Resource Management

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Types of Constraints

Time

Resource

Mixed

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Resources• Definition: anything that is scarce and required for any activity

in the project. Resources are constraints for the project.• Resources can be:

– Non-storable: has to be renewed for each periode.g. work

– Storable: depleted only by usage (remains available if not used)e.g. money

• The most common resource typology, the 4Ms:– Men

– Machines

– Money (cost)

– Material

– Other

Loading (resource allocation)• The assignment of work to an worker, machine or

unit (generally: to a workstation) in time.• A workstation can be:

– underloaded (load < capacity)– fully loaded (load = capacity)– overloaded (load > capacity)

• Fully loading is nearly impossible to reach except in flow production.

• Underloading is the most common, because it respects time. Overloading leads to be late.

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Resource LoadingThe amounts of individual resources that a schedule requires during

specific time periods.

Resource loading table

Resource Name Work Details 5/5 5/12 5/19 5/26

Tom 40 hrs Work 8h 32h

Assign Bids 40 hrs Work 8h 32h

Jeff 40 hrs Work 8h 32h

Calculate Cost 40 hrs Work 8h 32h

Sue 40 hrs Work 8h 32h

Select Bid 40 hrs Work 8h 32h

Carol 8 hrs Work 8h

PR Campaign 8 hrs Work 8h

What to do with non-linear duration-resource functions?

• Use a computer• Focus on quasi-linear parts of the functions

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Resource Leveling (Smoothing)

A multivariate, combinatorial problem

Objectives• To determine the resource requirements so that

they will be available at the right time• To allow each activity to be scheduled with the

smoothest possible transition across resource usage levels

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Prioritization Rules for Leveling

Smallest amount of slack

Smallest duration

Lowest ID number

Greatest number of successor tasks

Requiring the most resources

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General Procedure for Leveling

1. Create a project activity precedence table and network diagram,

2. Develop resource loading tables and a resource profile

3. Determine activity late finish times

4. Identify resource over allocation

5. Level the resource loading table

6. Recalculate net activity slacks and project delay

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Creating Resource Loading Charts (1/4)

Display the amount of resources required as a function of time.

0 A 4 Res = 6

4 B 5 Res = 2

5 D 9 Res = 7

9 E 11 Res = 3

4 C 7 Res = 2

11 F 12 Res = 6

1. Start with a network diagram

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Creating Resource Loading Charts 2/4

Activity Resource Duration ES Slack LF

A 6 4 0 0 4

B 2 1 4 0 5

C 2 3 4 4 11

D 7 4 5 0 9

E 3 2 9 0 11

F 6 1 11 0 12

2. Produce a table that shows the duration, early start, late finish, slack, and resource(s) required for each activity.

Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12-12

Creating Resource Loading Charts 3/4

A

2

4

6

8

2 1210864 14

C

BD

E

F

Project Days

Res

ourc

es

3. Draw an initial loading chart with each activity scheduled at its ES.

Resource imbalance

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Creating Resource Loading Charts 4/44. Rearrange activities within their slack

to create a more level profile. Splitting C creates a more level project.

A

2

4

6

8

2 1210864 14

C

BD

E

F

Project Days

Res

ourc

es

C

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Key Parameters in Multi-Project Environments

Schedule slippage

Resource utilization

In-process inventory

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Prioritizing Resource Allocations in Multi-Project Environments

• First come first served

• Greatest resource demand

• Greatest resource utilization

• Minimum late finish time

• Mathematical programming

Problem solving

Network with single resource data

START (0)

0 00

0 00

0

e (1)

10 130

10 133

0

d (2)

2 73

5 105

3

c (3)

2 100

2 108

0

b (4)

0 55

5 105

5

a (1)

0 20

0 22

0

FINISH (0)

13 130

13 130

0

Aggregation with a bar chart(single resource, earliest start)

activity 1 2 3 4 5 6 7 8 9 10 11 12 13

a 1 1

b 4 4 4 4 4

c 3 3 3 3 3 3 3 3

d 2 2 2 2 2

e 1 1 1

Res. aggr. 5 5 9 9 9 5 5 3 3 3 1 1 1

Cum. res. 5 10 19 28 37 42 47 50 53 56 57 58 59Resource units

11 10

987654321

1 2 3 4 5 6 7 8 9 10 11 12 13

Time

Aggregation with a bar chart(single resource, latest start)

activity 1 2 3 4 5 6 7 8 9 10 11 12 13

a 1 1

b 4 4 4 4 4

c 3 3 3 3 3 3 3 3

d 2 2 2 2 2

e 1 1 1

Res. aggr. 1 1 3 3 3 9 9 9 9 9 1 1 1

Cum. res. 1 2 5 8 11 20 29 38 47 56 57 58 59Resource units

11 10

987654321

1 2 3 4 5 6 7 8 9 10 11 12 13

Time

The S Curve analysis

• The minimum slope level is the less ‘critical’ from the viewpoint of availability

S Curve of the example

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12 13

ES

LS

smoothest

Other possibilities

• Alternative resources• Alternative methods• Alternative sequences

(if there is no technical dependency)

Levelling the load• We must have a starting allocation of activities over time

and a resource constraint (previous example).

Resource units

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8 9 10 11 12 13

Time

• Trying to keep the original TPT unchanged means that critical activities should not be moved. Thus try to move activities with free float.

Resource units

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8 9 10 11 12 13

Time

Solution

• There are only 2 activities with free float: b & d• Which one to move and to where?

• Moving activity d 3 days in advance is eliminating the peak.

Resource units

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8 9 10 11 12 13

Time

activity 1 2 3 4 5 6 7 8 9 10 11 12 13

a 1 1

b 4 4 4 4 4

c 3 3 3 3 3 3 3 3

d - - - 2 2 2 2 2

e 1 1 1

Res. aggr. 5 5 7 7 7 5 5 5 5 5 1 1 1

Cum. res. 5 10 17 24 31 36 41 46 51 56 57 58 59

Solution

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12 13

ES

LS

smoothest

leveled

S Curve

Effect of levelling• New „activity”: waiting for the resource

(it is a lag, not a true activity)

START (0)

0 00

0 00

0

e (1)

10 130

10 133

0

d (2)

5 100

5 105

0

c (3)

2 100

2 108

0

b (4)

0 50

0 55

0

a (1)

0 20

0 22

0

FINISH (0)

13 130

13 130

0

• Changes: new precedence relationship, floats, late start and finish times

Optional homework

• Hypothetical project resource analysis and planning (4*5pts):– Resource need per activity– Loading chart– Network diagram– Smoothing with resource loading charts

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