Resource analysis

1. Resource analysis Project management (lecture+ seminar)

2. 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)

3. 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

4. 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.

5. 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/pattern): constant usage rate defines the duration, too • Total constant: to finish the activity

6. What to do with non-linear duration-resource functions? • Use a computer • Focus on quasi-linear parts of the functions

7. 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

8. Optimum seeking procedures • Constraints: • Resource-limited projects • Time-limited projects • Resource-limited AND time-limited projects (question of priority) • Methods: • Linear programming • Levelling • Allocation • Smoothing

9. Linear programming Successful only for small networks (up to about 200 activities) Need for precise data

10. Levelling(simplesttechnique) Need for a previously produced starting schedule. Attempts to level out peaks and valleys in resource requirements by rescheduling some activities. Difficulty of interactions between activities.

11. Allocation(for resource limited cases) • Allocation resources • ‘Splitting’ an activity: stopping an activity, which is currently in progress, by the removal of its resources for use on an activity of higher priority. • Two procedures for allocation: • Serial: if only a few activities are splitable • Parallel: if many activities are splitable; more complicated method that needs more time and data

12. Allocation when resources are limited • Serial procedure: • All activities in the project are ranked using constantpriority rule. The most frequently used rule: ascending order of the LSTs with a tiebreaker of the ascending order of total floats(a kind of ‘urgency’). • Activities are scheduled in the above order at the earliest possible point in time consistent with the availability of resources and the precedence requirements. • Step-by-step process: • Draw the network diagram for the logical connections • Compute the activity times and total floats • Plot a Gantt or time-scaled network in tandem with a resource-histogram

13. Allocation when resources are limited • Parallel procedure:Activities are considered sequentially (sub-lists). Unscheduled activities are retained and ranked in the next period with new activities.

14. d a i e l FINISH START b f j g c k h

15. The time-limited case • Balancing the S-curve with milestones: Forcing early activities to start sooner

16. Smoothing (time limited) • Aim is to produce a feasible schedule within the time constraints & provide as smooth a resource requirement profile as possible. • Informational needs of smoothing: • Start time and timeframe (TPT or deadline) • Priority order of the resources required • Prioritising activities and selecting them in order for scheduling (critical activities have supreme priority). • Finding the best place for the activity (placing). • Repeat the process with the next activity.

17. Prioritising activities Considerables: • Resource type(s) and importance • Total work content (resource units per time multiplied with the duration for all resources used on the activity) • Available float Formula if no initial scheduling exists: (Total work content) / (Float remaining) In descending order (greatest first).

18. Placing • The best position is the one that gives the lowest usage increase in the time span of the activity. • Two ways of finding this position: • Visual • Sum of squares: • Calculate the sum of squared resource needs of each period within the questionable time frame (between the ES and LF time of the given activity) for every possible positioning • Choose the position with the lowest value

19. seminar

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

21. 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

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

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

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

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

26. S Curve of the example

27. 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.

28. Other possibilities Alternative resources Alternative methods Alternative sequences (if there is no technical dependency)

29. Levelling the load • Trying to keep the original TPT unchanged means that critical activities should not be moved. Thus try to move activities with free float. We must have a starting allocation of activities over time and a resource constraint (previous example).

30. Solution • Movingactivityd 3 daysinadvance is eliminatingthepeak. There are only 2 activities with free float: b & d Which one to move and to where?

32. S Curve

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

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

35. Network with multiple resource data 0 0 5 3 0 0 0 5 b (4B) f (3A) e (3B) d(2B) FINISH (0) a (2A) c (3A) START (0) 13 10 5 2 2 0 0 0 0 0 3 0 0 5 0 5 0 7 2 8 13 5 10 13 2 3 0 8 3 5 0 5 0 5 0 5 10 13 10 2 0 2 13 13 10 10 10 13 • Resource limits: 5A, 5B

36. Reading • Lockyer – Gordon (2005): Chapter 17& 18

37. Thanks for your attention