SCHEDULE CONTROL CHAPTER 11 Chapters 9 and 10 established a baseline plan and a schedule, respectively for the consumer market study project. Once a project actually start’s, it’s necessary to monitor the progress to ensure that everything is going according to schedule. The key to effective project control is to measure actual progress and compare it to planned progress on a timely and regular basis and to take necessary action immediately. LEARNING OBJECTIVES This chapter will cover the details of controlling a project and will focus mainly on the critical role of controlling the scheduling to ensure that the work gets done on time. By mastering the concepts discussed in this chapter, you should be well prepared to help control your projects. You will become familiar with: Performing the steps in the project control process; Determining the effects of actual schedule performance on the project schedule; Incorporating project changes into the schedule; Calculating an updated project schedule; Controlling the project schedule. PROJECT CONTROL PROCESS The project control process involves regularly gathering data on project performance, comparing actual performance to planned performance, and taking corrective actions if actual performance is behind planned performance. Figure 11.1 illustrates the steps in the project control process. It starts with establishing a baseline plan that shows how the project scope (tasks) will be accomplished on time (schedule) and within budget (resources, costs). A regular reporting period should be established for comparing actual progress with planned progress. During each reporting period, two kinds of data or information need to be collected: 1.Data on actual performance. This includes The actual time that activities were started and/or finished The actual costs expended and committed 2.Information on any changes to the project scope, schedule, and budget. These changes could be initiated by the customer or the project team, or they could be the result of an unanticipated occurrence such as a natural disaster, a labor strike, or the resignation of a key project team member. It should be noted that once changes are incorporated into the plan and agreed on by the customer, a new baseline plan has to be established. The scope, schedule, and budget of the new baseline plan may be different from those of the original baseline plan. It is crucial that the data and information discussed above be collected in a timely manner and used to calculate an updated project schedule and budget. Once an updated schedule and budget have been calculated, they need to be compared to the baseline schedule and budget and analyzed for variances to determine whether a project is ahead of or behind schedule and under or over budget. If it is determined that corrective actions are necessary, however, decisions must be made regarding how to revise the schedule or the budget. These decisions often involve a trade-off of time, cost, and scope. In general, the shorter the reporting period, the better the chances of identifying problems early and taking effective corrective actions. If a project gets too far out of control, it may be difficult to achieve the project objective without sacrificing the scope, budget, schedule, or quality. Project management is a proactive approach to controlling a project, to ensure that the project objective is achieved even when things don’t go according to plan. EFFECTS OF ACTUAL SCHEDULE PERFORMANCE Throughout a project, some activities will be completed on time, some will be finished ahead of schedule, and others will be finished later than scheduled. Actual progress– whether faster or slower than planned- will have an effect on the schedule of the remaining, uncompleted activities of the project. Specifically, the actual finish times (AF) of completed activities will determine the earliest start and earliest finish times for the remaining activities in the network diagram, as well as the total slack. Figure 11.2 is an AIB network diagram for a simple project. This example illustrates how the actual finish times of activities have a ripple effect,altering the remaining activities earliest start and finish times and the total slack. INCORPORATING PROJECT CHANGES INTO THE SCHEDULE Changes might be initiated by the customer or the project team, or they might be the result of an unanticipated occurrence. Here are some examples of changes initiated by the customer: A home buyer tells the builder that the family room should be larger and the bedroom windows should be relocated. A customer tells the project team developing an information system that the system must have the capability to produce a previously unmentioned set of reports and graphics. These types of changes represent revisions to the original project scope and will have an impact on the schedule and cost. When the customer request a change, the contractor or project team should estimate the impact on the project budget and schedule and then obtain customer approval before proceeding. If the customer approves the proposal revisions to the project schedule and budget, any additional tasks, revised duration estimates, and material and labor costs should be incorporated. Some changes involve the addition of activities that were overlooked when the original plan was developed. Other changes become necessary because of unanticipated occurrences, such as a snowstorm that slows down construction of a building. Still other changes can result from adding more detail to the network diagram as the project moves forward. Any type of change—whether initiated by the customer, contractor, project manager– will require a modification to the plan in terms of scope, budget, and/or schedule. UPDATING THE PROJECT SCHEDULE Network-based planning and scheduling allows project schedules to be dynamic. Because the network plan (diagram) and schedule (tabulation) are separate, they are much easier to update manually than a traditional Gantt chart. Once data have been collected on the actual finish times of completed activities and the of any project changes, an updated project schedule can be calculated. These calculations are based on the methodology explained in Chapter 10: The earliest start and finish times for the remaining, uncompleted activities are calculated by working forward through the network, but they are based on the actual finish times of completed activities and the estimated durations of the uncompleted activities; The latest start and finish times for the uncompleted activities are calculated by working backward through the network. As an illustration of the calculation of an updated schedule, let’s consider the network diagram shown in Figure 11.3 for the consumer market study project. The network diagram in Figure 11.3 incorporates the above information. Figure 11.4 shows the updated schedule. APPROACHES TO SCHEDULE CONTROL Schedule control involves four steps: 1.Analyzing the schedule to determine which areas may need corrective action. 2.Deciding what specific corrective action should be taken. 3.Revising the plan to incorporate the chosen corrective actions 4.Recalculating the schedule to evaluate the effects of the planned corrective actions. If the planned corrective actions do not result in an acceptable schedule, these steps need to be repeated. The schedule analysis should include identifying the critical path and any paths of activities that have a negative slack, as well as those paths where slippages have occurred compared with the previously calculated schedule. A concentrated effort to accelerate project progress must be applied to the paths with negative slack. Corrective actions that will eliminate the negative slack from the project schedule must be identified. Remember, the slack for a path of activities is shared among all the activities on that path. Therefore, a change in the estimated duration of any activity on that path will cause a corresponding change in the slack for that path. When analyzing a path of activities that has negative slack, you should focus on two kinds of activities: 1. Activities that are near term (that is, in progress or to be started in the immediate future). 2.Activities that have long duration estimates. There are various approaches to reducing the duration estimates of activities. One obvious way is to apply more resources to speed up an activity. Reducing the scope or requirements for an activity is another way to reduce its duration estimate. Increasing productivity through improved methods or technology is yet another approach to reducing activities durations. Once specific corrective actions to reduce the negative slack have been decided on, the duration estimates for the appropriate activities must be revised in the network plan. In most cases, eliminating negative slack by reducing durations of activities will involve a trade-off in the form of an increase in costs or a reduction in scope. The key to effective schedule control is to aggressively address any paths with negative or deteriorating slack values as soon as they are identified, rather than hoping that things will improve as the project goes on. Project meetings are a good forum for addressing schedule control issues. SCHEDULE CONTROL FOR IS DEVELOPMENT Among the changes that commonly become necessary during IS development projects are the following: Changes to input screens; Changes to reports; Changes to on-line queries; Changes to database structures; Changes to software processing routines; Changes to processing speeds; Changes to storage capacities; Changes to business processes; Changes to software resulting from hardware upgrades or, conversely, hardware upgrades resulting from the availability of more powerful software. AN IS EXAMPLE: ABC OFFICE DESIGNS (CONTINUED) Figure 11.5 and 11.6 show the updated network diagram and project schedule, respectively, after these changes have been incorporated. Notice that because of the above occurrences, the critical path now has a total slack of 0. PROJECT MANAGEMENT SOFTWARE Virtually all project management software packages allow you to perform the control functions identified in this chapter. All network diagrams, tables, and reports produced by the software will be updated to reflect the most recent information. We assumed that the resources required to perform the individual activities would be available when they were needed. These resources can include people, equipment, machines, tools, facilities, and space. In many projects, the amounts of the various types of resources available to perform the project activities are limited. Sev-l act-s may require the same res-s at the same time, and there may not be sufficient res-es available to satisfy all the demands. In a sense, these activities are competing for the use of the same resources. If sufficient resources are not available, some activities may have to be rescheduled for a later time when resources are available for them. Therefore, resources can constrain the project schedule. They can also be an obstacle to completing the project within budget if it is determined that additional resources are needed to complete the project on time. LEARNING OBJECTIVES This chapter covers several approaches to incorporating resource considerations into the project plan and schedule. You will become familiar with: taking resources constraints into account when developing a network diagram; LEARNING OBJECTIVES determining the planned resource utilization for a project; leveling the use of resources within the required time frame of the project; determining the shortest project schedule with the limited resources available. RESOURCE-CONSTRAINED PLANNING One way to consider resources is to take them into account when drawing the logical relationships among activities in the network diagram. Network diagram illustrate the technical constraints among activities. Activities are drawn in a serial relationship because, from a technical standpoint, they must be performed in that sequence. Figure 12.1 shows three house-building activities. The sequence of activities can be drawn to reflect the availability of a limited number of resources. Part (a) of Figure 12.2 shows that, technically, three activities could be performed concurrently. Suppose, that there is only one person available to do all the painting. That is, although technically all three activities could be done concurrently, they will have to be performed in series since only one painter is available to do all three. To incorporate this resource constraint, the diagram will have to be drawn as shown in part (b) of Figure 12.2. This example illustrates how resource limitations can be considered when a network plan is drawn. PLANNED RESOURCE UTILIZATION If resource are to be considered in planning, it’s necessary to indicate the amounts and types of resources needed to perform each activity. Figure 12.3 is a network diagram for a painting project. Using the information in Figure 12.3, we can prepare a resource utilization chart as shown in Fig.12.4, which indicates how many pointers are needed each day. It should be noted that the resource utilization charts shown in Figures 12.4 and 12.5 are based on each activity’s earliest start time. Such resource utilization charts are said to be based on an as-soon-as possible (ASAP) schedule. Resource utilization charts-based on each activity’s latest start time are said to be based on as-late-as-possible (ALAP) schedule. RESOURCE LEVELING Resource leveling, or smoothing, is a method for developing a schedule that attempts to minimize the fluctuations in requirements for resources. This methods levels the resources so that they are applied as uniformly as possible without extending the project schedule beyond the required completion time. Resource leveling attempts to establish a schedule in which resource use is made as level as possible without extending the project beyond the required completion time. Let us look at the painting project in Figures 12.3, 12.4, and 12.5 to determine whether resource utilization can be leveled. Figures 12.3 and 12.4 show that the critical path for the project is made up of two activities and is 12 days long. Looking at Figure 12.4, we can see that two alternative actions could be taken to level the daily resource requirements for painters: Alternative 1.Delay the activity with the most positive slack-”Basement rooms” (+8 days slack) – by 6 days so that it will start after “Bedrooms” is finished. Alternative 2. Delay “Bedrooms” so that it will start on day 4, after “Basement rooms” is completed. This alternative will use the same painter to first paint the basement rooms and then paint the bedrooms. Figures 12.6 and 12.7 illustrate the resource profile for the resource-leveled schedule if we choose alternative 1. Comparing Fig.12.6 with Fig. 12.4, we see that the earliest start time for “Basement rooms” has been delayed from time 0 to day 6, and its earliest finish time is now day 10 rather than day 4. Fig.12.7 shows a more uniform utilization of painters than Fig. 12.5, except for days 11 and 12, which remain the same RESOURCE-LIMITED SCHEDULE Resource-limited schedule is a method for developing the shortest schedule when the number or amount of available resources is fixed. This method is appropriate when the resources available for the project are limited and these resource limits cannot be exceeded. This method will extend the project completion time if necessary in order to keep within the resource limits. It is an iterative method in which resources are allocated to activities based on the least slack. When several activities need the same limited resource at the same time, the activities with the least slack have first priority. If resources are left over, the activities with the second least slack have the next priority, and so forth. If other activities need the resource but the resource has been totally allocated to higher-priority activities , the lower – priority activities get delayed; as their slack becomes worse, they eventually move up the priority ladder. This delaying of activities can extend the project completion time. Figure 12.8 illustrates what would happen if only a limited number of painters-two- were available to do the painting project. When we push down on the level of resources because no more than two painters can be used, we push out the project completion time. Let us apply resource-limited scheduling to the painting project shown in Fig.12.3. Fig.12.9, which is the same as Fig.12.4, is our original resource utilization; it shows a project completion time of 12 days. Let us now assume, however, that we’re limited to only two painters. Fig.12.9 shows that, as the project starts, three activities require a total of four painters(“first floor rooms”, “basement rooms”,and “bedrooms”). Only two painters are available, though, so they will be allocated to the activities based on a priority determined by slack. Since all the available resources are assigned to “first floors rooms” from time 0 through day 8, the other two activities (“basement rooms” and “bedrooms”) will have their starts delayed until after day 8. This first resource allocation is shown in Fig.12.10. The result of this first iteration of allocating the painters is extension of project completion from day 12 to day 14 because of the delay of ‘bedrooms”. The second resource allocation is shown in Fig.12.11. The result of this second iteration of allocating the painters is another extension of project completion , this time from day 14 to day 16, because of the delay of “basement rooms”. And there is still a problem on days 13 and 14 because the resource requirements exceed the limit of two painters. The third resource allocation is shown in Fig.12.12. As a result of this third iteration of allocating the painters, the project completion time is still 4 days beyond the required project completion time, but all the activities have been scheduled to start and finish so as to stay within the limit of two painters. PROJECT MANAGEMENT SOFTWARE Project management software provides excellent features for handling resource considerations within a project. Most software packages allow you to create and maintain a list of resources that can be accessed by all of the tasks within a project. The list typically allows you to store the resource name,maximum number of units available, standard and overtime rates, and costs. The software will typically inform the user if any resources have time conflicts or if any resources are over allocated within a project or among concurrent projects. Tables and graphs of resource usage are often available. To resolve any conflicts or to level, or smooth, the resources, the software typically provides two option. The first is to correct the situation manually.With this option, the user modifies the task information and requirements and/or the resource list and then sees whether the situation has been resolved. The second option is to allow the software to perform this process automatically. If the automatic process is selected, the software typically asks the user whether the deadline can be extended if that’s the only way to resolve the conflict or smooth the resources. Figure 12.13 shows the differences between resource leveling and resource-limited scheduling.
Posted on: Fri, 14 Jun 2013 03:29:24 +0000
Trending Topics
Recently Viewed Topics
© 2015