1. Day 19
ELC 347/BUS 348/PSA 347

2. Agenda Questions? IP Part 4 IP Part 5 Assignment 6 Corrected
Missing .mmp file with costs update
IP Part 5
Due Nov 18
Developing a Project Schedule
Assignment 6 Corrected
3 A’s and 1 B
Assignment 7 Posted
Only one more
Exam 2 Corrected
2 A’s, 1 B and 1 C
Finish Critical Chain Project Scheduling

3. Finals Rescheduling Do IP Project presentation on Dec 12
Exam 3 done asynchronously via Blackboard on Dec 16
Final IP Project Due Dec 18

4. Project Scheduling: Lagging, Crashing, and Activity Networks
Chapter 10
Project Scheduling: Lagging, Crashing, and Activity Networks

5. Boeing 787 1st Delivery September 25, 2011

6. Chapter 10 Learning Objectives
After completing this chapter, students will be able to:
Apply lag relationships to project activities.
Construct and comprehend Gantt charts.
Recognize alternative means to accelerate projects, including their benefits and drawbacks.
Understand the trade-offs required in the decision to crash project activities.
Develop activity networks using Activity-on-Arrow techniques.
Understand the differences in AON and AOA and recognize the advantages and disadvantages of each technique.

7. Lags in Precedence Relationships
The logical relationship between the start and finish of one activity and the start and finish of another activity.
Four logical relationships between tasks
Finish to Start
Finish to Finish
Start to Start
Start to Finish

8. Finish to Start Lag Most common type of sequencing
Shown on the line joining the modes
Added during forward pass
Subtracted during backward pass
This lag is not the same as activity slack A
Spec Design 6 B
Design Check 5 C
Blueprinting 7
Lag 4

9. Finish to Finish Lag Two activities share a similar completion point
The mechanical inspection cannot happen until wiring, plumbing, and HVAC installation are complete A
Plumbing 6 B
HVAC 5 C
Inspection 1 D
Wiring
Lag 3

10. Start to Start Lag
Logic must be maintained by both forward and backward pass A
Plumbing 6 B
HVAC 5 C
Inspection 1 D
Wiring
Lag 3

11. Start to Finish Lag Least common type of lag relationship
Successor’s finish dependent on predecessor’s start D
Wiring 6
Lag 3 A
Plumbing 6 B
HVAC 5 C
Inspection 1

12. Gantt Charts Establish a time-phased network
Can be used as a tracking tool
Benefits of Gantt charts
Easy to create and comprehend
Identify the schedule baseline network
Allow for updating and control
Identify resource needs

13. Create a Gantt chart based on the activities listed in the table. Task
Time
Pred Z 8 -- U 3 W Y 5 T 6 V X S 7
U,T 4
Y,X R 9
Task ES EF LS LF Z Y X W V U T S R
gantt.mpp

14. Completed Gantt Chart for Project Delta
FIGURE 10.8  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

15. Gantt Chart for Project Delta with Critical Path Highlighted
FIGURE 10.9  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

16. Gantt Chart with Resources Specified
FIGURE 10.10  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

17. Gantt Chart with Lag Relationships
FIGURE 10.11  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

18. Gantt Chart with Lag Relationships

19. Principal methods for crashing
The process of accelerating a project
Principal methods for crashing
Improving existing resources’ productivity
Changing work methods
Compromise quality and/or reduce project scope
Institute fast-tracking
Work overtime
Increasing the quantity of resources

20. Managerial Considerations
Determine activity fixed and variable costs
The crash point is the fully expedited activity
Optimize time-cost tradeoffs
Shorten activities on the critical path
Cease crashing when
the target completion time is reached
the crashing cost exceeds the penalty cost

21. Formula Slope = crash cost – normal cost normal time – crash time
CRASHING ACTIVITIES – AN EXAMPLE
Formula Slope = crash cost – normal cost
normal time – crash time
Example – Calculating the Cost of Crashing
SUPPOSE:
NORMAL ACTIVITY DURATION = 8 WEEKS
NORMAL COST = $14,000
CRASHED ACTIVITY DURATION = 5 WEEKS
CRASHED COST = $23,000
THE ACTIVITY COST SLOPE =
23,000 – 14, or, $9, = $3,000 per week
8 –

22. Project Activities and Costs
Table 10.1
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

23. FIGURE 10.14 Time–Cost Trade-Offs for Crashing Activities
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

24. Project costs Pre Normal Crashed Crash/day Days Gained activity
Duration
Cost A 5
1000 3
1500
250 2 B 7
700 6
300 1 C
2500
4000 D - E
C,D 9
3750
9000
1750 F 4
1600
900 G
2400
3000 H
E,F,G
15000
2000
Total
22450
37500

25. Normal Netw0rk 7 4 3 5 9 9 5 6 Project time = 28 days
Project Cost = $22450

26. Fully Crashed Netw0rk
Project time = 19 days
Project Cost = $37,500

27. Partially Crashed Netw0rk7 4 3 6
Project time = 19 days
Project Cost = $34,200 (save $3,300)

28. FIGURE 10.16  Relationship Between Cost and Days Saved in a Crashed Project
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

29. Other costs Previous examples only includes direct costs What about
Indirect costs (overhead)
$ per day overhead
Late penalties
$ per day late

31. What is the lowest cost to complete this project in 53 weeks
What is the lowest cost to complete this project in 53 weeks? Times are in weeks and costs in dollars.
Activity
Pred
Normal Time
Min Time
Normal Cost
Crash Cost A -- 14 9
500
1500 B 5 2
1000
1600 C 10 8
2000
2900 D
B, C
2500 E 6
1900 F
3000 G
E, F 7 4
600
1800 H 15 11
3600
Initial early and late start and finish times
Task ES EF LS LF Slack A B C D E F G H
Project 63
Reduce A by 5 days at $200/week = $1000 Project length is now 58 weeks
Reduce G by 3 days at $400/week = $1200 Project length is now 55 weeks
Reduce C by 2 days at $450/week = $900 Project length is now 53 weeks
Total cost to finish project in 53 weeks is $3100 more than normal cost of $9800
crash.mpp, crash.xls

32. Activity on Arrow Networks
Activities represented by arrows
Widely used in construction
Event nodes easy to flag
Forward and backward pass logic similar to AON
Two activities may not begin and end at common nodes
Dummy activities may be required

33. Notation for Activity-on-Arrow (AOA) Networks
FIGURE 10.18
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

34. Project delta Activity Pre Duration A 5 B C 6 D B,C 13 E F 4 G 9 H2

35. Sample Network Diagram Using AOA Approach
FIGURE 10.19  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

36. Representing Activities with Two or More Immediate Successors(Wrong)
FIGURE 10.20A  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

37. Alternative Way to Represent Activities with Two or More Immediate Successors (Wrong)
FIGURE 10.20B  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

38. Representing Activities with Two or More Immediate Successors Using Dummy Activities (Better)
FIGURE 10.20C  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

39. Partial Project Delta Network Using AOA Notation
FIGURE 10.21  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

40. Completed Project Delta AOA Network
FIGURE 10.22  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

41. Project Delta Forward Pass Using AOA Network
FIGURE 10.23
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

42. Project Delta Backward Pass Using AOA Network
FIGURE 10.24  
Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

43. Calculate early and late start and finish times for all activities.
Use AOA to sketch the network that represents the project as described in the table.
Calculate early and late start and finish times for all activities.
Activity
Time
Pred A 3 -- F 4 D B 5 G 2 C 7 H
E,F,G
B,C E
Task ES EF LS LF A B C D E F G H K

45. Controversies in the Use of Networks
Networks can be too complex
Poor network construction creates problems
Networks may be used inappropriately
When employing subcontractors
The master network must be available to them
All sub-networks must use common methods
Positive bias exists in PERT networks

46. Summary Apply lag relationships to project activities.
Construct and comprehend Gantt charts.
Recognize alternative means to accelerate projects, including their benefits and drawbacks.
Understand the trade-offs required in the decision to crash project activities.
Develop activity networks using Activity-on-Arrow techniques.
Understand the differences in AON and AOA and recognize the advantages and disadvantages of each technique.

47. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall