Resource analysis 1

Project management(seminar)

Introduction• Sometimes one or more resources (especially

skilled workers) are equally or more important than time. According to priority, there are:– time-limited and – resource-limited

projects. Priority can change over time but it is not wise to have double priorities.

• Basic tools came from production engineering: loading (resource allocation)

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.

Defining resources for projects• SOW• WBS• Task list

– Resource needs given in resource-hours (e.g. man-hour, machine-hour)

– Two forms of resource specification:• Rate-constant (can be changed to a constant

function/patter): constant usage rate defines the duration, too

• Total constant: to finish the activity

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

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

Capacity

• Be realistic:– Usual efficiency– Estimated absenteeism, sickness, holidays– Existing commitments– Ancillary tasks and their resource needs– Any additional constraints (like methodology) and

limitations (like work contracts)

• Also calculate with the possibilities (cost, time, trade-offs) to increase capacity

Defining resources for projects 2• SOW• WBS• Task list• Logical connections (PNT)• Gantt chart and histogram• Levelling

Using the bar chart

• Set up and analyse the network– Assign the resource data to the activities

• Draw the Gantt chart– Aggregate each resource time period by time

period throughout the total project

• Cumulating (Summation or S Curve):• Use levelling the load for optimization

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 1Res. aggr. 5 5 9 9 9 5 5 3 3 3 1 1 1Cum. res. 5 10 19 28 37 42 47 50 53 56 57 58 59

Resource units11 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 1Res. aggr. 1 1 3 3 3 9 9 9 9 9 1 1 1Cum. res. 1 2 5 8 11 20 29 38 47 56 57 58 59

Resource units11 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

Scheduling with constraints

Three approaches:• Allocation: Activities are scheduled so that an

initially defined limit of resources or time is not exceeded.

• Levelling: A previously generated schedule must be given. Then it levels out the peaks and troughs without changing the TPT.

• Smoothing: A start time, a TPT and resource priorities.

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

21

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

21

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

654

3

21

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 1Res. aggr. 5 5 7 7 7 5 5 5 5 5 1 1 1Cum. res. 5 10 17 24 31 36 41 46 51 56 57 58 59

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

Reading

• Lockyer – Gordon (2005): Chapter 17

Thanks for your attention