network technology

1.  Network Techniques: Bar Chart, Mile stone chart,
 work break down
 Structure and preparation of networks.
 Network techniques like PERT and CPM.
 In construction Management, Project Monitoring and resource
allocations through network techniques.
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2.  BY MODASSAR ANSARI
 3RD Year
 Department of civil Engineering
 SUBJECT- Construction Technology And Management
 SUBJECT CODE-NCE 603
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3.  Gives Pictorial Representation of Activities.
 Activities begin at EST and show their EFT, FF,
TF, Durations, etc.
 Arrows at the relative ends to show dependency.
 Status Line Concept
 Unable to show complete interdependency
between Activities.
 Time-scaled Network Diagrams show complete
interdependency between Activities.
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4.  A work breakdown structure (WBS), in project
management and systems engineering, is a deliverable-
oriented decomposition of a project into smaller components
 Dividing complex projects to simpler and manageable tasks is
the process identified as Work Breakdown Structure (WBS).
 Usually, the project managers use this method for simplifying
the project execution. In WBS, much larger tasks are broken
down to manageable chunks of work.
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5.  Accurate and readable project organization.
 Accurate assignment of responsibilities to the project team.
 Indicates the project milestones and control points.
 Helps to estimate the cost, time and risk.
 Illustrate the project scope, so the stakeholders can have a
better understanding of the same.
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6.  The preceding sections have dealt
comprehensively with the critical path
 method. As a review, these are the steps to
follow in determining a schedule:
 Complete the CPM network diagram.
 Label each activity with its proper description.
 Check network logic.
 Estimate activity durations.
 Identify each event with a unique node number
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7.  Determine the early event times by implementing the forward
pass computations.
 Determine the late event times by implementing the backward
pass computations.
 Compute total, free, and independent float, and identify the
critical activities on the network.
 Calculate calendar dates for event and activity times.
 If project duration is not suitable, either revise the network or
reschedule
 the start/completions of the event & activities, and once again
go through Steps 5-8.
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8.  If the project duration, starts, and finishes of activities are
suitable,
 arrange the activities in the desired sequence, and tabulate
activity
 identification, description, duration, early and late starts, early
and late finishes, and floats.
 Finally, identify the critical activities.
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9.  Includes processes required to ensure that the
project is completed within the approved budget.
 Processes involved are:
A. Resource Planning
B. Cost Estimating
C. Cost Budgeting
D. Cost Control
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10. Involves determining what physical resources
(people, equipment, materials etc) and what
quantities of each should be used to perform project
activities.
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11. 1. Work Breakdown Structure:
A deliverable-oriented grouping of project elements that
organizes and defines the total scope of the project. It
Identifies the project elements that will need resources.
2. Historical Information
3. Scope Statement:
Contains the project justification and the project
objectives.
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12.  Work Breakdown Structure
 Resource Requirement
 Resource Rates:
scheduled or non-scheduled
 Activity Duration Estimates
 Historical Information
 Chart of Accounts
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13.  Analogous Estimating / Top-down Estimating:
Using the actual cost of a previous, similar project as the
basis for estimating the cost of the current project. It is less
costly but less accurate. (Rough-cost Estimate)
 Parametric Modeling:
Using project characteristics (parameters) in a
mathematical model to predict project costs.
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14.  Cost Baseline
A time-phased budget that will be used to measure and
monitor cost performance on the project. It is
developed by summing estimated costs by period and
is usually displayed in the form of an S-curve.
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15. Cost Control is concerned with
(a) Influencing the factors which create changes to the
cost baseline to ensure that changes are beneficial.
(b) Determining that the cost baseline has changed
(c) Managing the actual changes when and as they occur
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16. An element of work performed during the course
of a project.
An amount of work that can be identified so that
we know what it involves and can recognize,
when it starts and finishes.
An activity normally has an expected duration, an
expected cost, and expected resource
requirements
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17.  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.
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18.  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 .
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19.  Identifying and defining activity
 Defining activity interdependence
 Estimate time and resources for each activity
 Constructing the network,
 Calculations on network for project time earliest start and
finish of activity, resource requirement, etc,
 Project control and project review .
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20.  In the network, it is important to know the criticality of the
activity, time available to perform the activity provided date of
completion of a project. In the previous section we have
already talked about various method of obtaining activity
duration. We shall be interested in the question that
 How early we can start the activity.
 How much we can delay the activity such that target date of
completion of project is not affected
 What the time available to perform the activity.
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21.  Early start time
 Early finish time
 Latest start time
 Latest finish time
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22.  It is the earliest time by which an activity can started.
 Let tij be the activity between events i and j. Let T E
i is the
earliest expected time of the event i then
 Earliest start time is equal is to
EST = T E
i
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23.  The earliest finish time of an activity is the time by which an
activity can be finished earliest. The earliest finish time of an
activity is earliest start time plus activity duration.
EFT = EST + activity duration
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24.  The latest finish time is the time by which an activity must be
finished such that completion of the project is not delayed the
latest finish time of an activity between events i and j is the
latest allowable event time of
LFT= T L
j
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25.  The latest start time is the time by which an activity
must start such that completion of project is not
delayed. The latest start time of an activity between
events i and j is latest finish time minus activity
duration.
LST = LFT – activity duration
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26.  In the last reading we have discuss that in the project with art
interested in time available to execute particular task(activity)
during the project period. We shall introduce the concept float
which tells us how much an activity can fluctuate without
affecting the completion of a project. We shall introduce
following float
 Total float.
 Free float.
 Independent float.
 Interfering float.
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27.  Total float is the maximum time available during which an
activity can fluctuate. It is maximum time available minus
activity duration. The maximum time available in the
difference between latest finish time minus earliest start
time.
Maximum time available to execute the work = LFT – EST
total float = maximum time avalable – activity duration
= LFT – EST - t ij
= LST – EST
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28.  Free float is the time available to fluctuate the activity without
the affecting the succeeding activity. The mean of without
affecting succeeding activity is that the activity must finish
before the earliest occurrence of the head event.
Time available = T E
i – EST
Free float = Time available – activity duration
= T E
i – EST - T E
ij
Free float = T E
i – EFT
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29.  It is the time available to fluctuate if the preceding
activities get completed as late as possible and succeeding
activities get started as early as possible.
Hence time available = Te
i – TL
i
Independent float =Minimum time available – activity
duration
= T E
i – T L
i - T E
ij
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30.  Interfering float is defined as difference
between total float and free float.
I.F=T.F-F.F
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31.  Find critical path
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3
2 7
4
1 86
5
8-10-12
3-7-9 8-10-12
4-6-8
3-5-6
7-10-15
5-8-12

32.  Path A 1-2-7-8
 Path B 1-2-6-8
 Path C 1-3-6-8
 Path D 1-4-5-6-8
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Path Optimistic time Most likely time Pessimistic time
Path A 1-2-7-8 19 26 35
Path B 1-2-6-8 17 26 40
Path C 1-3-6-8 18 27 36
Path D 1-4-5-6-8 19 28 39

33.  Expected time for each activity
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6
4 PLo
E
ttt
t



34. PATH ACTIVITY to tL tP tE ∑tE
A
1-2 6 8 11 8.17
26.342-7 8 10 12 10
7-8 5 8 12 8.17
B
1-2 6 8 11 8.17
26.832-6 4 8 14 8.33
6-8 7 10 15 10.33
C
1-3 3 7 9 6.67
273-6 8 10 12 10
6-8 7 10 15 10.33
D
1-4 5 7 10 7.17
28.33
4-5 4 6 8 6
5-6 3 5 6 4.83
6-8 7 10 15 10.33
Path ‘D’ is critical path
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