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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
21
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!
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