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Box 14, Folder 3, Document 9
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MSA
CRITICAL PATH ISSUE NO, 6
A BULLETIN DEVOTED TO ADVANCED TECHNIQUES OF MANAGEMENT
PUBLISHED AND DISTRIBUTED BY MANAGEMENT SCIENCE ATLANTA, INC.
VOL. IIINO. 2 NOVEMBER 1964
HOME OF THE BRAVES SCHEDULED BY CPM
At this writing the long task of obtaining a
definite commitment from a major league baseball club
to occupy the large $18-million Atlanta Sports Stadium
next spring is almost completed. Construction of the
stadium is almost one-half completed, and the Critical
Path Method is helping to.assure that the job will be
completed in time to toss out the first ball to the new
Atlanta (nee Milwaukee) Braves next April.
The extremely short schedulé, 12 months, desired
by the Atlanta and Fulton County Recreation Authority
resulted in premium bid prices for the construction
contract and the need for close control of the schedule.
The architects, a joint venture of Heery and Heery and
Finch, Alexander, Barnes, Rothschild and Paschal,
required the use of CPM for progress reports by the
contractor. It turned out that the low bidder on the 12-
month schedule was a firm with recent experience in
using CPM on stadium construction. The contractor,
Thompson & Street Company, had used CPM to help
finish the University of Georgia Coliseum 40 days
ahead of schedule (Pathfinder, August 1963).
As in the Coliseum project, Management Science
Atlanta assisted Thompson and Street in setting up the
CPM schedule for the stadium and in handling much cf
the periodic updating. The network for the stadium
contains 3240 activities drawn on 16 pages. The
computer selected for the CPM processing was the
Burroughs B-5000 at the Rich Electronic Computer
Center at Georgia Tech. The B-5000 program has a
capacity of 524,288 activities.
The specifications called for updating the CPM
schedule every two weeks. At these updating periods,
the progress of the previous two weeks, along with
any changes in the logic of the construction plan
which have developed during the reporting period, are
fed to the computer and a current status report and new
schedule are generated.
The management of Thompson & Street has stated
that they would have used CPM on this project even if
it had not been required. They report that one of the
major uses of the updated schedules is better co-ordi-
nation among the many subcontractors, the general
contractor, the architect, and the owner. A computer
printout of the CPM schedule was made a part of many
of the subcontracts. The CPM plan and schedule has
also helped signal the need for some major revisions of
the original construction plans.
An example of the type of management action which
is implemented by the CPM schedule was the change in
the established location of the precast yard. The
original location of the yard was in the playing field
area which would be close to the points of use for the
cast structural items. A computer report indicated that
there would not be enough time remaining after the
finish of the precasting operation to be able to erect
the temporary football bleachers, obtain the owner's
approval, and remove the stands to clear the field for
baseball. Consequently, the precast yard was con-
structed in the parking lot.rather than on the playing
field.
Figure 1. Atlanta's Major League Sports Stadium Will Seat 50,000 for Baseball, 57,000 for Football.
a
= wm
“——
= ci gine.
© Management Science Atlanta, Inc. 1964
NETWORK FORMATS DIFFER
Currently, there are three project networking
formats in use: (1) activity-on-arrow, (2) event
oriented, and (3) activity-on-node. Interestingly,
the apparent best format, the activity-on-node, is
least used.
In the activity-on-node format, activities are
graphically represented by nodes instead of arrows.
The arrows are used to represent only the dependency
relationships among the nodes. This format does not
require the use of special dummy activities. The
principal advantage of the format is its simplicity,
since the avoidance of dummy activities eliminates
the majority of networking problems. Professor
John Fondahl of Stanford University, a noted CPM
authority, supports the activity-on-node format as
the best. The format is not too widely used primarily
because it was not noticed until after the other
formats became popular, and very few CPM computer
programs are written for it.
In the activity-on-arrow format, activities are
graphically represented by arrows. The arrows are
interconnected to show, as nearly as practical, the
true dependency relationships among activities. To
correctly show dependencies, the activity-on-arrow
format requires the frequent use of dummy activities
at merge and burst points.
In the event-oriented format, which is most
closely associated with PERT, the nodes may repre-
sent either "start" or "end" events. Activity
descriptions are placed inside the nodes, and
activities are represented by arrows, upon which
time estimates are noted. Among users of the system,
there is considerable variation in the use of start
events and dummies. The system is essentially a
hybrid combination of the other two systems. Due to
its ambiquity at merge points and non-standard con-
ventions, the event-oriented system often causes
problems of misinterpretation.
Examples of each of the three formats are
illustrated below, along with common errors made when
the two most popular formats are used.
Management Science Atlanta currently uses the
activity-on-arrow format almost exclusively because
of the wide variety of CPM computer programs written
for it. The popularity of the activity-on-node format,
however, is expected to increase significantly in the
near future. Recently, two new activity-on-node
computer programs were made available, one for the
2. Activity-on-Arrow (Wrong)
3. Activity-on-Arrow (Correct)
DEPENDENCIES FOR SAMPLE NETWORKS
Activity Depends On Activitiy Depends On
A none E A
B A E D, H
Cc A G D,E,H
D B, C H CG
4, Event Oriented (Wrong)
O-O-®) |
®
1. Activity-on-Node (Correct)
5. Event Oriented (Correct)
MSA
CRITICAL PATH ISSUE NO, 6
A BULLETIN DEVOTED TO ADVANCED TECHNIQUES OF MANAGEMENT
PUBLISHED AND DISTRIBUTED BY MANAGEMENT SCIENCE ATLANTA, INC.
VOL. IIINO. 2 NOVEMBER 1964
HOME OF THE BRAVES SCHEDULED BY CPM
At this writing the long task of obtaining a
definite commitment from a major league baseball club
to occupy the large $18-million Atlanta Sports Stadium
next spring is almost completed. Construction of the
stadium is almost one-half completed, and the Critical
Path Method is helping to.assure that the job will be
completed in time to toss out the first ball to the new
Atlanta (nee Milwaukee) Braves next April.
The extremely short schedulé, 12 months, desired
by the Atlanta and Fulton County Recreation Authority
resulted in premium bid prices for the construction
contract and the need for close control of the schedule.
The architects, a joint venture of Heery and Heery and
Finch, Alexander, Barnes, Rothschild and Paschal,
required the use of CPM for progress reports by the
contractor. It turned out that the low bidder on the 12-
month schedule was a firm with recent experience in
using CPM on stadium construction. The contractor,
Thompson & Street Company, had used CPM to help
finish the University of Georgia Coliseum 40 days
ahead of schedule (Pathfinder, August 1963).
As in the Coliseum project, Management Science
Atlanta assisted Thompson and Street in setting up the
CPM schedule for the stadium and in handling much cf
the periodic updating. The network for the stadium
contains 3240 activities drawn on 16 pages. The
computer selected for the CPM processing was the
Burroughs B-5000 at the Rich Electronic Computer
Center at Georgia Tech. The B-5000 program has a
capacity of 524,288 activities.
The specifications called for updating the CPM
schedule every two weeks. At these updating periods,
the progress of the previous two weeks, along with
any changes in the logic of the construction plan
which have developed during the reporting period, are
fed to the computer and a current status report and new
schedule are generated.
The management of Thompson & Street has stated
that they would have used CPM on this project even if
it had not been required. They report that one of the
major uses of the updated schedules is better co-ordi-
nation among the many subcontractors, the general
contractor, the architect, and the owner. A computer
printout of the CPM schedule was made a part of many
of the subcontracts. The CPM plan and schedule has
also helped signal the need for some major revisions of
the original construction plans.
An example of the type of management action which
is implemented by the CPM schedule was the change in
the established location of the precast yard. The
original location of the yard was in the playing field
area which would be close to the points of use for the
cast structural items. A computer report indicated that
there would not be enough time remaining after the
finish of the precasting operation to be able to erect
the temporary football bleachers, obtain the owner's
approval, and remove the stands to clear the field for
baseball. Consequently, the precast yard was con-
structed in the parking lot.rather than on the playing
field.
Figure 1. Atlanta's Major League Sports Stadium Will Seat 50,000 for Baseball, 57,000 for Football.
a
= wm
“——
= ci gine.
© Management Science Atlanta, Inc. 1964
NETWORK FORMATS DIFFER
Currently, there are three project networking
formats in use: (1) activity-on-arrow, (2) event
oriented, and (3) activity-on-node. Interestingly,
the apparent best format, the activity-on-node, is
least used.
In the activity-on-node format, activities are
graphically represented by nodes instead of arrows.
The arrows are used to represent only the dependency
relationships among the nodes. This format does not
require the use of special dummy activities. The
principal advantage of the format is its simplicity,
since the avoidance of dummy activities eliminates
the majority of networking problems. Professor
John Fondahl of Stanford University, a noted CPM
authority, supports the activity-on-node format as
the best. The format is not too widely used primarily
because it was not noticed until after the other
formats became popular, and very few CPM computer
programs are written for it.
In the activity-on-arrow format, activities are
graphically represented by arrows. The arrows are
interconnected to show, as nearly as practical, the
true dependency relationships among activities. To
correctly show dependencies, the activity-on-arrow
format requires the frequent use of dummy activities
at merge and burst points.
In the event-oriented format, which is most
closely associated with PERT, the nodes may repre-
sent either "start" or "end" events. Activity
descriptions are placed inside the nodes, and
activities are represented by arrows, upon which
time estimates are noted. Among users of the system,
there is considerable variation in the use of start
events and dummies. The system is essentially a
hybrid combination of the other two systems. Due to
its ambiquity at merge points and non-standard con-
ventions, the event-oriented system often causes
problems of misinterpretation.
Examples of each of the three formats are
illustrated below, along with common errors made when
the two most popular formats are used.
Management Science Atlanta currently uses the
activity-on-arrow format almost exclusively because
of the wide variety of CPM computer programs written
for it. The popularity of the activity-on-node format,
however, is expected to increase significantly in the
near future. Recently, two new activity-on-node
computer programs were made available, one for the
2. Activity-on-Arrow (Wrong)
3. Activity-on-Arrow (Correct)
DEPENDENCIES FOR SAMPLE NETWORKS
Activity Depends On Activitiy Depends On
A none E A
B A E D, H
Cc A G D,E,H
D B, C H CG
4, Event Oriented (Wrong)
O-O-®) |
®
1. Activity-on-Node (Correct)
5. Event Oriented (Correct)
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