Advanced Scheduling

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