Resource Scheduling

• Time Limited Scheduling

• Resource Limited Scheduling

The Need for Resource Scheduling:

• The previous Project Scheduling methods that we have covered have not considered the constraint of resources.

• Generally, there are two types of projects…..

1. Projects that MUST meet a certain deadline and have ‘unlimited’ resources in order to meet this. This would use Time Limited Scheduling.

2. Projects that have limited availability of the required resources, however the project deadline is more flexible. The would use Resource Limited Scheduling.

Note: if a project has both limited time and resources, the project manager must initially assume that one or the other is flexible. OR, renegotiations will need to take place.

Time Limited Scheduling

Objectives:• To determine exactly what resources the

project requires, and make these resources available for when they are needed.

• To use each resource as efficiently as possible– Resource Smoothing: this defines the act of

maximising resources efficiency. Despite having ‘umlimited’ resorurces, it is still necessary to try to keep costs down as much as possible.

The Resources Loading Chart:Consider the following example which is adapted from Field & Keller ‘Project Management’ 1998:

Activity Description Staff DurationEarliest Start

Time FloatLatest Finish

Time

A Prepare offices 2 12 0 0 12

B Procure equipment 2 8 0 4 12

C Design tests 1 5 0 17 22

D Install equiptment 4 10 12 0 22

E Test system 3 10 22 0 32

F Train users 1 5 12 15 32

• We will build the previous information into a ‘Resource Loading Chart’

Observations:

• From the previous slide’s graph we can immediately tell how many staff are needed at any one time.

• For example – in week 10, we can identify that only 2 staff members are required. Whereas in week 14 there are 5 staff members required.

• Note: The bottom row of the graph could also be described as the ‘critical path’. Each of these items as Float=0. This row can be described as the Base Line.

• The method of creating this chart, by positioning one activity at a time, is called Serial Scheduling.

Resource Levelling:

• As identified in the previous slides, our chart contains ‘extreme peaks’. For example, weeks 1-5.

• Resource levelling helps to avoid this.• As we have several activities which contain

float, we can try to move these activities to ‘level’ out the staff distribution:

• Obviously the below still isn’t ideal as we still have a ‘peak’ during week 13. However we have levelled s much as possible, and in turn we have reduced costs.

Resource Limited Scheduling

Objectives:

• To adjust the project’s time to adapt to fixed level of resources.

• In the previous example, we realised it would take 5 staff to create the office in 32 weeks.

• Now, let’s consider how long it would take if the staff level were fixed at 4.

Parallel Scheduling:

Definition: Starting at the beginning of a project and considering all the eligible activities, in a parallel manner.An eligible activity would be one which could be started if the resources were available.

Let’s re-consider the example….

Activity Dependency Staff Duration Latest Start Time Float Latest Finish Time

A N/A 2 12 0 0 12

B N/A 2 8 4 4 12

C N/A 1 5 17 17 22

D A and B 4 10 12 0 22

E C and D 3 10 22 0 32

F A and B 1 5 27 15 32

Have a go at plotting the chart with the strict resource limit of 4:

The Result…..

Further Reading:– Time Limited Scheduling

• Field & Keller Chapter 3.4, ‘Project Management’

• Moder et al (1983)– Resource Limited Scheduling

• Kerzner Chapter 12•