Advanced Scheduling

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29 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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RESOURCES

Roger D. H. Warburton


© Kanabar /

Warburton, 2009

1

Objectives

2


Understand Constraints


Resource Constraints


Leveling

S
CHEDULES

& C
OST

E
STIMATES


Project network times are not a
schedule

until resources have
been assigned


Cost Estimates are not a
budget

until they have been time phased

3

R
ESOURCES

AND

P
RIORITIES


The Project network is not a
schedule

until resources are
assigned


Assumption:


Resources will be available in the
required amounts when needed


Assigning resources requires making
realistic judgments of availability and
project durations

4

R
ESOURCE

C
ONSTRAINT

E
XAMPLE

Plan

Play

Hire

Actors

Select

Theater

Hire

Musicians

Plan

Play

Hire

Actors

Select

Theater

Hire

Musicians

Rehearse

Re
-

hearse

5

T
YPES

OF

P
ROJECT

C
ONSTRAINTS


Technical (Logical) Constraints


Constraints related to the network sequence in which
project activities must occur


Network Diagram


Physical Constraints


Activities that cannot occur in parallel or are affected
by contractual or environmental conditions


Resource Constraints


The absence, shortage, or unique interrelationship
and interaction characteristics of resources that
require a particular sequencing of project activities.

6

C
ONSTRAINT

E
XAMPLE


Resource Dependency takes
precedence over the technological
dependency


Does not violate the technical
dependency

Plan

Play

Hire

Actors

Select

Theater

Hire

Musicians

Re
-

hearse

7

R
ESOURCE

Q
UESTIONS


Will assigned
labor

be adequate?


Will assigned
equipment

be
adequate?


Will outside contractors be needed?


Do unforeseen dependencies exist?


Is there
flexibility

in using
resources?


Is the deadline still realistic?

8

T
YPES

OF

R
ESOURCE

C
ONSTRAINTS


People



designer, engineer, welder, painter


Materials



concrete, survey data, deliveries in winter



night road work


Equipment


Earth moving equipment, copiers


Working Capital

9

C
LASSIFICATION

OF

S
CHEDULING

P
ROBLEMS


Time Constrained


A project that must be completed by
an imposed date


Resource Constrained


A project in which the level of
resources available cannot be
exceeded

10

R
ESOURCE

P
ROBLEMS

Are very complex

even for small networks

11

H
ELP

ON

S
CHEDULING

P
ROBLEMS

The priority matrix helps
determine if the project is
time or resource constrained.

Time

Performance

Cost

Constrain

O

Enhance

O

Accept

O

12

C
RITICAL

R
ESOURCE

Q
UESTION

If the CP is delayed, will resources be
added

to
get the project back on schedule?


“Yes”

Time Constrained


“No”

Resource Constrained

Time

Performance

Cost

Constrain

O

Enhance

O

Accept

O

13

T
IME

C
ONSTRAINED

P
ROJECT


A project that must be
completed by an imposed date.


Project Duration is fixed


Resources are flexible


Resources can be added to
ensure schedule is met

14

R
ESOURCE

C
ONSTRAINED

P
ROJECT


A project in which the level of
resources available cannot be
exceeded


Resources are fixed


Time is flexible


If the resources are inadequate, it is
acceptable to delay the project

15

C
ONSTRAINED

P
ROJECTS


All projects are constrained


Something will have to give


What are the priorities?


Negotiation is key

16

L
IMITING

A
SSUMPTIONS


Splitting activities is not allowed


Once an activity is started, it is carried to
completion


Activities may not be started and stopped


Resources on an activity cannot be changed


Activities with the most slack pose the least
risk


Reduction of flexibility does not increase risk


The nature of an activity (easy, complex)
doesn’t increase risk

17

E
XAMPLE

OF

T
IME

C
ONSTRAINED

B
OTANICAL

G
ARDEN

FIGURE 8.2


One resource: backhoes


Interchangeable

Slack

18

B
OTANICAL

G
ARDEN

(
CONT

D
)

FIGURE 8.2 (cont’d)

19

T
IME

C
ONSTRAINED

P
ROJECT


A project that must be completed by an
imposed date.


Project Duration is fixed


Resources are flexible


Resources can be added to ensure schedule is
met


Smooth the Resources


Focus on Resource Utilization


Erratic resources are difficult to manage


Level the resources


Delay non
-
criticals


Use positive slack to reduce peak demand

20

B
OTANICAL

G
ARDEN

(
CONT

D
)

FIGURE 8.2 (cont’d)

21

B
OTANICAL

P
ROJECT


Activities with slack:


Irrigation, Fence & Walls


Delay Fence & Walls


Smoother


Peak demand reduced


Resources reduced from 4 to 3


Smoother profile, easier to manage


Cost to move (people or machines)


Loss of flexibility


Reduced slack, critical activities


Most slack = least risk

22

E
XAMPLE

OF

T
IME

C
ONSTRAINED

B
OTANICAL

G
ARDEN

FIGURE 8.2


One resource: backhoes


Interchangeable

Slack

23

R
ESOURCE
-
C
ONSTRAINED

P
ROJECTS


Projects that involve resources that are limited in
quantity or by their availability.


Scheduling of activities requires the use of heuristics
(rules
-
of
-
thumb)


A modest network with a few resources has
thousands of feasible solutions

24

R
ESOURCE

A
LLOCATION

M
ETHODS

FOR

R
ESOURCE
-
C
ONSTRAINED

P
ROJECTS


Scheduling of activities requires the use of
heuristics (rules
-
of
-
thumb) that focus on:

1.
Minimum slack

2.
Smallest (least) duration

3.
Lowest activity identification number


The parallel method is the most widely used
heuristic


An iterative process that starts at the first time
period of the project and schedules period
-
by
-
period
any activities scheduled to start using the three
priority rules.

25

S
PLITTING
/M
ULTITASKING


Scheduling technique used to get a better schedule
and/or increase resource utilization


Interrupting work on an activity to employ the
resource on another activity, then returning the
resource to finish the interrupted work.


Feasible when startup and shutdown costs are
low.


Considered a major reason why projects fail to
meet schedule.

26

T
HE

I
MPACTS

OF

R
ESOURCE
-
C
ONSTRAINED

S
CHEDULING


Reduces delay but reduces flexibility.


Increases criticality of events


Increases scheduling complexity


May make traditional critical path no longer
meaningful


Can break sequence of events


May cause parallel activities to become
sequential and critical activities with slack to
become noncritical

27

C
OMPUTER

D
EMONSTRATION

OF

R
ESOURCE
-
C
ONSTRAINED

S
CHEDULING

28

L
EVELING



Within Slack


Outside Slack


Complicated



no simple solution


Destroys the network!


Now what?

29

S
UMMARY
: L
EVELING




How do we Level? After you gather your resource
requirements:


Identify resource peaks


Delay non
-
critical tasks with float


Extend schedule if needed

30

In conclusion:

Resource requirements and
availability impact your schedule. You
must leverage your skills and tools.

W
ORKSHOP


Work on the Resource Requirements Associated
with the Case Study

31

S
CHEDULE

C
OMPRESSION

32

O
BJECTIVE


Understand schedule compression techniques


Understand fast tracking and crashing concepts
within this context.


33

W
HAT

IS

D
URATION

C
OMPRESSION

Duration compression is a special case of
mathematical analysis that looks for ways to
shorten the project schedule without changing the
project scope.






PMBOK® Guide 4
th

Edition


34

W
HY

C
OMPRESSION
?


Schedule does not meet planned milestone dates.


Schedule estimate is longer than what the sponsor
desires.


Applying resource loading and leveling impacts
schedule.


Schedule slip occurs during project execution due to
things like scope creep or other circumstances.


Renegotiated project completion date


35

H
OW
?

Utilize resources, duration,
scope and additional
assets.

Use techniques such as fast
tracking and crashing.


36

F
AST

T
RACKING


Overlap activities.


37

A

B




3d

What are the Risks?

C
RASHING



Apply additional resources to critical path


Often results in greater project costs


Look for least expensive reduction in time


38

D
ISCUSSION


From your experience what additional skills and
assets are available for schedule compression?

39

R
EFERENCES


Kanabar & Warburton: MBA Fundamentals,
Kaplan Publishing, 2008


Gray & Larson: Project Management


The
Managerial Process, McGraw
-
Hill, 2008.


PMBOK: Project Management Institute, 2008

40