Critical Path Network

For projects of this magnitude and complexity it is essential that a critical path network (CPN) is established. 

This team will be required to operate at different intensity levels and to differing time scales, i.e. the occasional moderate pressure, but long-term involvement of the research/development group in conjunction with the more intense, short-term brief of the manufacturing division. These different time scales will have to be contained within a critical path network (CPN) once a launch window has been selected, in order to avoid a launch-restricting bottleneck. 

To overcome this limitation, in 1959 the Central Electricity Generating Board (CEGB) developed the critical path network diagram which we will now consider. 

A technique widely used by the industry is Critical Path Analysis (CPA or Network Analysis ) which is a method for systematically analysing the schedule of large projects, so that activities within a project can be phased logically, and dependencies identified. All activities are given a duration and the longest route through the network is known as the critical path. 

The coordination of this entire complex process is the province of project management, the objective of which is to ensure that all the necessary parts and components of a project mate up. This discipline in its modem form was first developed for the Polaris missile project in the 1960s. Its major tool that is familiar to pharmaceutical scientists is the network or PERT (Program Evaluation Review Technique) chart, as illustrated in Figure 1.2. This chart is a tool that allows one to see and coordinate the relationships between the different components of a project. One outcome of the development of such a network is identification of the rate-limiting steps, which, in aggregate, comprise the critical path (see Table 1.3 for a lexicon of the terms used in project management). 

Acronym for Critical Path Method. A network diagramming technique that places emphasis on time, cost, and the completion of events. 

FDA s Critical Path to New Medicinal Products, also known as the Critical Path Initiative, aimed at networking clinical trials through integrative informatics... 

We need to set up a network or arrow diagram based on a Critical Path Analysis of all the factors and activities which relate to coal mining and determine in a quantitative way what is required and what specifically has to be done and by whom in order to achieve a coal production level of 1 billion tons per year. 

Figure D18. Network Diagram of Product X Primary Tasks Critical Path...

The critical path for a project is that which determines the shortest time in which a project can be completed. It is of greatest value where there are sophisticated network diagrams, involving multiple parallel activities. 

When the series of activities is diagrammed, it can be seen that many possible paths exist between the start and the end. The critical path is defined as that path involving the desired (usually shortest) duration for completion of the project. The mathematical concepts of both PERT and CPM are normally of sufficient complexity that a digital computer must be used for the solution. By the appropriate network computations, a final sequential procedure is developed which gives the critical path that must be followed from the start to the end to complete the job in the most efficient manner in a given duration of time. 

Although project management was certainly applied in practice prior to the mid-1950 s, the development of the critical path method and the Project Evaluation and Review Technique (PERT) is considered to be the initiation of the modern practice of project management. The critical path method is a network analysis technique used to predict project duration by analyzing which sequence of activities or path most likely has the least amount of scheduling flexibility or... 

Network logic determines the relationship between the tasks or team member deliverables, either sequential (finish to start) or overlapping (start to start and/or finish to finish). There are numerous software packages available at low cost to support calculation of the critical path and float. However, the real challenge of project management tools is the creation of the project network based upon historical experience and team involvement. By definition projects are rmique and, in the pharmaceutical arena, each project is different. Therefore, the importance of team member involvement in the development, tracking, and adjustment of the project schedule is crucial to successful application of project management basics. 

Time constraints, expenses, and staffing do not play a predominant role in the current state of the AHEAD system. Nevertheless, they have to be considered in process management. Widespread project management systems like Microsoft Project offer functions like the computation of a critical path in an activity network, workload balancing for the staff or calculation of the aggregated expenses for (parts of) a project. Besides these available functions, project management systems offer additional views on the current project state, like the activity oriented Gantt-chart or diverse resource-oriented views. 

A full description is beyond the scope of this review, but it is noted that the topological method identifies other chemical features in the electron density. The union of all bond paths gives a bond path network that is normally in a 1 1 correspondence with the chemical bond network drawn by chemists. The bond paths for bonds in strained rings are curved, reflecting their bent nature. In Figure 6, we show the gradient paths in the molecular plane of cyclopropane. The C—C bond paths are distinctly bent outward. The value of the Laplacian at the bond critical point discriminates between ionic and covalent bonding." Maps of the Laplacian field reveal atomic shell structure, lone pairs, and sites of electrophilic and nucleophilic attack. The ellipticity of a bond measures the buildup of density in one direction perpendicular to the... 

The critical path is the path in the project network diagram that consumes the longest elapsed time. It is the path in which there is no extra time available to accommodate delays. This is in contrast to other paths, where float exists and can be used to accommodate delays. A delay in the critical path will result in a delay of the entire project. 

Network analysis can be used to describe the complicated precedence relationships between the activities of a large project. The resulting description can be used to determine a timetable for the activities and to predict a completion date for the project. Examples of network planning methods (or project planning methods) are the Critical Path Methods (CPM) and Performance Evaluation and Review Technique (PERT) (Chryssolouris 2006). 

The detail schedule should provide a calendar-based schedule of activities, tasks, and key events of the master schedule. The detail schedule should be used to track the progress of the technical effort. Detail schedule data should be used to construct a network of events, tasks, and activities to determine the critical path of the engineering efforts and to analyze variances to schedule. 

Project network techniques provide a means to determine the sequence of activities and their subsequent scheduling. Through a network analysis process, also referred to as CPM (critical path method) or PERT (programme evaluation review technique), constituent project activities are assembled into a logical, diagrammatic model, and then analysed in terms of time and resource. The planning sequence runs as follows ... 

By visualizing the components of a task or project and understanding the relationships between them, you will be prepared to apply the Critical Path Method, which is discussed in Chapter 6, or other network methods. In addition, partitioning a task or project into its component parts provides the basis for effective delegation, which is discussed in Chapter 4 and is another way to make effective use of your time. 

Beside a simple list of milestones or even tasks, two effective ways of presenting a detailed schedule are the bar or Gantt chart and the network diagram with a critical path. Examples of the list, bar or Gantt chart, and network diagram are presented in the next chapter. 

Figure 6.4 Network diagram used for the example application of the Critical Path Method.

There must always be at least one critical path. However, there could be two or more critical path segments in parallel through all or some of the network. Any delay in a critical activity automatically delays project completion the same amount unless some compensatory action is taken. The critical path is the longest path in terms of time. Time contingencies can be added to each activity or to the overall project. 

C. Perform the complete CPM process, including constructing the network, applying the CPM, highlighting the critical path, and developing the Gantt chart showing total floats. 

Clearly the complexity of most supply networks is such that in reality event management needs to be restricted to the critical paths in that network. Critical paths might be typified by such features as long lead times to react to unplanned events, reliance on single-source suppliers, bottlenecks, etc. 

It is this detailed level of supply chain understanding that is necessary if risk is to be mitigated and managed. For complex supply chains or where complete mapping of the entire network is not practical it would be appropriate only to look in detail at the critical paths - how these are identified is dealt with later. 

Path 1-3-4 is the longest path and is considered the critical path. At least one path in every project network is considered the critical path. It is critical because it is the longest path and any delay in any one of the activities in this path will cause the entire project to be... 

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