RESOURCES SCHEDULING based on Gray & Larson

THE MANAGERIAL PROCESS

Clifford F. Gray Eric W. Larson Third Edition

Chapter 8

Scheduling Resources Copyright © 2006 The McGraw-Hill Companies. All rights reserved.

PowerPoint Presentation by Charlie Cook

SLIDE NAVIGATOR 1. Where we are in Gray’s textbook 2. Problems related to resources 3. Resource constraints as part of project constraints 4. Classification of scheduling problems 5. Resources allocation methods

Copyright © 2006 The McGraw-Hill Companies. All rights reserved.

McGraw-Hill/Irwin 8–2



2. PROBLEMS RELATED TO RESOURCES • Resources are prioritised –Project network times are not a schedule until resources have been assigned. • The implicit assumption is that resources will be available in the required amounts when needed. • Adding new projects requires making realistic judgments of resource availability and project durations.

• Resource are constrained Scheduling – Resource leveling (or smoothing) involves attempting to even out demands on resources by using slack (delaying noncritical activities) to manage resource utilization.



3. Resource constraints as part of project constraints • Technical or Logic Constraints –Constraints related to the networked sequence in which project activities must occur.

• 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. Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


3.1 Examples of constraints

FIGURE 8.1 Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


3.2 Kinds of Resource Constraints • People • Materials • Equipment • Working Capital



4.0 Classification of A Scheduling Problem Classification of Problem –Using a priority matrix will help determine if the project is time or resource constrained.

• CLASS 1 - Time Constrained Project –A project that must be completed by an imposed date. • Time is fixed, resources are flexible: additional resources are required to ensure project meets schedule.

• CLASS 2 - Resource Constrained Project –A project in which the level of resources available cannot be exceeded. • Resources are fixed, time is flexible: inadequate resources will delay the project. Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


RESOURCES ALLOCATION METHODS



5.1: The Assumptions 1. Splitting activities is not allowed—once an activity is start, it is carried to completion. 2. Level of resource used for an activity cannot be changed. 3. Activities with the most slack pose the least risk. 4. Reduction of flexibility does not increase risk. 5. The nature of an activity (easy, complex) doesn’t increase risk.



5.2: Method for Timed Constrained Projects –Projects that must be completed by an imposed date. –Require the use of leveling techniques that focus on balancing or smoothing resource demands by using positive slack (delaying noncritical activities) to manage resource utilization over the duration of the project. • Peak resource demands are reduced. • Resources over the life of the project are reduced. • Fluctuation in resource demand is minimized.



5.2.1: Botanical Garden

Say, we have limitation of resources; only 3 Bh (backhoe) available



5.2.2 Botanical Garden (cont’d)

FIGURE 8.2 (cont’d) Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


5.2.3: Advantages of Demand leveling –Advantages • Peak resource demands are reduced. • Resources over the life of the project are reduced. • Fluctuation in resource demand is minimized.

–Disadvantages • Loss of flexibility that occurs from reducing slack. • Increases in the criticality of all activities.



5.3 Method for Resource constrained projects – Projects that involve resources that are limited in quantity or by their availability. – Scheduling of activities requires the use of heuristics (rules-of-thumb) that focus on the 3 priority rules: 1. Minimum slack 2. Smallest (least) duration 3. Lowest activity identification number

– The parallel method is used to apply heuristics • 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. Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


5.3.1: STEP 1 – look where constrained is

!!!!!!!Resources are constrained here . 5 programmers required at the same time maximum while available = 3

FIGURE 8.3



5.3.1: STEP 2 - Draw resource load chart ES FOR ACTIVITY 2,3&4

TOTAL NO. OF PROGRAMMERS PER PERIOD – OBJECTIVE = TO REDUCE THIS Copyright © 2006 The McGraw-Hill Companies. All rights reserved.

LF FOR ACTIVITY 2,3 &4

FIGURE 8.3 (cont’d) McGraw-Hill/Irwin 8–17

5.3.1: STEP 3 – Identify problematic activity that has minimum slack (PRIORITY RULE 1), period 2-3 Activity with min slack, HENCE load activity 3



5.3.1: STEP 4 – Find next activity with minimum slack = activity 2 However activity 2 requires 2 resources while only 1 left. SO, delay activity 2 by 1 day

Max. Delay start by 1 day AND AREDUCE SLACK FIGURE 8.3 (cont’d) Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


5.3.1: STEP 5 – Find next activity = activity 4. Load activity 4 since it requires only 1 resources However activity 6 requires 1 resources. SO, load activity 4

Max.



5.3.1: STEP 6 – Repeat the process period-by-period; NOW period 3-4 However activity 2 requires 2 resources while only 1 left. SO, delay activity 1 day more

4

0

Max.




5

-1

Max.




6

-2

Max.



5.3.1: STEP 9 – Repeat the process period-by-period; NOW period 6-7 Activity 2,5,6 eligible. Activity 2 with min lack; load activity 2. 1 more programmer available and activity 6 with 0 slack eligible; load activity 6. Next is activity 5 but has to de delayed

6

-2

7

1

2

1

Max.




6

-2

8

0

2

2

1

1

Max.




6

-2

9

-1

2

2

2

1

1

1

Max.




6

-2

10

-2

2

2

2

2

1

1

1

1

Max.



5.3.1: STEP 13 – Repeat the process period-by-period; NOW period 10-11 Activity 2,5,7 eligible. Activity 2 with min lack; load activity 2. 1 more programmer available and activity 5 with -2 slack eligible; load activity 5. Next is activity 7 but has to de delayed

6

-2

10

-2

2

2

2

2

1 1

11

2

1

1

1

-1

Max.



5.3.1: STEP 14 – Repeat the process period-by-period; NOW period 11-12 Activity 2,5,7 eligible. Activity 2 with min lack; load activity 2. 1 more programmer available and activity 5 with -2 slack eligible; load activity 5. Next is activity 7 but has to de delayed

6 12

-2

10 12

-2

2

1 12

2

1

2

1

2

2

2

1

1

1

-2

Max.



5.3.1: STEP 15 – Repeat the process period-by-period; NOW period 12-13 Activity 7 eligible. Activity -2 with min lack; load activity 7.

6 12

-2

10 12

-2

2

1 12

-2

2

1

2

1

2

2

2

1

1

1 1

Max.



5.3.1: STEP 16 – Repeat the process period-by-period; NOW period 13-14 Activity 7 eligible. Activity -2 with min lack; load activity 7.

6 12

-2

10 12

-2

2

1 12 14

-2

2

1

2

1

2

2

2

1

1

1 1

1

Max.



6 12 12 10 12

-2

2

2

2

2

2

1

1

8 -2 1

12 14

2

1

1

1 1

-2

Max. = Not A; typo error

2 5

1

3

7 6

4 8 12

1

5.3.1: STEP 17 – Update network/schedule

Max. = Not A; typo error

2 5

1

3

7 6

4

8 12


Computer Demonstration of ResourceConstrained Scheduling • EMR Project –The development of a handheld electronic medical reference guide to be used by emergency medical technicians and paramedics.

• Problem –There are only eight design engineers who can be assigned to the project due to a shortage of design engineers and commitments to other projects.



EMR Project: Network View of Schedule before Resources Leveled



EMR Project before Resources Added



EMR Project—Time Constrained Resource Usage View, January 15–23, 2005

FIGURE 8.7A Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


Resource Loading Chart for EMR Project, January 15–23, 2005

FIGURE 8.A7B Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


EMR Project Network View Schedule after Resources Leveled



EMR Project Resources Leveled



The Impacts of Resource-Constrained Scheduling • 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. Copyright © 2006 The McGraw-Hill Companies. All rights reserved.


Splitting/Multitasking • Splitting/Multitasking –A scheduling technique use to get a better project schedule and/or increase resource utilization. • Involves interrupting work on an activity to employ the resource on another activity, then returning the resource to finish the interrupted work. • Is feasible when startup and shutdown costs are low. • Is considered the major reason why projects fail to meet schedule.



Splitting/Multitasking



Assigning Project Work • Factors to Consider in Assigning Work: –Don’t always pick the same people for the toughest assignments. –Choose people with an eye to fostering their development through participation on the project. –Pick people with compatible work habits and personalities but who complement each other. –Team-up veterans with new hires to share experience and socialize newcomers into the organization. –Select people who may need to learn work together on later stages of the project or other projects.



Multiproject Resource Schedules • Multiproject Scheduling Problems –Overall project slippage • Delay on one project create delays for other projects

–Inefficient resource application • The peaks and valleys of resource demands create scheduling problems and delays for projects.

–Resource bottlenecks • Shortages of critical resources required for multiple projects cause delays and schedule extensions.



Multiproject Resource Schedules • Managing Multiproject Scheduling –Create project offices or departments to oversee the scheduling of resources across projects. –Use a project priority queuing system: first come, first served for resources. –Centralize project management: treat all projects as a part of a “megaproject.” –Outsource projects to reduce the number of projects handled internally.



Key Terms Heuristic Leveling/smoothing Multitasking Resource-constrained projects Resource profile Splitting Time-constrained projects



RESOURCES SCHEDULING based on Gray & Larson

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