Example

Team-Fly    

Integrated Project Management
By Earl Hall, Juliane Johnson
Table of Contents
Chapter 7.  Critical Path


The following example illustrates a project in which several strings of tasks ending with slack parallel the critical paths. When using only the Gantt chart critical path, this relationship is hard to track and to utilize for managing a project's execution.

A National Marketing and Sales Project

A company that manufactures machinery for light metal fabrication has developed a new piece of machinery and has planned a marketing/sales campaign to push the sale of this product. The major tasks are sales, marketing, advertising, and printing. The detail tasks and the scheduled duration of each task and interdependencies are shown in Table 7-2 and Figure 7-6.[1] (Note: There are some interdependencies of sub-tasks among the four major work packages.)

[1] William K. Holstein and Walter H. Warrek, Arrow Diagram Exercise. Boston: Harvard Business School. 1995. Copyright 1965 by the President and Fellows at Harvard College. Reprinted by permission.


Figure 7-6.

graphics/07fig06.gif


This is an unusual case. There are two critical paths through the project. Also, several sequences of tasks parallel the critical paths, and they have an accumulation of slack at the end of their sequence. This accumulated slack can be used to adjust resources for any task in the sequence, not just the last task. This feature makes the arrow diagram critical path chart particularly useful.

Note the sequence tasks L, M, and N end with slack. This means the start date of L, or all the start dates for L, M, and N can be delayed successively if the delay does not use up all available slack between N and U. Even if all the slack was used up, there is more slack after Task U to protect the timeline.

Table 7-2.

Sales Task

Days

Dependency

A. Prepare Phase 1 of training

(8)

None

B. Sales managers select trainees

(2)

None

C. Sales personnel relieved of duty and sent to home office

(4)

B

D. Train sales personnel in Phase 1

(10)

A & C

E. Prepare Phase 2 of sales training (Approval of Phase 2 training after general marketing approach is completed as required)

(9)

A

F. Conduct Phase 2 sales of training

(12)

D & E & I

G. Sales trainees become familiar with customer instruction manual

(5)

BB & F

H. Sales trainees return to territory

(1)

G

Marketing Task

Days

Dependency

I. Determine general marketing approach

(10)

None

J. Select marketing personnel

(4)

I

K. Bring marketing personnel to home office

(2)

J

L. Consolidate training plans for marketing personnel

(2)

I

M. Design a familiarization course for marketing personnel

(8)

L

N. Train marketing personnel

(8)

M & K

Advertising

Days

Dependency

O. Firm up advertising plans

(6)

I

P. Prepare a paper

(6)

O

Q. Get paper printed in a professional journal

(8)

P

R. Prepare national advertising approval

(4)

O

S. Get national advertising approved

(4)

R

T. Distribute advertising to media

(2)

S

U. Release national advertising

(2)

N & Q & T

Printing

Days

Dependency

V. Draft and approve a general brochure

(4)

O

W. Layout of brochure

(5)

V

X. Print a brochure

(3)

W

Y. Prepare a customer instructional manual

(3)

V

Z. Approve a customer instructional manual

(1)

Y

AA. Print an instructional manual

(2)

Z

BB. Send a customer manual to sales training center

(1)

AA

CC. Package brochure and manual and deliver them to marketing for general distribution

(8)

X & AA

Implement Campaign

   

If L M N runs out past the designated start time for Task U, there is still slack time between the end of Task U and the end of the project identified by the completion of Tasks H and CC.

The project manager may note that many tasks in the project can overrun or start late without affecting the project's completion date. Slack that is identifiable at the end of Task Q can be used to enable Task P to start a half-day late. Slack identifiable at the end of Tasks AA and BB will protect the project if Task Y overruns by one day.

The diagram in Figure 7-6 reveals many ways the project can be adjusted without affecting its end date. These characteristics are not as obvious on a computer-created Gantt chart. The computer software generates a Pert chart that has arrow diagram characteristics and is somewhat more helpful for these purposes than the Gantt chart, but it is not as useful as the arrow diagram. It is this type of clear and complete arrow diagram (showing that the A D F G H sequence and the I O V W X CC sequence are both critical) that the project manager provides for each team member prior to the risk analysis discussion meeting.

Figure 7-6 shows the "National Marketing and Sales" project arrow diagram laid out with each of the critical paths on a parallel straight line. The slack represented between Task I and F is not useful slack. As a predecessor to Task F, Task I is completed long before Task D and has plenty of slack. However, Task I is on the second critical path as a predecessor to Task O and has no slack there. The slack between Tasks BB and G is likewise not useful slack. The slack between Tasks BB and CC is useful for the Y Z AA BB sequence. Because of Tasks BB's relationship to the second critical path, the slack between Tasks BB and G is not usable.


    Team-Fly    
    Top


    Integrated Project Management
    Integrated Project Management
    ISBN: 0071466266
    EAN: 2147483647
    Year: 2005
    Pages: 190

    Similar book on Amazon

    flylib.com © 2008-2017.
    If you may any questions please contact us: flylib@qtcs.net