest start time)
e. Latest time when each activity can be finished without delaying the project
(i.e. latest finish time)
f. Float on each activity (i.e. time by which the completion of an activity can
be delayed without delaying the project)
g. Critical activity and critical path
The symbols used in the calculations are shown in table below.
Symbol
Description
Ei
Earliest occurance time of event i
Lj
Latest allowable occurance time of event j
tEi-j
Estimated completion time of activity (i,j)
(EST)ij
Earliest starting time of activity (i,j)
(EFT)ij
Earliest finishing time of activity (i,j)
(LST)ij
Latest starting time of activity (i,j)
(LFT)ij
Latest finishing time of activity (i,j)
The computations are made in following steps.
(a) Forward Pass Computations :
(b) Backward Pass Computations :
(c) Calculation of Slack:
Event slack is defined as the difference between the latest event and earlist event
times.
Slack for head event = Lj - Ej
Slack for tail event = Li - Ei
The calculations for the above taken example network are summarised below in
the table.
S(i)
Predecessor Successor
tEi-j
Event i
Event j
(EST)ij
5
10
7
0
7
0
7
0
5
15
12
0
12
7
19
-
5
20
17
0
17
5
22
-
(EFT)ij
(LST)ij
(LFT)ij
Slack
10
20
15
7
22
7
22
0
10
25
9
7
16
21
30
-
15
30
11
12
23
19
30
7
20
25
5
22
27
25
30
-
20
30
8
22
30
22
30
0
25
35
10
27
37
30
40
3
25
45
15
27
42
35
50
-
30
35
10
30
40
30
40
0
30
40
8
30
38
35
43
-
35
45
10
40
50
40
50
0
40
45
7
38
45
43
50
5
(d) Determination of Critical Path:
The sequance of critical activities in a network is called the critical path. The
activities with zero slack of head event and zero slack for tail event, are called as
crititcal activities. In the taken network, the following activities are critical
activities: 5 - 10, 10 - 20, 20 - 30, 30 - 35, 35 - 45.
Thus the critical path is A - E - G - K - M.
Critical path duration is 7 + 15 + 8 + 10 + 10 = 50.
Calculation of Expected Time and Variance of a Path in PERT
The Expected Time of a chain of activities in series, is the sum of their expected
times. Similarly the variance of the path, is the sum of variances of activities on
the path. In Figure below, three activities A,B and C are connected in series, (i.e.
form a path). Their time estimates to-tm-tpare given along the activity arrows.
The expected time of the path 1-2-3-4 is calculated as:
As the length of the path ,that is the number of activies connected in series
increases,the variance of the path and hence the uncertainty of meeting the
expected time also increases.
An Example
In the network of figure below, the PERT time estimates of the activities are
written along the activity arrows in the order to-tm-tp. Compute the expected
time and variance for each activity. Also compute the expected duration and
standard deviation for the following paths of the network.
(a) 10-20-50-80-90
(b) 10-30-50-70-90
(c) 10-40-60-80-90
The computation of expected times and variances for different activities are
carried in a table given below.
Activity
i
Time Estimates
j
to
tm
Expected Time Variance
tp
tE
σ2
10
20
6
9
12
9.00
1.00
10
30
3
5
9
5.33
1.00
10
40
10
14
18
14.00
1.78
20
50
7
10
13
10.00
1.00
20
70
3
4
8
4.5
0.69
30
50
4
10
12
9.33
1.78
40
50
8
11
14
11.00
1.00
40
60
5
10
15
10.00
2.78
50
70
3
4
5
4.00
0.11
50
80
11
15
14.67
1.00
60
80
7
9
12
9.17
0.69
70
90
4
8
10
7.67
1.00
80
90
6
7
9
7.17
0.25
17
Que .13 define the pert calculation ?
Ans .13. PERT Calculations for the Social Project
In our Social Project, the Project Manager is now not so certain that
each activity will be completed on the basis of the single estimate he
gave. There are many assumptions involved in each estimate, and
these assumptions are illustrated in the three-time estimate he would
prefer to give to each activity.
In Activity 1-3, the time estimates are 3,12 and 21. Using our PERT
formula, we get:
The Standard Deviation (s.d.) for this
activity is also calculated using
the PERT formula
We calculate the PERT event times and other details as below for each
activity:
Event
to
tm
tp
te
ES
EF
LS
LF
TF
s.d.
Var.
1-3
3
12
21
12
0
12
0
12
0
3
9
3-5
6
15
30
16
12
28
12
28
0
4
16
1-2
2
5
14
6
0
6
5
11
5
2
4
2-4
5
14
17
13
6
19
11
24
5
2
4
3-4
2
5
8
5
12
17
19
24
7
1
1
4-5
1
4
7
4
19
23
24
28
5
1
1
Que .14 what is job lay out or site layout ?
Ans .14
. Construction site or job layout involves identifying, sizing, and placing
temporary facilities (TFs) within the boundaries of construction site. These
temporary facilities range from simple laydown areas to warehouses, fabrication
shops, maintenance shops, batch plant, and residence
facilities. Required temporary facilities and their areas are depending in many
factors including project type, scale, design, location, and organization of
construction work.
Site planning in particular, has been the most neglected aspect in the
construction industry and the attitude of the engineers has been that it will be
done as the project progress. It is important to realize that the site planning will
be the conditions that site personnel will live with for the total duration of the
construction period. Thus the careful pre-planning is imperative.
Site Layout Planning Elements
A well planned site including all temporary facilities and utilities lead to:
increasing productivity and safety, 2) reducing area(s) needed for temporary
construction, and 3) maximizing utilization. The following points should be
considered in good site layout.
1. Safety
2. Site Accessibility
3. Information Signs
4. Security
5. Accommodation
6. Offices
7. Water Supply and Sanitation
8. Material Handling
9. Storage and site cleaning
10.Craft Change-Houses
11.Batch plant and Fabrication Shops
Temporary Facilities Characteristics
It is important to understand the characteristics of the temporary facilities before
planning the site layout. Six generic temporary facility characteristics are
discussed in this section.
1. Satisfying environmental and safety regulations: All temporary facilities should
satisfy environmental and safety regulations.
2. Availability of diverse solutions for the same problem: There are many
arrangements that can be made to establish a temporary facility. For example, if a
warehouse is required, the planner can build a warehouse on the site, use existing
facilities on the site, rent a building near the site, or plan a just in time delivery.
3. Relatively short life span of a specific location: The life span of temporary
facility depends on the duration of the project. In general, it must be removed as
soon as the project is completed.
4. Reutilization with a minimum loss for the same or modified function at another
location: Due to the shorter life span of temporary facility on site, planners
consider reutilization of the temporary facilities. This can result in saving the cost
of construction.
5. Easy of assembly, dismantling, and exploitation: temporary facilities structures
which are easy to assemble and dismantle will reduce both assembly and
disassembly time.
6. Standardization of design: Standardization of design and construction of
temporary facilities can increase the frequency of reutilization and reduce the
work-hours and cost required for construction the facilities
8. Examples of Site Layout Planning
Example 1
Figure 2 illustrates the layout of building materials and access roads for the
purposes of servicing
two hoists for the erection of a low-rise building. Comment on and criticize the
present layout in
relation to the positioning of both the materials and hoists.
Que. 1Explain clearly the difference between an activity and an event.
Ans. 1
Activity - Activity stands for the time consuming part of a project. It represents a
job.Activities are denoted by arrows.
Event - The event (also called node) is either the beginning or end of a job. Events
aredenoted by circles. Event does not consume time.When all activities and events
in a project are connected logically and sequentially, they forma network.
Que.2 In what ways does a CPM network differ from Pert network ?
Ans .2
 PERT (Programme Evaluation & Review Technique) is event oriented
whereas CPM(Critical Path Method) is activity oriented.
 In CPM based network analysis no allowance is made for the uncertainties
in theduration of time involved.
 In CPM, times are related to costs.
Que.3. Define, (i) predecessor event (ii) successor event
Ans .3 Event or events that immediately come before another event are called
predecessor events tothat event. Event or events that immediately follow
another event are called successor eventsto that event.
Que .4Draw a PERT network of opening a new office. Assume that following
events take place insome sequence.
Event 1: Location of site started
Event 2: Location of site completed
Event 3: Building for office selected
Event 4: Cleaning of the office building started
Event 5: Interior decorator starts work
Event 6: Interior decorator finishes work
Event 7: Opening of new office advertised or announced
Event 8: List of invitees for the opening day prepared
Event 9: Invitations sent
Event 10: Office opened
Ans .4 see fig.