CONSTRUCTION SCHEDULING &
COST CONTROL
By
PROF. LIAQAT ALI QURESHI
UET TAXILA
Planning & Scheduling
Planning:
Process of choosing the method and
order of work
Scheduling:
Process of determining the interrelationship
of associated timings of operations.
Steps in Construction Scheduling
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Splitting of the project into work activities
Determining logic relationships/interrelationships
between activities.
Construction of Network Diagrams.
Assigning durations to work activities.
CPM Calculations resulting in start times, finish
times and float calculations of activities.
Marking of critical Path
Construction of Bar Charts / Time phased
diagrams.
Activity
 An element of work performed during the
course of a project. Or
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
Network Diagrams
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Any schematic display of the logical relationship
of project activities.
Always drawn from left to right to reflect project
chronology.
Usually a combination of arrows and nodes.
Mainly of two types:
1. Arrow Diagram
2. Node Diagram / Precedence Diagram
Arrow Diagrams
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Activities shown by Arrows. Relationship
between activities shown by nodes / events.
Length of arrows does not obey any scale.
Start-to-finish relationships.
Dummies.
Numbering of nodes / events.
Milestones
Use of Dummy Activity
Activity Durations
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Activity duration is forecasted by any of the several means, including:
(1) Check Past Records.
(2) Check Standards and / or cost guides, if available.
(3) Ask the workers, who will do it
(4) make an educated guess
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Any time units may be allotted to activity durations like days, hours,
weeks, months, shifts, etc.
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In CPM, a single duration is forecasted for an activity.
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In PERT (Program Evaluation & Review Techniques), 3 durations are
forecasted for an activity and mean taken by weighted average method.
Then, Project’s Duration or any Event Completion Time is calculated by
probability distribution.
CPM Calculations
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Calculates the following for each activity
EST = Earliest Starting Time
EFT = Earliest Finishing Time
LST = Latest Starting Time
LFT = Latest Finishing Time
TF = Total Float
FF = Free Float
Total Float is Maximum time for which an activity can be
delayed without delaying the project.
Free Float is maximum time for which an activity cane be
delayed without delaying the start of proceeding activity.
Total Float = Free Float + Interfering Float
Critical Path
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The path (or paths) in the network diagram,
from start to finish, on which all the activities
have zero total and free floats, is called
Critical Path.
It is the longest path (or paths) from start to
finish in a net work diagram.
It gives minimum normal time to complete a
project.
It is usually marked by double lined arrows in
a network diagram.
SINGLE SPAN BRIDGE PROJECT
(ACTIVITY DESCRIPTION)
Activity Code
Operation
Dependence
Est. Dur.
(Days)
ENA
Earthworks, north abutment
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5
ESA
Earthworks, south abutment
ENA
4
CONN
Construction, north abutment
ENA
14
CONS
Construction, south abutment
ESA, CONN
12
COMN
Compaction, north abutment
CONN
2
CIMS
Compaction, south abutment
CONS, COMN
2
RNB
Road, north of bridge
COMN
2
RSB
Road, south of bridge
RNB,COMS
2
-
18
PB
2
PB
Prefabricate bridge deck
TD
Transport deck to site
EB
Erect bridge deck
TD, CONN,
CONS,
COMN
3
LBS
Lay bridge surface
EB, RNB, RSB
2
ICB
Install crash barriers etc.
EB
1
RNB, RSB
1
L
Landscape
Node Diagrams
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Activities shown by Nodes, relationship
between Activities shown by arrows or links.
Easier to construct.
Generally no need of dummies. Instead
dummies used only to give single start or
finish.
CPM Calculations similar to Arrow diagrams.
Bar Chart
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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.
COST MANAGEMENT
COST MANAGEMENT
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Includes processes required to ensure that
the project is completed within the approved
budget.
Processes involved are:
1- Resource Planning
2- Cost Estimating
3- Cost Budgeting
4- Cost Control
1- Resource Planning
Involves determining what physical
resources (people, equipment, materials etc)
and what quantities of each should be used
to perform project activities.
Inputs to Resource Planning
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.
Inputs to Resource Planning
4. Resource Pool Description:
Knowledge of what resources are
potentially available.
5. Organizational Policies:
The policies of the performing organization
regarding staffing and the rental or
purchase of supplies and equipment.
Tools and Techniques to Resource Planning
1.
Expert Judgment
2.
Alternative identifications:
To adopt different approaches for
the same problem.
Outputs from Resource Planning
1.
Resource Requirements:
Description of what types of resources
are required and in what quantities for
each element of the work break down
structure.
Cost Estimating
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Developing an approximation (estimates) of
the costs of the resources needed to
complete project activities.
Includes identifying and considering various
costing alternatives.
Cost Estimating and Pricing
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Cost Estimating involves developing an
assessment of the likely quantitative result-how
much will it cost the performing organization to
provide the product or service involved.
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Pricing is a business decision-how much will
the performing organization charge for the
product or service
Inputs to Cost Estimating
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Work Breakdown Structure
Resource Requirement
Resource Rates:
scheduled or non-scheduled
Activity Duration Estimates
Historical Information
Chart of Accounts:
Describes the coding structure used by the performing
organization to report financial information in its general
ledger
Tools and Techniques for Cost Estimating
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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.
Tools and Techniques for Cost Estimating
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Bottom-up Estimating:
Estimating the cost of individual work
items, then summarizing or rolling up the
individual estimates to get a project title.
(Detailed Estimate)
Computerized Tools:
Use of computerized tools such as
project management software and
spreadsheets to assist with cost
estimating.
Outputs from Cost Estimating
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Cost Estimates
Supporting Details like Scope of work,
Calculation sheet, Assumptions made,
Possible range of results, etc.
Cost Management Plan describing how cost
variances will be managed.
Cost Budgeting
Allocation of overall cost estimates to
individual work items in order to establish a
cost baseline for measuring project
performances.
Inputs to Cost Budgeting
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Cost Estimates
Work Breakdown Structure
Project Schedule
Tools and Techniques for Cost Budgeting
Tools and Techniques for developing project
Cost Estimates are used to develop budgets
for work items as well
Outputs from Cost Budgeting
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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 Scurve.
Cost Control
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
Cost Control
Cost Control includes:
 Monitoring cost performances to detect
variances from plan.
 Ensuring that all appropriate changes are
recorded accurately in the cost baseline
 Preventing incorrect, inappropriate, or
unauthorized changes from being included in the
cost baseline.
 Informing appropriate stakeholders of authorized
changes.
Inputs to Cost Control
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Cost Baseline
Performance Reports
Provide information about cost performance
such as which budgets have been met and
which have not. It also alerts the project team
to issues which may cause problems in the
future.
Inputs to Cost Control
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Change Requests
These may occur in many forms-oral or
written, direct or indirect, externally or
internally initiated, and legally mandated
or optional. These may require increasing
the budget or may allow decreasing it.
Tools and Techniques for Cost Control
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Cost Change Control System
It defines the procedures by which the cost
baseline may be changed. It includes the
paperwork, tracking systems, and approval
levels necessary for authorizing changes.
Performance Measurement
It helps to assess the magnitude of any
variations which do occur.
Tools and Techniques for Cost Control
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Additional Planning
Perspective changes may require new or
revised cost estimates or analysis of
alternate approaches.
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Computerized Tools
Outputs from Cost Control
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Revised Cost Estimates
Budget Updates
Corrective Action
Estimate at Completion
It is a forecast of total project costs based
on project performance.
Lessons Learned
OBJECTS OF COST CONTROL
1 – To have a knowledge of the profit and loss of the
project throughout the duration of the project.
PROJECT PROFITS
1) Client payments.
2) Sale of surplus or scrap material and plant
3) Payments for plants or labor by others, where, this plant or labor is ,
from time to time not required for the project.
PROJECT LOSSES
1) Labor and site office costs
2) Plant costs
3) Site overheads i.e. site facilities, access roads and office etc
4) Cost of tendering including bonds, insurance, etc.
5) Material costs.
6) Head office overheads proportioned over all current projects.
OBJECTS OF COST CONTROL
2 – To have a comparison between the actual
project performance and that conceived in the
original project plan.
Comparison is basically done according to the following
bases:
1) According to units of production
2) According to line items; e.g., labour, material,
equipment, overheads, --3 – Provides feedback data on actual project
performance to future project planning
THANK YOU