A network is the arrangement of all activities (and, in some cases, events) in a project arrayed in their logical sequence and represented by arcs and nodes. This arrangement (network) defines the project and the activity precedence relationships. Networks are usually drawn starting on the left and proceeding to the right. Arrowheads placed on the arcs are used to indicate the direction of flow- that is, to show the proper precedences. Before an event can be achieved, all activities that immediately precede it must be completed. To transform a project plan into a network, one must know what activities comprise the project and, for each activity, what its predecessors or successors are. An activity can be in any of these conditions: (1) it may have a successor but no predecessor; (2) it may have a predecessor but no successor (3) it may have both predecessors and successors. The interconnections depend on the technological relationships described in the Work Breakdown Structure (WBS). An event represents an instant in time when each and every predecessor activity has been finished. An event is the result of completing one or more activities. It is in terms of an identifiable end state that occurs at a particular time. An activity is a specific task or set of tasks that are required by the project, use up resources, and take time to complete. Activities are critical insofar as, if delayed, they will delay the completion of the project. The critical activities in real-world projects typically constitute less than 10 percent of the total activities. A project’s critical path is understood to mean that sequence of critical activities (and critical events) that connects the project’s start event to its finish event and which cannot be delayed without delaying the entire project. A path is the series of connected activities (or intermediate events) between any two events in a network. Originally, the critical path method (CPM) was designed for construction projects and has been generally embraced by the construction industry. In CPM, activities can be “crashed”, also known as expedited, at extra cost to speed up the completion time.
Once again, I draw on my professional experience applicable to project management being residential solar panel system installation. Receiving permits is a crucial element of the critical path. After the client has signed the contract and is fully agreed to installation, the project management team is dependent on receipt of permits from the county or city to start the construction. Without the permits, the project cannot go on. Therefore, receiving the permits is an aspect of the critical path. With a client who is committed to solar and does not pose any delays before contract signing, the receipt of county/city permits can be the largest reason for delay. In this case, when the permits are reviewed and approved quickly, the project typically ends early. In other cases, with all other described conditions constant, when the permits are reviewed and approved slowly, the project typically ends late. It is important to convey to the sponsor that the time it takes to receive permits back from the city/county is beyond my control. I used to provide a range of time it takes to receive the permits. That way, I set proper expectations for the sponsor.
Source:
Meredith, Jack R., Scott M. Shafer, and Samuel J. Mantel. Project Management: A Strategic Managerial Approach. 10th ed. Hoboken, NJ: Wiley, 2018.
Comment by Professor Pasquini:
An early start to the thread !! Permitting is always an unknown in time and can delay a project. Generally some buffer/extra time is added to the permit WBS element.
My Response:
Hi Professor Pasquini,
Thanks for explaining the fluctuation of the permitting timeframe. It is going to be useful in the process of refining the WBS. It is interesting to consider, not only large-scale potential sources of delay to the critical path but also, variations in the amount of buffer/extra time is needed depending on the project. That said, it may be beneficial for a PM to review the first deliverable for the purpose of understanding which aspects of the project are going to require permits. It is important to add permits to the budget. Further, counties differ in permitting standards and review time. So, it is worth it to research the typical processing lengths ahead of time.
Comment by Tyler Berry:
Hi Mary,
That is a great comment about your past work experience and the permits for the solar paneling. I like how you provided the client with a range of time it takes to receive the permits to hopefully avoid delays. It talks about in the book how it is important to be meticulously honest with your estimates. They did not say accurate with your estimates because that is impossible. You would not want to create a false early deadline for your client because you were too optimistic with your time estimate on the permits being completed. Sounds like you are doing project management very well with your honest time estimates!
My Response:
Hi Tyler,
Yes, providing a range of timing to the client builds trust. In terms of communicating with the sponsor about the critical path, it is essential for the PM to be as transparent as possible. Also, when providing a range of times about permitting, I can not only equip the client for the worst case scenario, but also with the best case scenario. That way, in the case permits do not take so long to return from the city/county, the client may be more prepared to move forward with the project and make decisions needed for steps down the road after permitting. I figure it would also be useful to explain to the sponsor how the estimates were derived. It is beneficial to be on the same page.
Comment by Jennie Horton:
Mary,
This was a great breakdown of what goes into determining the critical path. I agree that setting expectations with the client is very important. As the saying goes, under-promise and over-deliver when possible. Through understanding the steps necessary to complete the permitting process, you were able to give your clients a realistic idea of the completion date.
My Response:
Hi Jennie,
You make a phenomenal point in saying, insofar as the PM is familiar with the details of the permitting process, the customer has a pleasant experience. A PM communicating the details of certain outsourced services within a project to a sponsor makes the latter feel informed and, as a result, way more comfortable.
Comment #2:
Original Post by Alexis McClintock:
The critical path analysis identifies the longest network of activities that must be completed to complete the project. The network is the arrangement of all the steps that are to be completed. This network demonstrates the relationships between the different activities (successors & predecessors) and the path of when activities are to be completed. Figure 8.16 shows a network and identifies the critical path or longest path to the end; in this case the critical path is a,d,j (Meredith et al. 2018).
Delays in the other paths are not critical because there is a smaller chance that the delay would be significant enough to delay the project complete. A delay in the critical path is guaranteed to delay the overall project completion. When determining critical paths it is necessary to look at all predecessor activities leading to the completion of the path to ensure you are accurately identifying the critical path (Meredith et al. 2018).
I have no personal experience using any of these scheduling methods. Nor experience scheduling such a complex schedule. I can see how using these methods can help organize a project schedule. While that can get complex they also look pretty straight forward, and I like that the method applied in Figure 8.16 included the late start, and late finish estimates. I can also see how identifying the critical path can help focus effort to ensure the critical path does not exceed the earliest finish date.
References
Meredith, Jack R., Scott M. Shafer, and Samuel J. Mantel. Project Management: A Strategic Managerial Approach. 10th ed. Hoboken, NJ: Wiley, 2018.
My Comment:
Hi Alexis,
Excellent post. Your definition of the critical path being the longest network of necessary activity is useful as we approach the assigned problems for this week focused on completion time and probability. I agree the critical path exemplifies the importance of scheduling because certain activities are reliant on another. Considering delays in the other paths are not critical, analysis of the critical path informs a PM which activities to allocate resources towards. I figure pouring additional resources into critical path activities can significantly improve the overall project’s efficiency.
Response Alexis McClintock:
I keep thinking about how the best strategies are to balance what is being allocated to the critical path versus the others. This questions is necessarily directed at you but I am curious if there are instances in which the critical path is no longer the critical path. Is there a possibility for a secondary path to become a critical path due to inadequate resource allocation or other factors.