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 period e.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) e (1) d (2) c (3) b (4) a (1) FINISH (0)
Aggregation with a bar chart (single resource, earliest start) activity a11 b44444 c d22222 e111 Res. aggr Cum. res Resource units Time
Aggregation with a bar chart (single resource, latest start) activity a11 b44444 c d22222 e111 Res. aggr Cum. res Resource units Time
The S Curve analysis The minimum slope level is the less ‘critical’ from the viewpoint of availability
S Curve of the example
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 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 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 Time
activity a11 b44444 c d e111 Res. aggr Cum. res
S Curve
Effect of levelling New „activity”: waiting for the resource (it is a lag, not a true activity) START (0) e (1) d (2) c (3) b (4) a (1) FINISH (0) Changes: new precedence relationship, floats, late start and finish times
Reading Lockyer – Gordon (2005): Chapter 17
Thanks for your attention