Project and Construction Management

Lecture #4-P2

Project Scheduling

Department of Civil Engineering, Sharif University of Technology

By: Dr. Amin Alvanchi and Dr. Hamed Kashani

Construction Engineering and Management

Outline

Introduction

Schedule Presentation

Scheduling Method: CPM

2

3

Introduction

4

Introduction

Initiation

Organization and planning

Design

Construction

Operation

Maintenance

Demolition

Construction

Project

Lifecycle

5

Introduction

Project Organization

and Contracting

Project planning

Project control

1. Scope

2. Time

3. Cost

Initiation

Organization and planning

Design

Construction

Operation

Maintenance

Demolition

Construction

Project

Lifecycle

Project Schedule

Project schedule is a listing of a project's activities,

milestones, and deliverables, usually with intended

start and finish dates

Project schedule is of paramount importance for

majority of management functions

6

Schedule Presentation

7

Traditionally Schedules Are Presented on Tables

8

Networks used for Schedule Calculation and Presentation

A network is a logical and chronological graphic representation of

the activities composing a project

At their minimum level, project networks present activity

dependencies

They can also represent additional information such as early and

late start time, early and late finish time, slack, resources, etc.

Networks are used for presentation, calculation and optimization of

the project schedules

Many schedule optimization methods use network concepts

Network scheduling has revolutionized construction project

management

It provides management with a more objective and scientific

methodology to scheduling projects

9

Network Example: Activity on Node (AON)

A1

1 10d

10

10

B12

11 7d

18

17

C11

11 3d

13

13

E14

14 12d

25

25

D19

18 6d

24

23

F25

24 1d

25

24

H26

26 5d

30

30

I31

31 5d

35

35

G26

26 10d

35

35

Finish35

35 0d

Activity Name

Activity Duration

Late Start

Early Start

Early Finish

Late Finish

Dependency

10

Gant charts are used for Schedule Presentation

11

Scheduling Method: CPM

12

Basic Steps Involved in Scheduling

CPM or Critical Path Method is the common method used for a

schedule development

Five steps of CPM analysis that should be completed in

chronological order:

1. Identify activities required for the project based on WBS work

packages

2. Identify the dependency (precedency) relationships among the

activities

3. Estimate the resources required (or available) and time

(duration) that each activity can be completed based on the

estimated resources

4. Calculate schedule dates

5. Identify the critical path (the minimum time to complete the

project)

13

1. Define Activities

Identify all activities (work steps/ procedures), and

corresponding work packages specified in the WBS

Organization’s resources (policies, procedures,

templates, forms, etc.) as well as expert judgment and

historical data can be used to define activities

14

Example 1: Casting a Concrete Slab on Grade

Sequence of activities

Extract volumes, quantities and sizes from drawings

Prepare (e.g., purchase) form modules required

Install reinforcement and embedment

Install forms and edges

Place concrete

Strike off or straight edge

Float (if smoother surface is needed)

Control joints

Trowel concrete (if very smooth surface is needed)

Cure concrete (under damp conditions)

15

Example 2: Prepare foundation form work

Sequence of activities

Extract foundation sizes from drawings

Order form sheets

Hire two form-workers for the job

Size form sheets

Install form sheets in place

16

2.Determine Dependencies

Determine dependencies between the activities

Start determining dependencies (precedence) at the task and sub-task

levels, not work packages

Unless impose constraints, assume that activities can be performed in

parallel

Relationships between activities reflect constraints

Regulatory/Contractual

Physical

Resource/Financial

Safety

Managerial

Environmental

17

Types of Dependency

1. Finish to Start (FS)

Initiation of an activity (successor) depends on the completion of

another activity (predecessor)

This is the most common type of activity dependency

Examples:

Initiation of “Prepare (e.g., purchase) concrete form modules”

depends on “Extract volumes, quantities and sizes from

drawings”

Initiation of “Install forms and edges” depends on “Prepare

(e.g., purchase) concrete form modules”

Predecessor Successor

18

Types of Dependency (cont’d)

2. Finish to Finish (FF)

The completion of an activity (successor) depends upon the

completion of another activity (predecessor)

Typically applied when an activity supports another activity

Examples:

Completion of “supply concrete from batch plant” depends

on the completion of “in-place concrete casting”

Predecessor

Successor

19

Types of Dependency (cont’d)

3. Start to Start (SS)

The initiation of an activity (successor) depends upon the

initiation of another activity (predecessor)

Commonly applied when an activity serves as a control for

another activity

Examples:

Initiation of “in-place concrete casting” depends on the

initiation of “install form sheets in place ”

Predecessor

Successor

20

Types of Dependency (cont’d)

4. Start to Finish (SF)

The completion of an activity (successor) depends upon the

initiation of another activity (predecessor)

Completion of predecessor activity depends upon the initiation

of successor

Examples:

Predecessor

Successor

First finish construction and

implementation of the new pipeline

before beginning to shut down and

breaking down the old pipeline

Implementation of a new accounting

system has to be completed before the

company can begin turning off the old

system

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2.Determine Dependencies-Example

22

3.1.1 3.1.2

3.1.3

3.1.4 3.1.5Start

3.1

3.1. Prepare foundation form work :

3.1.1) Extract foundation sizes from drawings

3.1.2) Order form sheets

3.1.3) Hire two form-workers for the job

3.1.4) Size form sheets

3.1.5) Install form sheets in place

3.Estimating Activities

Durations depend implicitly on many factors

Nature of the work that the activity entails

Amount of work

Technique used for the task

Resources used to perform the work

Number of people assigned

Equipment assigned

Productivity (environment, skill, learning, management skills,

etc.)

Costs from cost estimate

Human resources from OBS/WBS and takeoff

Materials, Equipment from takeoff

May want to estimate durations via several ways

23

3.Estimating Activities: Example

3.1. Prepare foundation form work :

3.1.1) Extract foundation sizes from drawings (1 engineer, 1 day)

3.1.2) Order form sheets (1 purchaser, 2 days)

3.1.3) Hire two form-workers for the job(1 HR-person, 1 day)

3.1.4) Size form sheets (2 form-worker, 2 day)

3.1.5) Install form sheets in place (2 form-worker, 4 days)

24

Calculating the project’s schedule using “forward pass” or

by summing up activity durations in different paths from the

start to the finish and “backward pass” calculations by

summing up activity durations in different paths from the

finish to the finish. Example (Prepare foundation form work

last slide):

4. Schedule dates

25

4.Schedule dates: Example (continued)

3.1.1 3.1.2

3.1.3

3.1.4 3.1.5Start

3.1

Start

0d

3.1.1

1d

3.1.2

2d

3.1.3

1d

3.1.4

2d

3.1.5

4d

26

4.Schedule dates: Example (continued)

Start

00d

3.1.1

0 11d

3.1.2

1 32d

3.1.3

0 11d

3.1.4

2d

3.1.5

4d

Forward pass (Earliest start and finish):

Start

00d

3.1.1

0 11d

3.1.2

1 32d

3.1.3

0 11d

3.1.4

3 52d

3.1.5

5 94d

27

4.Schedule dates: Example

(continued)

Backward pass (Latest start and finish):

Start

00d

3.1.1

0 11d

3.1.2

1 32d

3.1.3

0 11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Start 0

00d

3.1.10

0

1

11d

3.1.21

1

3

32d

3.1.32

0

3

11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Slack= 0 Slack= 0

Slack= 0 Slack= 0

Slack= 2

28

5. Critical Path: Example

(continued)

Backward pass (Latest start and finish):

Start

00d

3.1.1

0 11d

3.1.2

1 32d

3.1.3

0 11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Start 0

00d

3.1.10

0

1

11d

3.1.21

1

3

32d

3.1.32

0

3

11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Slack= 0 Slack= 0

Slack= 0 Slack= 0

Slack= 2

Critical

Path

29

3.1. Prepare foundation form work :

3.1.1) Extract foundation sizes from drawings (1 engineer, 1 day)(start day 1 to

finish day 1)

3.1.2) Order form sheets (1 purchaser, 0.5 day) (start day 2 to finish day 3)

3.1.3) Hire two form-workers for the job(1 HR-person, 1 day) (start day 1 to finish

day 1)

3.1.4) Size form sheets (2 form-worker, 2 day) (start day 4 to finish day 5)

3.1.5) Install form sheets in place (2 form-worker, 4 days) (start day 6 to finish

day 9)

Transfer Schedule to the working days

Start 0

00d

3.1.10

0

1

11d

3.1.21

1

3

32d

3.1.32

0

3

11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Slack= 0 Slack= 0

Slack= 0 Slack= 0

Slack= 2 Day 3 finished Day 4 starts (same manner for other nodes)

30

3.1. Prepare foundation form work :

3.1.1) Extract foundation sizes from drawings (1 engineer, 1 day)(start day 1 to

finish day 1)

3.1.2) Order form sheets (1 purchaser, 0.5 day) (start day 2 to finish day 3)

3.1.3) Hire two form-workers for the job(1 HR-person, 1 day) (start day 3 to finish

day 3)

3.1.4) Size form sheets (2 form-worker, 2 day) (start day 4 to finish day 5)

3.1.5) Install form sheets in place (2 form-worker, 4 days) (start day 6 to finish

day 9)

Transfer Schedule to the working days

Start 0

00d

3.1.10

0

1

11d

3.1.21

1

3

32d

3.1.32

0

3

11d

3.1.43

3

5

52d

3.1.55

5

9

94d

Slack= 0 Slack= 0

Slack= 0 Slack= 0

Slack= 2 Day 3 finished Day 4 starts (same manner for other nodes)

31

Thanks to the scheduling program such as MSP and Primavera

which do CPM calculation for us

In actual projects, we introduce WBS, dependency and activity

estimates to these computer programs and they do schedule

calculations and give us schedule dates based on the calendare!

Project Scheduling Programs

32

33

Project Scheduling Programs - Example

Home assignment 6 - CPM

Present following activities in AON (20 Marks). Use CPM calculation to

calculate the schedule (40 Marks). Present early start and early finish days

for each activity on the table from start of the month (10 Marks) Present the

schedule on an MS Project Software. (30 Marks)!

(Due: One week)

Activity Duration Predecessor (FS)

A 8 days -

B 5 days -

C 2 days A

D 6 days A,B

E 30hours D

F 12 hours C, D

34

Thank you!