Resource Management Types of Constraints q Time q

Resource Management

Types of Constraints q Time q Resource q Mixed Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -2

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 period e. g. work – Storable: depleted only by usage (remains available if not used) e. g. money • The most common resource typology, the 4 Ms: – – – 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.

Resource Loading The amounts of individual resources that a schedule requires during specific time periods. Resource loading table Resource Name Tom Assign Bids Jeff Work 40 hrs Details 5/5 5/12 5/19 5/26 Work 8 h 32 h Calculate Cost Sue Select Bid Carol PR Campaign 40 hrs 8 hrs Work Work Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 8 h 8 h 8 h 32 h 32 h 8 h 8 h 12 -5

What to do with non-linear durationresource functions? • Use a computer • Focus on quasi-linear parts of the functions

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 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -7

Prioritization Rules for Leveling v Smallest amount of slack v Smallest duration v Lowest ID number v Greatest number of successor v Requiring the most tasks resources Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -8

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 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -9

Creating Resource Loading Charts (1/4) Display the amount of resources required as a function of time. 4 B 5 Res = 2 0 A 4 Res = 6 5 D 9 Res = 7 9 E 11 Res = 3 1. Start with a network diagram 4 C 7 Res = 2 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 11 F 12 Res = 6 12 -10

Creating Resource Loading Charts 2/4 Activity Resource Duration A 6 4 B 2 1 C 2 3 D E F 7 3 6 4 2 1 ES 0 4 4 Slack 0 0 4 LF 4 5 11 5 9 11 0 0 0 9 11 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 -11

Creating Resource Loading Charts 3/4 3. Draw an initial loading chart with each activity scheduled at its ES. Resources 8 6 4 A D B 2 C 2 4 F Resource imbalance E 6 8 10 12 Project Days Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 14 12 -12

Creating Resource Loading Charts 4/4 4. Rearrange activities within their slack to create a more level profile. Splitting C creates a more level project. Resources 8 6 4 A B 2 C 2 4 D C F E 6 8 10 12 Project Days Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 14 12 -13

Key Parameters in Multi-Project Environments Ø Schedule slippage Ø Resource utilization Ø In-process inventory Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -14

Prioritizing Resource Allocations in Multi-Project Environments • First come first served • Greatest resource demand • Greatest resource utilization • Minimum late finish time • Mathematical programming Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -15

Problem solving

Network with single resource data 0 2 0 0 0 0 2 a (1) 2 2 0 0 5 5 5 b (4) 5 10 c (3) 8 10 3 5 0 10 0 2 START (0) 0 2 0 5 3 7 d (2) 5 10 10 10 0 13 e (1) 3 13 0 13 FINISH (0) 13 0 13

Aggregation with a bar chart (single resource, earliest start) activity 1 2 3 4 5 a 1 1 b 4 4 6 7 8 9 10 4 4 4 c 3 3 3 3 d 2 2 2 e 11 12 13 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 59 1 2 3 4 5 6 7 8 9 10 11 12 13 Resource units 11 10 9 8 7 6 5 4 3 2 1 Time

Aggregation with a bar chart (single resource, latest start) activity 1 2 a 1 1 3 4 5 b c 3 3 3 d 6 7 8 9 10 4 4 4 3 3 3 2 2 2 e 11 12 13 1 1 1 Res. aggr. 1 1 3 3 3 9 9 9 1 1 1 Cum. res. 1 2 5 8 11 20 29 38 47 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 Resource units 11 10 9 8 7 6 5 4 3 2 1 Time

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

S Curve of the example

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 Time • Trying to keep the original TPT unchanged means that critical activities should not be moved. Thus try to move activities with free float. 13

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 Time 8 9 10 11 12 13

Solution activity 1 2 3 4 5 a 1 1 b 4 4 6 7 8 9 10 4 4 4 c 3 3 3 3 d - - - 2 2 2 e 11 12 13 1 1 1 Res. aggr. 5 5 7 7 7 5 5 5 1 1 1 Cum. res. 5 10 17 24 31 36 41 46 51 56 57 58 59

S Curve

Effect of levelling • New „activity”: waiting for the resource (it is a lag, not a true activity) 0 2 0 0 0 0 2 a (1) 2 2 0 0 5 b (4) 5 5 c (3) 8 10 0 5 START (0) 0 2 0 5 0 10 d (2) 5 10 10 10 0 13 e (1) 3 13 0 13 FINISH (0) 13 • Changes: new precedence relationship, floats, late start and finish times 0 13

Optional homework • Hypothetical project resource analysis and planning (4*5 pts): – – Resource need per activity Loading chart Network diagram Smoothing with resource loading charts Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12 -28