You have three options for buffer: project, feeding, and resource (Jaskowski et
ID: 335096 • Letter: Y
Question
You have three options for buffer: project, feeding, and resource (Jaskowski et al., 2011) Choose one or more types of buffers and explain where you would place each buffer, how much buffer you would include, and a brief explanation of each of your buffers (why you chose the type of buffer, why you chose the location in the schedule, and why you chose the duration of the buffer)?
What is the tradeoff to utilizing buffer?
How does the technique your lead planner used to estimate each step’s duration impact your decisions regarding buffer?
BACKGROUND INFORMATION
In this module, you will focus on process improvement and project management. In the article, Trade-off between robustness of a construction schedule and project completion time (Links to an external site.), the authors are searching for a best measure of robustness of schedule (Jaskowski, Biruk & Kowalski, 2011). Projects experience delays for a variety of reasons. Wouldn’t it be nice to be able to predict a schedule more accurately – yielding a robust schedule? You are the Project Manager for a mass transit project in Dhaka, Bangladesh. You have just received the draft schedule from your lead planner as shown in Figure 1.
Step A (Average time to complete - 12 hours, median time 10 hours Step B (Average time to complete -8 hours, median time 11 hours) Step D Average time to complete -8 hours, median time 11 hours Step E (Average time to complete - 25 hours, median time 22 hours) Step G (Average time to complete - 3 hours, median time 2.5 hours) Step C (Average time to complete -5 hours, median time 5 hours) Step F Average time to complete 10 hours, median time 11 hours)Explanation / Answer
Critical chain buffer management is a system of use of buffers of time within a project to ensure the project meets every deadline every time.
The importance of critical management of a project schedule is to ensure that project deadlines are met and put in place controls and checks to maximize the probability of successful implementation of the project. Let us understand the basic nature of each type of buffer and its importance. Project buffer is mostly a single buffer which is implemented to ensure the project deadline is definitely met. Feeding buffer relates to identification of parts within the chain where buffering becomes crucial to rule out delays and maintain project schedule. A resource buffer is more of an artificial buffer that serves as a warning system to assure that the project does not suffer due to non-availability of resources and is hence able to run as per schedule.
Since 72.5 hours is total median time for the entire project I would allocate a project buffer of 50% that would be 36 hours approximately. Also considering that step A and step E indicate that the actual time taken to complete this particular step could overshoot the median time I would like to create feeding buffer in both the steps for 50% of the required time each. That would be first Step A an extra 5 hours and for Step E an extra 11 hours. I would like to include resource buffer after Step E as this is the point which is crucial for both step F and step G and since it is also critical step in terms of average time required being more than the time allotted it is the point which would require maximum control and buffering in the entire process. This is also the point at Step B where excess time from it would be used as a buffer if needed for Step C as Step B needs 8 hours but has 11 hours.
The trade off to buffering is both improvement of quality of output as well as the success of the overall solution offered. Buffering not only ensures that project quality is not compromised due to pressure to meet time deadlines while also provides stability to the project by aligning the time taken to the actual time provided. It also works as a control measure whereby any deviations are easily detected and corrected due to presnce of critical management of certain high risk steps.
A lead planner's technique vastly impacts the judgement for type of buffering and point of buffering both. As buffering depends entirely on the data provided by the planner of the project, it is essential to consider the methodology used by the planner before taking any decisions on buffering. Has he already provided buffering? How accurate is the calculation of time required for each step and what is the system followed? Is the system exact and uniform resulting in accurate requirements of time for each step? If not, what percentage of deviation can be expected? Has the planner correctly identified the sensitive steps requiring extra control or buffering? Hence, it is obvious that an accurate input from the planner only can result in perfect buffering.
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