An Extension for Further Reducing Input Requirements
and Sean Shanahan
Oregon State University
A major problem in using CPM/PERT planning and scheduling techniques is the cost of the management effort needed to analyze project components and resource levels, develop networks, develop schedules, and collect error-free data. The development of high-powered, computerized algorithms has done little to reduce these costs and in some cases may actually increase them. The costs are of such a magnitude that many project managers have been reluctant to utilize network techniques, especially in smaller, less financially robust organizations.
One method devised to reduce these costs is the Standardized Network. Standardized Networks (SN) do indeed reduce costs by reducing system input requirements and making the planning and scheduling process more routine. The concept of SN is not new. Contractors who build high rise apartments, offices, and hotels often use the same (i.e., standard) network for each floor since most floors are typically similar. The primary benefit of this approach is that the planning process tends to be routinized, thus shifting responsibility to lower levels of management. In addition, input requirements to support the computer system which generates the CPM/PERT output are significantly reduced. In short, costs are cut and data are gathered closer to the production level. Project managers in fields other than high rise construction have recognized these benefits but, unfortunately, relatively few project organizations actually have standard projects. Most have a great degree of variability from one project to another.
Some notable exceptions do exist. A state highway department has found the SN concept useful for new highway design and construction. A custom sawmill builder uses SN to schedule new fabrication orders, to determine labor requirements, and to set budgets. A designer and fabricator of water purification plants uses SN for scheduling labor and determining delivery dates. Some accounting firms use SN in their auditing process. A landscaping organization uses SN for planning relatively standard landscape projects. It is significant to note that the majority of these applications are employed on a manual basis without computer assistance. The final example is a national forest organization which plans and schedules approximately 150 timber sales per year. This organization found that three computerized, standardized networks could handle about 99 percent of the projects which occurred.
Extending the Standardized Network Concept
The national forest example gave rise to the extension developed in this study. The basic idea is that although a single standardized network is inadequate in most project organizations, a small number, for example three, can deal with virtually all projects. The logical extension is for an organization to develop a relatively small number of general, or standardized, networks which cover the majority of all projects. Each project, then, is a specific subset of one of the general networks. This procedure would enable a much larger group of project organizations to reap the benefits of SN; for example, organizations which do the same kind of work, but each specific job has slightly different characteristics. Potential users will not only include large project organizations, but will include small organizations typically referred to as job shops, which to date have found CPM network techniques too cumbersome.
In order to implement this extension, the major requirement is to develop the set of master networks which will cover the majority of the projects expected to occur over a specific planning period. As a guideline for determining an organization’s suitability for utilizing this extension, it is suggested that not more than ten general standard networks be used to cover at least 90 percent of the projects during a two-to-five year period. Each activity of each master network is given a description and assigned the resource categories needed to accomplish it. It is important to note that once the initial set of networks has been developed, no further network development takes place. This is significant since a great deal of managerial effort is used in determining the structure of a network.
The utilization of the master networks is quite straightforward. When a project is received, the manager reviews it, compares the project to the set of master networks, and selects the appropriate network. Next the activities from the master network which are applicable to this project are identified. Each activity is then assigned an activity duration. Finally, each activity is assigned a resource category and allocated the necessary quantity of that resource needed to complete the activity within the specified duration.
Front-End Computer Program
While using standardized networks with the national forest case, it became evident that a significant portion of the cost of using CPM systems was developing networks and error-free computer input. To reduce the costs, a “front-end” computer program was written. The output of this program becomes the input for a standard CPM/PERT planning and scheduling program—thus it is called a front-end program. The program stores the master network(s) and activity and resource descriptions in files. It uses the activities, times, and resources selected by the project manager to develop a numbered network and error-free input data for the standard CPM/PERT computer program. Figure 1 shows the sequence of events which occurs when a front-end program is used.
To measure the reduction in computer input requirements, previously analyzed projects for four organizations were tested. The projects involved timber sales, auditing, landscaping, and the design and construction of water purification systems. After the master network information was submitted to the front-end program, the data requirements (punched or typed) for specific projects were reduced 87.0%, 88.9%, 89.9%, and 90.3%, respectively, over the use of a standard CPM/PERT program. The input requirements for both systems are shown in Table 1.
|STANDARDIZED NETWORK||STANDARD CPM PROGRAM|
|1. Master network activity number|| |
1. Project network
|2. Activity duration|| |
2. I-J nodes (or activity number and predecessor and successor activities)
|3. Number of resource required|| |
3. Activity duration
4. Activity description
5. Number of resource required
6. Resource description
The savings were consistent on all projects tested and suggest that computer input requirements will be reduced approximately 88% for users of standardized networks and a front-end program which organizes the input into a network format for a CPM/PERT program.
Summary of Advantages
The advantages which accompany the use of standardized networks in multiproject organizations are:
1. Eliminates the need to develop and number networks, which usually require considerable training and expertise. A network can easily be drawn from the event numbers.
2. Reduces computer input requirements approximately 88 percent. Activity and resource skill descriptions are eliminated; the descriptions are uniform throughout the organization.
3. Allows the planning process to be shifted to lower management levels. Allows for management by exception.
4. Reduces the planning time needed for each project.
5. Gives project managers a graphic tool to communicate with each other. Output content and formats are more uniform; therefore communication within and between organizations is facilitated.
6. Several sets of standardized networks can be used concurrently.
7. Reduces input errors due to reduction of input data.
These advantages are significant. Together they greatly reduce the costs incurred when using CPM/PERT techniques for planning and scheduling projects.
Although standardized networks do require a certain amount of repetition to be applicable, the use of several standard networks holds tremendous potential to significantly reduce management effort associated with CPM/PERT techniques. Standardized networks facilitate the routinizing of project planning and scheduling, thus enabling true management by exception. The addition of front-end programs will reduce those efforts even further. Together these two developments will provide a project manager with the opportunity to actually use the results of the techniques.
The extension of using more than one standardized network concurrently opens the use of CPM/PERT techniques to other, non-project organizations. The biggest beneficiary would seem to be job-shop operations. They are certainly project-oriented but typically have many relatively small projects during a given time span. These organizations could gain the benefits of network techniques.