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Example 2.23: Resource Driven Durations and Resource Calendars

This example illustrates the effect of resource driven durations and resource calendars on the schedule of a project involving multiple resources.

In projects that use manpower as a resource, the same activity may require different amounts of work from different people. Also, the work schedules and vacations may differ for each individual person. All of these factors may cause the schedules for the different resources used by the activity to differ from each other.

Consider a software project requiring two resources: a programmer and a tester. A network diagram displaying the activities and their precedence relationships is shown in Figure 2.8.

Some of the activities in this project have a fixed duration, requiring the same length of time from both resources; others require a different number of days from the programmer and the tester. Further, some activities require only a fraction of the resource; for example, `Documentation' requires only 20 percent of the programmer's time for a total of two man-days. The activities in the project, their durations (if fixed) in days, the total work required (if resource-driven) in days, the precedence constraints, and the resource requirements are displayed in Output 2.23.1.

   proc cpm data=software out=sftout ressched=rsftout
            date='11apr94'd interval=weekday resout=rout;
      act act;
      succ s1 s2;
      dur dur;
      res progrmr tester / work=mandays
                           rschedid=Activity;
      id Activity;
   run;

The individual resource schedules, as well as each activity's combined schedule, are saved in a Resource Schedule data set, RSFTOUT, requested by the RESSCHED= option on the CPM statement. This output data set (displayed in Output 2.23.2) is very similar to the Schedule data set and contains the activity variable and all the relevant schedule variables (E_START, E_FINISH, L_START, and so forth).

The DURATION variable,dur, indicates the duration of the activity for the resource identified in that observation. For resources that are of the driving type, the WORK variable, mandays, shows the total amount of work (in units of the INTERVAL parameter) required by the resource for the activity in that observation. The variable R_RATE shows the rate of usage of the resource for the relevant activity. Note that for driving resources, the variable dur is computed as (mandays / R_RATE).

A Gantt chart of the schedules for each resource is plotted in Output 2.23.3.

   proc cpm data=software resin=resin
            out=sftout1 resout=rout1 
            rsched=rsftout1
            date='11apr94'd interval=weekday;
      act act;
      succ s1 s2;
      dur dur;
      res progrmr tester / work=mandays
                           obstype=otype
                           period=per
                           rschedid=Activity;
      id Activity;
   run;

   proc cpm data=software resin=resin2
            caledata=calendar
            out=sftout2 rsched=rsftout2
            resout=rout2
            date='11apr94'd interval=weekday;
      act act;
      succ s1 s2;
      dur dur;
      res progrmr tester / work=mandays
                           obstype=otype
                           period=per
                           rschedid=Activity;
      id Activity;
   run;

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