1. University of Debrecen Mongolian University of Life Sciences
Resource Analysis
Lecturer: Baasansuren Sandui
Department of Management,
School of Economics and Business, MULS

2. Terms and concepts used in resource analysis
Resource – anything that is scare and required for any activity in the project e.g. skilled human resources, equipment, services, supplies, commodities, material, budgets or funds.
Resource loading – the amount of individual resources that a schedule requires during specific time periods e.g. man-hours, machine-hours
Resource levelling (technique) - any form of schedule network analysis in which scheduling decisions are driven by resource constraints
Resource smoothing (technique) - any form of schedule network analysis in which scheduling decisions are driven by time constraint

3. Terms and concepts used in resource analysis
Resource limited schedule – a project schedule whose schedule activity, scheduled start dates and scheduled finish dates reflect expected resource availability. A resource-limited schedule does not have any early or late start or finish dates.

4. Resource profiles Steps necessary to produce a project basic schedule
To create a project activity network diagram
To create a table showing that the activity durations, ES, EF, LS, LF times, and total float available
To create a Gantt Chart that showing a project basic schedule
Based on this basic schedule we can construct a resource profiles

5. Resource profiles Example 1; Constructing a basic schedule
Resource (men) 9 3 6 4 8 7 2 1
Activities
Predecessors
Duration (weeks) A - 4 B 2 C D E 3 F G
F, D H
E, G

6. Project basic schedule - Gantt Chart

7. Resources
As we discussed above resource is anything that is scare and required for any activity in the project. Also resources are constraints for the project.
Resources can be divided in to two main categories:
Non-storable: a resource whose availability has to be renewed for each time period (e.g. labor, machine, special equipment )
Storable (pool resource): a resource that remains available if not used and is only depleted by its usage (e.g. money, raw materials)
The main concern of the storable resources is the total resource consumption over the entire planning horizon. But, for the non- storable resources the concern is with the total resource usage at each point of time.

8. Resources
Based on this different characteristics of resources we can select available methods for resource analysis.
Storable resources are consumable that is why we can analyze this kind of resources using Time-Cost tradeoff method. As you know the objective of this analysis is to minimize the total consumption of storable resources such as money and raw materials over the feasible range of project duration.
Non-storable resources are basically handled through three different mechanisms. Namely /1/ Resource aggregation, /2/ Resource levelling, /3/ Limited resource allocation.

9. Resource aggregation
Resource aggregation is a simplest way of finding the resource requirements for a particular schedule. This is a simple summation of the requirement for each resource throughout the life of the project
The objective of aggregation is to construct the resource usage profiles from the project schedule and the activity resource data.
The result of aggregation procedure would be the manner in which the resource requirements vary for that particular schedule. Of course this would be a valuable input to the project manager for planning both the procurement and the deployment of resources.

10. Earliest start aggregation

11. Latest start aggregation

12. Resource smoothing
To smoothen resource usage profiles by shifting slack activities without worsening total project duration. This is the main objective of the resource smoothing. Resource smoothing also referred as a technique that used to construct time-limited schedule.
As I mentioned above Resource levelling is a form of schedule network analysis in which scheduling decisions are driven by resource constraints. The main objective of the resource levelling is to schedule project activities optimally within a given limited resources. This is also referred as resource limited schedule.
These are the main difference between these two techniques

13. Resource smoothing (time limited schedule)

14. Resource smoothing (time limited schedule)
As I shown you in the example the aim of smoothing is to produce a feasible schedule within the constraints and provide as smooth a resource requirement profile as possible
In order to smoothing we need some information
Start time and timeframe for the project (basic schedule)
Priority order of the resource required
Based on these information we can smooth resources using following techniques:
To minimize the peak level of resource usage (using slack times within the project duration)
To compare sum of squares of the resource usage and select minimum

15. The peak level of resource usage
In this technique our first step is find out peak resource usage from early start schedule
Second step is to set target level of one unit below the peak
Third step is to shift activities to find a schedule that satisfies the target level. If there exits no schedule that satisfies target level and stop the procedure
If yes, continue by setting new target levels and so on…

16. The peak level of resource usage
In our example, peaks and target levels are shown in following graph

17. The sum of squares of the resource usage
The sum of squared resource needs of each period can be calculated between the ES and LF time of a given activity.
This is a step by step procedure that designed to minimize the total sum of squares of the resource usage
That is why it looks at the whole profile, not just the peak(s)
In case of multiple resources the most important resource is considered first, followed by next and so on

18. The sum of squares of the resource usage
Following steps must be done:
List activities in order of precedence (Gantt Chart) – (А-О-А сүлжээ зурах)
Start to schedule last activity using its slack time and schedule it to give the lowest total sum of squares for each time unit. Freeze it at the lowest sum of squares
Do this calculation again to the next activity and till the end of all activities
Select an alternative that has a lowest value of sum of squares and reschedule the project

19. The sum of squares of the resource usage

20. The sum of squares of the resource usage
Gantt Chart
Final result A 9 B 3 C 6 D 4 E 8 F 7 G 2 H 1 5 10 11
Agg. Res
110
Sum of Sq 81
121
100
1104
Gantt Chart
Final result A 9 B 3 C 6 D 4 E 8 F 7 G 2 H 1 5 10 11
Agg. Res
110
Sum of Sq 81
121
100
1104
Gantt Chart
Final result A 9 B 3 C 6 D 4 E 8 F 7 G 2 H 1 5 10 11
Agg. Res
110
Sum of Sq 81
121
100
1104
The sum of squares of the resource usage

21. Resource Levelling (resource limited schedule)
In generally resource levelling can be considered as an optimization problem for project scheduling as shortest as possible within the limited resource usage
In this context we can apply LP model and simple heuristic approaches for analyzing resource levelling problems.
However LP is not so efficient for larger networks such as more that 200 activities and need more precise data. Whereas heuristics can be more common approach

22. Resource Levelling (resource limited schedule)
Let’s have an example.
Activity
Predecessor
Duration (days)
Man power A - 1 7 B 4 C 3 D 2 E 5 F 8 G H 6 I
G, H 9 J
I, E 10
In this example we have to produce resource-leveled project schedule
And the resource availability can not be exceeded by 10 persons in each time period of a project

24. Resource Levelling (resource limited schedule)
Our main objective of this example is to obtain a feasible schedule within the limit of 10 men
To do this we need to use some simple heuristics as follow:
Activities with the minimum amount of slack
Activities with the smallest duration
Activities with the lowest activity identification number
Activities with the most successor tasks
Activities requiring the most resources

25. Resource Levelling (resource limited schedule)
But in this lecture I would like to introduce you Wiest’s heuristic for resource allocation and this procedure is based on following 3 simple rules of thumb.
To allocate resources serially in time. That is, start on the first day and schedule all activities possible, then do the same for the next day and so on
To give preference to the activities with the smallest slack when several activities compete for the same resources
To reschedule non-critical activities, if possible, to free resources for scheduling critical activities

26. Resource Levelling (resource limited schedule)
If we proceed systematically day by day as mentioned in the first heuristic, following actions can be done in this example.
Days
Action 1
Eligible set of Activities – A7; Slack – 0; Can be assigned to the resource table at 7 units of resource 2
Eligible set of Activities – D3, C4, B1, E5; Slack – 0,0,3,4; Using 2nd heuristic, D, C, B, activities can be scheduled at 8 units and E activity delayed by 1 day 3
Eligible set of Activities – D3, C4, B1, E5; Slack – 0,0,3,3; D, C, B, activities are ongoing so no additional activities can be assigned on day 3 and E activity delayed by 1 day again. 8 units of resource remained same 4
Eligible set of Activities – C4, B1, H6, E5; Slack – 0,3,0,2; C, B activities ongoing and activity H become a candidate for placement. H activity is successor of activity D and it is critical. So we recall 3rd heuristic and reschedule activity B (non-critical) to schedule the critical activities C and H. In this case the previous procedures need to be rebuild without activity B. As a result activity B postponed by 4 days, then the resource load of the first 4 days going to be 7, 7, 7 and 10. 5
Eligible set of Activities – H6, G2, B1, E5; Slack – 0,0,0,1; H is ongoing, G is a critical and B is postponed but this activity has no slack time left, so it is going to be critical. Thus we can schedule G and B activities over and above the ongoing activity H. As a result resource load become 9 unit on day 5.

27. Resource Levelling (resource limited schedule)
Example cont
Days
Action 6
Eligible set of Activities – H6, G2, B1, E5; Slack – 0,0,0,0; H, G and B activities are ongoing activities and critical. This stage activity E also become critical. So we are forced to postpone the critical activity E by one day, thus project duration going to increase from the original 10 to 11. As well as resource load remain 9 unit on day 6. 7
Eligible set of Activities – B1, E5, I9; Slack – 1,0,1; in this case activity B will have 1 day of slack. Because we have postponed critical activity E by 1 day on day 6 and the project duration has become 11 which mean the slack time of all activities has increased by 1 day. But E still remain as critical in this situation. So activity B and E must be scheduled and resource unit become 6. 8
Eligible set of Activities – E5, B1, I9; Slack – 0,1,0; E and B are ongoing. Because it is not possible to schedule activity I along with activity E or B on day 8, for the second time we are forced to postpone a critical activity I (rule 3 not help us). As a result project duration increased to 12 days. E and B activities will be scheduled and resource unit will remain 6.
9-14
Eligible set of Activities – I9, F8; Slack – 0,2; I is critical, if you recall activity F that was a successor of activity B that is why this activity has 2 days of slack. Hence we schedule activity I on day 9 (its duration is 1 day), and subsequently activity J (10 resource unit required) will be scheduled on days 10, 11 and 12, followed by activity F on days 13 and 14. Thus final duration of project become 14 days

28. Resource Levelling (resource limited schedule)
Example cont.

29. Thank you for your attention