Chapter 2.

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Construction Project Planning and Scheduling
Contents:
2.1. Construction Planning
2.2. Steps and stages in Planning
2.3 Planning by client and contractor
2.4 preparing schedule
2.5 Time-Cost Trade-off

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 2.1 Construction Planning
• "If you fail to plan, you are bound to fail"
– Planning is the most important constituent of the
construction management. In the simplest sense
planning is the mental process deciding about the
future line of actions.
• It forms the basis for the project scope, schedule,
resources, quality, risk, and integration
• Planning is done to
– Eliminate or reduce uncertainty
– Improve efficiency of the operations
– Obtain better understanding of the objectives
– Provide basis for monitoring and controlling
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 Objectives of planning
• The main objective of planning of a work is to execute
the project or work most economically in terms of money
and time both.
• The effective planning depends upon the following
factors:
– Proper design of each element of the project
– Proper selection of plant and equipment
– Proper arrangements of repair of plant and equipment at site
– Procurement of required materials well in advance
– Ensure employment of skilled and unskilled employees
– To arrange constant flow of funds in entire project duration
– To provide required level of safety and compensations
– Proper arrangements of communication and mobility in site
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 2.2 Steps and Stages in Planning
Steps involved in planning
– Identifying the likely problems to be encountered in the
execution of the work.
– Ascertaining alternative feasibility of execution of work
– Fixing the time of starting the execution of work
– Deciding the time of delivering the materials at site
– Deciding the quantities and duration of various types of
machines and equipment
– Deciding the number of different types of labors for various
works and duration of their employment
– Estimation of financial need
– Estimation of the duration of completion of the work
– Evaluation of the effectiveness of plan adopted
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 Stages of planning
Usually the stages of planning are as follows:
– Preplanning
• Setting out objectives
• Cost benefit analysis
• Project go / no-go decision
– Detailed planning
• Detailed design and drawings
• Specifications
• Quantities calculation
• WBS is done
• Sequence and scheduling of the activities are done
– Monitoring and controlling
• In this phase, the progress of construction is monitored as per proposed
scheduled.
• Updating of schedule can be carried out according to the actual
progress of work.
• Preparation of the revised forecasts regarding the availability of
various resources is done.

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 2.3 Planning by the Client /Owner/Employer
Pre-tender / pre-construction stage planning
– Clients sets clear objectives of the project
– Client communicate the objectives to all the parties and stakeholders
– After proper investigations of the project, client prepares quantity estimates and
determines the quantum of money required for the completion of the work.
– Take respective approval of the project from concerned authority
– Selection of project team and project appraisal
– Select the consultant (if required)
– Bidding and contract award (Selection of Contractor)
Construction stage planning
– Revision in objectives in responding unexpected events
– Make site available for the contractor
– Timely payment and settlement of claims
– Keep the changes less
– Update performance bond/ security of the contractor
– Timely decision
Post construction stage planning
– Prepares project operation schedule
– Prepares project maintenance schedule
– Project ownership

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 Planning by the Contractor
Pre-tender/ pre-construction stage planning
The planning undertaken by the contractor after receipt of tender notice and
before submitting the bid is known as pre-tender stage planning.
– Careful Study of tender documents and drawings to find out the
quantities of each item of work
– Study of specifications and workout the detailed quality of materials
required for different items
– Determine the availability of construction materials at site or nearby
site.
– Determine the method of work execution i.e. by labor or equipment
– Thorough study of site and site investigations

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 Planning by the Contractor contd..
Construction stage planning
After the acceptance of the tender, the contractor further needs in-depth
planning. This stage of planning is also known as contract planning.
– Studying the alternative methods of construction and to decide about
subcontracting
– Working out detailed quantities of materials required and examine and
fixing the methods of procurement and sources of them
– Working out detailed about construction workforce like skilled and
unskilled manpower
– Working out details of plants, equipment their layout and repair &
maintenance strategy
– Planning for camp facilities, access, accommodations, site offices and
layout
– Planning for surveillance like proper lighting, ventilation, drinking
water, sanitation, first aid treatment
– Study interdependence of different items of works and fixing the
sequence of them
– Finalize the work program of each item of work and to decide the dates
of their starting and completing
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 Planning by the Contractor contd..

Post construction stage planning

• Demobilization of plants and equipment
• Demobilization of labors
• Clearance of materials inventory and its stock
• Handover the project to client in targeted date
• Responsible for the defect liability construction within its period

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 2.4 Preparing Schedule

Scheduling
A construction schedule is a graphic representation which shows the
phasing rate of construction with the starting and completing dates
of each activity and the sequential relationship among various
operations in a construction project.
Use of scheduling
• Following are the use of scheduling
• The quantity of work involved, labor, material, equipment and
money required at each stage of work can be determined by
scheduling.
• The actual progress of the work can be checked from time to time
by scheduling
• The project can be carried out in systematic manner using
scheduling
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Classification of scheduling
Schedules can be classified according to the requirements as
follows:
– Construction schedule
– Materials schedule
– Labor schedule
– Equipment schedule
– Financial schedule
– Control schedule
– Organizational schedule
– Summary schedule

Methods of scheduling
Bar chart or Gantt charts
Milestone charts
Network analysis

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Construction schedule and its preparation
Before preparing construction schedule following information must be
known
– Various operations to be done in a particular project
– Quantum of works to be done in each operation
– Unit of measurement
– Rate of progress of work with due allowance of weather conditions
– Number of labors required
– Number and types of plants and equipment required
– Date of starting and completing the activity
– Correlation between different operations

The procedure of preparing construction schedule is as follows:

– The work or project is divided into number of operations and their inter
dependence or relationship is studied. After the careful study of their
interdependence the sequence of operation is decided
– The quantity of work involved in each operation is to be determined
– The time required for the completion of each operation as well as the
completion of total project is determined. This can be done by knowing
the quantum of work involved and the rate
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 Material Schedule
S.N Descripti Total
ons of Quantity Month
Materials I II III
P A P A P A
1 cement 1500 bags 500 502 700 700 300 302

2 re-bar 100 ton … … 80 20

3 sand 1000 m3

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 Equipment Schedule
S.N Types of Total Total Time
Equipment Number Required Month
Required
I II III IV

P A P A

1 Excavator 1 20 hrs 10 8 1 9
0
2 Mixer 1 60 hrs 15 1 2
0 0
3 Vibrator 1 30 hrs

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 Labor Schedule

S.N. Descriptions Total time

of Labor Required Month
I II III IV
P A P A P A
1 SL 100md 50 20
Mason 50 md
Carpenter 20 md
Bar-bender 30 md
2 USL
3

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 2.5 Time Cost Trade- Off
Project cost
For any project, total expenditure incurred in terms of manpower, equipment,
machinery and materials to complete an activity/ies known as total cost of the
project. The total sum of the project is the sum of two distinct costs. Direct and
Indirect cost
Direct cost
The cost of materials, equipment and manpower spent on implementing an activity
/ ies refers to the direct cost. The direct costs of project are of major concern and
behavior pattern of direct costs with time is of importance. Direct cost of a project
depends on the completion time of project, but the variation is not linear.

Indirect cost
The expenditures which cannot be allotted clearly to the individual activities of
the project but are assessed in total are called indirect costs. The indirect cost
includes overhead charges, administrative and establishment charges, supervision
charges, loss of revenue, loss in profit and penalty etc.

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 Time cost trade-off, why ?
Non-linear time and cost trade-off for an activity Project time-cost relationship:

Total project costs include both direct costs and

indirect costs of performing the activities of the
project.
If each activity of the project is scheduled for
the duration that results in the minimum direct
cost (normal duration) then the time to complete
the entire project might be too long and
substantial penalties associated with the late
project completion might be incurred.
At the other extreme, a manager might choose
to complete the activity in the minimum
possible time, called crash duration, but at a
maximum cost.
Thus, planners perform what is called time cost trade-off analysis to shorten the
project duration.
This can be done by selecting some activities on the critical path to shorten their
duration. As the direct cost for the project equals the sum of the direct costs of its
activities, then the project direct cost will increase by decreasing its duration. On the
other hand, the indirect cost will decrease by decreasing the project duration, as the
indirect cost are almost a linear function with the project duration. © Subash K. Bhattarai 18
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 PCC Work : Providing , laying, compacting and curing 100mm thick plain cement concrete, M15 (1
cement : 2 sand : 4 aggregate) on foundation, floor and other specified area with O.P. cement, sand
15 and stone ballast of 10-20mm size aggregate, proper mixing with mixture machine, laying & placing in
position compacting with vibrator, including curing the job to approved level, lines and dimensions all
complete as per drawings, specifications and instruction of the site engineer.

Quantity Considered for Rate Analysis= 1.000 cu.m.

S.N. Description Quantity Unit Unit Rate Amount

A Labor
A.1 Skilled Labor 0.500 m.d. Rs. 1,000.00 Rs. 500.00
A.2 Unskilled Labor 3.500 m.d. Rs. 735.00 Rs. 2,572.50
Total of Labor Cost Rs. 3,072.50

B Materials
B.1 Cement 320.000 kg. Rs. 16.90 Rs. 5,408.00
B.2 40mm Aggregate 0.520 cu.m. Rs. 3,386.88 Rs. 1,761.17
B.3 20mm Aggregate 0.330 cu.m. Rs. 3,492.72 Rs. 1,152.59
B.4 Sand (Rough Sand) 0.445 cu.m. Rs. 2,928.24 Rs. 1,303.06
B.5 Water Direct Cost 130.000 lit. Rs. 0.26 Rs. 33.80
B.6 Diesel 3.000 lit. Rs. 97.50 Rs. 292.50
B.5 Petrol 0.100 lit. Rs. 111.50 Rs. 11.15
Total of Materials Cost Rs. 9,962.27

C Equipments
C.1 Mixer 0.600 hour Rs. 1,875.00 Rs. 1,125.00
C.2 Vibrator 0.250 hour Rs. 120.00 Rs. 30.00
Total of Equipment Cost Rs. 1,155.00

Total Cost Rs. 14,189.77

Contractor's Overhead (15%) Rs. 2,128.46
Total Including Overhead Indirect Cost Rs. 16,318.23
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 Direct Cost Behavior With Time

Cost
Cost rises if
project is crashed
Direct Cost

Normal
Cost:10000K
Cost rises if project duration
(Project Direct
is prolonged
Cost)

8M Normal Time 12M Tim

10M e
(Project duration)

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 Indirect Cost behavior with time

Indirect Cost
(Directly
Cost proportional)
Cost reduces if
project is crashed

Indirect Cost rises if project duration

Cost is prolonged

Normal Time
Time

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 Total Cost Behavior With Time
Cost

A Total Cost
Cc B
Cn
C
Cm

Direct Cost
Indirect Cost

Tc To Tn Time

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 Definitions of Terms
Normal time
The time usually allowed for an activity by the
estimator is known as normal time. It is the standard
time for that activity and is denoted by (Tn).
Crash time
The minimum possible time in which an activity can
be completed by deploying extra resources is known
as crash time. Beyond the crash time the duration of
an activity cannot be reduced or shortened by any
amount of increase in mobilization. It is denoted by
(Tc). Minimum duration
The duration obtained after
Normal cost
possible crashing of
The direct cost required to complete the activity in activities is known as
the normal duration is called normal cost and is
minimum duration (Tm).
denoted by (Cn).
Further reduction or
Crash cost crashing of duration is not
The direct cost corresponding to the crash time of possible after this point.
completing an activity is known as crash cost and is
denoted by (Cc). 23
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Cost slope
• The direct cost curve generally is a curve as shown below. But
this curve can be approximated by the straight line or more than
one straight lines depending upon the flatness of the curve. Thus
the slope of this straight line is cost slope.
Crash cos t  normal cos t
Cost slope (CS) = Normal time  crash time
Direct Cost

Crash
Point ‘A’
Crash Cost (Cc)

Normal
Point ‘B’
Normal Cost (Cn)

Activity Time
Crash time (Tc) Normal time (Tn)
(Regular time)
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 Time cost trade-off
• Time and cost are the two most important resources that a
project manager deals with. Both resources have
constrained, and the job of a project manager is to have
judicious balance between them. The judicious balance
between time and cost is called Time-Cost trade-off and it
can be achieved by studying the availability and demand
of these resources for the given project.

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From the total cost ACB, the total cost of a project is minimum for certain time
duration. This duration is known as optimum duration (To) for the corresponding
minimum cost (Cm). Further, if the project duration is increased, the total cost will
also increase. On the other hand, if the project duration is decreased to the crash
value, the project cost will be the highest. The optimum duration is less than the
normal duration (Tn) corresponding to the direct costs. This is because both direct
and indirect cost increases beyond the normal duration, whereas below the normal
duration indirect cost decrease, but the direct cost increases.
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 Steps in optimization of cost (Cost optimization through Network)
1. First, draw the network diagram and find out all the possible paths. Critical path and
non-critical paths. Critical path duration is the normal project duration for that
project
2. Calculate the direct cost by adding the normal cost of all activities. Calculate
indirect cost by multiplying project duration with the indirect cost (overhead or
indirect expense) per unit time
3. Calculate the total cost by adding direct cost and indirect cost. This total cost is the
baseline cost for the calculation. Similarly, the longest duration (critical path
duration) is the project duration as a baseline duration for the calculation.
4. Calculate the cost slopes of all activities and rank them in ascending order of cost
slopes.
5. Start crashing the project from a critical path (since this is the project duration) by
selecting such critical activity having least cost slope as per ranking to the
maximum possible extent (observe other non-critical paths which are likely to be
critical)
6. Calculate the direct cost by adding the extra cost of crashing (cost slope X (Tn-Tc))
required for crashing that activity to the direct cost calculated in previous steps and
corresponding indirect cost of reduced project duration.

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 Crashing Contd..
After step six, three possible cases may arise:
Case I: If the same path remains critical (longest) then crashing is considered
for the critical activity serially in the ascending order to their cost slope as far
as possible.
Case II: While crashing the critical path, there may emerge a new critical
path/s then crashing is carried out for the common activity. If there is more
than one common activity, activity with the least cost slope is selected first and
continues serially as per the ranking of cost slopes.
Case III: After crashing as per the case II, if there is a possibility of crashing
then, one activity from each path is selected at one time for crashing. This
crashing is known as simultaneous crashing or parallel crashing. The process is
continued until the project shortening is possible.
Note:
Every time after crashing, the direct cost and indirect cost is calculated to find
out the total cost. If the total cost calculated after crashing is greater than the
earlier step, we come to the end of optimization.
Whereas, for the determination of minimum possible time (Tm), crashing
should be continued until the possibility.

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 Numerical
1. The following table shows the costs and duration of each activity of a
project. The network is shown. The indirect cost may be taken as Rs. 3150.-
per week. Determine the optimum duration of the project and
corresponding minimum cost.
Activity Predecessor Normal duration Normal cost Crash duration Crash cost (Cc)
(Tn) (Cn) (Tc)
A - 7 8000 4 15500
B - 9 5000 6 9500
C A 5 7000 2 10000
D A 6 9000 4 16000
E B,C 6 6000 4 12000

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Solution Drawing the network diagram, finding possible paths, project
duration and total cost: 7, 7

A 2 D
7 6
Possible Duration 0, 0 1 5 C 4 18, 18
Paths (w) B
A–D 13 E
A–C–E
9 6
18 3
B–E 15
12, 12
Here, The path A – C – E is the project duration as it is the critical path.
Therefore, The project duration is 18 Weeks

Direct Cost (Summation of normal

cost of all activities) =  normal
cost = 35000
Indirect Cost (Project duration x
indirect cost per week) = 18 ×
3150 = 56700
 Total project cost (Direct cost +
Indirect Cost) = 91700

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Determining the cost slope of all activities.

Activity Difference in cost Difference in duration Cost slope = (Cc- Rank

Crash cost- normal cost Normal duration - Cn)/(Tn-Tc)
(Cc-Cn) Crash duration (Tn-Tc)

A 15500-8000 =7500 7-4 = 3 7500/3 = 2500 3

B 4500 3 1500 2
C 3000 3 1000 1
D 7000 2 3500 5
E 6000 2 3000 4

Crashing
From Critical path A-C-E, select activity ‘C’ for crashing [activity 'C' has minimum cost slope amongst
critical activities] by 5-2 weeks = 3 weeks (i.e. maximum possible extent) and revised duration be:
(Note be aware of other non-critical path/s as well. We cannot reduce the project duration below other
path’s duration)

Revised duration Revised Cost

Path Duration Extra cost of crashing activity 'C' by 3 weeks = 3 × 1000 = 3000
Increment in Direct cost = 35000 + 3000 = 38000
A– D 13 w
Decrement in Indirect cost = 15 × 3150 = 47250
A– C–E 18 – 3 = 15 w Total Cost of project = 85250
B–E 15 w
As, we see the revised total cost is less than the cost calculated in
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After Crashing activity ‘C’, here we find two critical paths A – C – E and B – E with duration equal to 15
weeks. So, crashing must be carried by selecting common activity from both paths for an immediate
result.
Common Activity Crashing
As we see activity ‘E’ is common to both paths. So selecting activity ‘E’ for crashing by 6 – 4 = 2 weeks
and revised duration be:
Revised duration
Path Duration
A–D 13 w
A–C–E 15 – 2 = 13 w

B–E 15-2 = 13 w

Revised Cost
Extra cost of crashing activity ‘E’ by 2
weeks=
2 × 3000 = 6000
Direct cost = 6000 + 38000 = 44000
Indirect cost = 13 × 3150 = 40950
Total cost = 84950
As, this total cost is lesser than previous step further crashing is possible

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 After Crashing activity E, here we find that all paths become critical at this stage with project duration
equal to 13weeks.
Simultaneous Crashing
Now, Selecting 'A' from path A – D and A – C – E to crash and simultaneously selecting 'B' from path B
– E. Activity 'A' is selected due to common of both paths A – D and A – C – E. So, crashing activities 'A'
and 'B' by 3 weeks simultaneously we get,

Revised duration
Path Duration
A–D 13 – 3 = l0 w
A–C–E 13 – 3 = 10 w
B–E 13 – 3 = 10 w

Revised Cost
Extra cost of crashing activity A
and B by 3 weeks
= 3 × (2500 + 1500) = 12000
Direct cost 12000 + 44000 =
56000 The optimum duration of the project is 13 weeks
Indirect cost = 10 × 3150 = 31500 The minimum cost of the project is Rs. 84950
Total Cost = 87500 The minimum duration of the project is 10 weeks
Here, the total cost is higher than previous step.
Hence, we come to the end of crashing.
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 Try This !

If the indirect cost per week is Rs. 300, find the optimal crashed project completion time
and corresponding minimum cost.

Activity Immediate Time (weeks) Cost (Rs)

predecessor Normal Crash Normal Crash
A – 8 5 2000 2300
B – 10 8 4000 4300
C A 6 5 3000 3125
D A 9 6 5000 5225
E B 10 9 2500 2700
F B 13 13 5000 -
G D. E 5 3 1000 1700

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 References:
1. Subash Kumar Bhattarai et. al. ‘’ A Textbook of Construction
Management" Heritage Publishers and Distributors Pvt. Ltd.,
Bhotahity, Kathmandu.
2. Chitkara, K. K, Construction Project Management, Planning
Scheduling, and Controlling; Second Edition, Tata McGraw Hill
Education Private Limited, New Delhi, India
3. Saleh Mubarak “ Construction Project Scheduling and
Control” Second Edition, Wiley India-Edition
4. Gupta, B.L, Gupta, Amit; Construction Management and
Machinery; Standard Publishers Distributors
5. https://www.researchgate.net/figure/Non-linear-time-and-
cost-trade-off-for-an-activity-Project-time-cost-relationship

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