1. OPSM 639, C. Akkan Resource Planning Resources affect the schedule, cost and performance of a project. Resources are –Individual people, departments/teams, machines/tools, material. –There could be many of these, how do we know which ones to plan for? Resource planning covers: –Assigning resources to activities; –Understanding the effects of limited resources on the project schedule. –Seeing the contribution of resource costs to the overall cost.

2. OPSM 639, C. Akkan Resource Planning Almost always there are more project proposals than can be handled by the available resources. Schedules created without taking resource limitations into account are bound to be wrong. There is always a need to determine the impact of starting a new project on the availability of resources.

3. OPSM 639, C. Akkan Resource Planning A useful tool for assigning specific project responsibilities to personnel is the project responsibility matrix

4. OPSM 639, C. Akkan Resource Planning In more complicated projects R.M. can have more detail. –In addition to Responsible and Support, as above, there could be Consult, Notify, Approval. Thus, R.M.s outline, responsibility, authority and communication within the organization.

5. OPSM 639, C. Akkan Cost Planning Types of costs in a project: –Direct costs: labor, materials, equipment, etc. chargeable to a work package. Represent actual cash outflows that are paid as the project progresses. These are costs of resources. The cost of an activity (work package) the sum of the costs of resources it uses. –Project overhead costs Cannot be tied to any specific deliverable but serve the entire project. Examples: project manager, consultants, training, travel.

6. OPSM 639, C. Akkan Scheduling Resources Time estimates for work packages (thus the entire project) is done by the implicit assumption that resources would be available. A B C D AB C D ABCD

7. OPSM 639, C. Akkan Scheduling Resources The scheduling problem of the project can be formulated in two different ways: –Minimize the duration of the project subject to resource constraints that can not be violated. (a resource- constrained project model) –Minimize the resource use subject to an imposed due- date constraint. (a time-constrained project model)

8. OPSM 639, C. Akkan Scheduling Resources Some simplifying assumptions to tackle the resource scheduling problem. –Activities can not be split (no preemption). –Level of resource used by an activity is given and cannot be changed.

9. OPSM 639, C. Akkan Scheduling Resources For a time-constrained project a common scheduling objective is resource leveling. –Reducing peaks and valleys of resource requirement to obtain a more or less even resource use throughout the project. –The general approach Create an early-start schedule Delay some activities to even out the resource use. –Drawback: loss of flexibility due to reduction in slack.

10. OPSM 639, C. Akkan Scheduling Resources Consider the following example where there is only a single resource. Given resource requirement is per period. Project deadline is 12. Legend: Act. (dur’n, res. req) A(2,2) B(6,2) C(4,2) D(2,1) E(2,1) F(4,1) G(2,1)

11. OPSM 639, C. Akkan Scheduling Resources Early-start schedule and resource profile

12. OPSM 639, C. Akkan Scheduling Resources Levelled resource schedule (any other alternative?) –maximum resource requirement down to 4 from 5 (20% decrease) –resource utilization increased to 34/(12*4)=71% from 34/*12*5)=57%

13. OPSM 639, C. Akkan Scheduling Resources For the previous example, let’s assume there are only 3 units of the resource available. –To obtain a schedule for which maximum resource requirement is less than or equal to 3 for all time periods, we will have to accept a delayed project. –Resource-constrained project scheduling problem is a combinatorial problem. Hence, even medium-sized problems have too many feasible solutions. –Algorithms to find optimum schedules exist but are very technical and can solve problems with around 50 activities.

14. OPSM 639, C. Akkan Scheduling Resources –A common approach for solving such complicated problems is to use heuristics (algorithms that generally give good solutions, but not necessarily the optimum). –One heuristic type for resource scheduling is “forward scheduling”. Define: an activity is startable if all its predecessors are complete. Idea: Schedule startable activities as early as possible without resulting in a resource constraint violation. Problem: If there is a set of startable activities which cannot all be started without violating the resource constraint, at least one of them must be delayed. Question: which one(s)?

15. OPSM 639, C. Akkan Scheduling Resources The answer to the above question is the use of priorities. –Some scheduling priorities Minimum slack Shortest duration Lowest activity identification number –If there is a tie in one priority, the next one is used to break the tie.

16. OPSM 639, C. Akkan Scheduling Resources A(2,2) B(6,2) C(4,2) D(2,1) E(2,1) F(4,1) G(2,1) 22 Startable tasks: A

17. OPSM 639, C. Akkan Scheduling Resources A(2,2) B(6,2) C(4,2) D(2,1) E(2,1) F(4,1) G(2,1) Time = end of period 2 Startable tasks: B; C; D Slacks: (10 – 8) = 2; (6 – 6) = 0; (4 – 4) = 0 22

18. OPSM 639, C. Akkan Scheduling Resources A(2,2) B(6,2) C(4,2) D(2,1) E(2,1) F(4,1) G(2,1) Time = Startable tasks: Slacks: 22

19. OPSM 639, C. Akkan Scheduling Resources A(2,2) B(6,2) C(4,2) D(2,1) E(2,1) F(4,1) G(2,1) Time = Startable tasks: Slacks: 22

20. OPSM 639, C. Akkan Critical Chain Approach Eliyahu Goldratt’s approach (the author of The Goal) People have a tendency to overestimate the time required for an activity. They usually report 80 to 90th percentile to increase their chances of on- time completion. Paradox: Then why are so many projects late?

21. OPSM 639, C. Akkan Critical Chain Approach Goldratt’s claims the reasons to be: –Work fills available time. –Organizational disincentives for reporting activities finished early. –Early finished activities may not lead to early start of successors because resources (people etc.) may not be available for an early start. –Excessive multi-tasking delays the completion of individual activities.

22. OPSM 639, C. Akkan Critical Chain Approach Goldratt’s solution –make sure people use the 50th percentile as activity time estimates. –Insert “time buffers” (or safety time) at parts of the schedule where there might be problems. –Three types of time buffers are recommended: Project time buffer: to deal with the delay of the activities on the critical path. Merge time buffer: added where non-critical paths merge the critical path. Resource time buffer: to account for the delay of an activity due to a scarce resource required not being available.

23. OPSM 639, C. Akkan Critical Chain Approach