UT Knoxville BUAD 341 - Critical Chain Project Management (4 pages)

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Critical Chain Project Management



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Critical Chain Project Management

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Beginning an example of CCPM.


Lecture number:
22
Pages:
4
Type:
Lecture Note
School:
University of Tennessee
Course:
Buad 341 - CBM II: Lean Operations
Edition:
1
Unformatted text preview:

BA341 22nd Edition Lecture 22 Outline of Last Lecture I Continuing the problem using PERT II Cost Time Trade offs and Project Crashing III Time Cost Trade offs IV Reducing Project Duration V Some Time Cost Models VI Critical Path Models VII Crashing Outline of Current Lecture VIII Project crashing IX Critical Chain Project Management X Step by step example Current Lecture Project Crashing Critical path for crashed schedules Minimum Cost of crashing project to minimum duration o Step 1 replace all activity normal durations with their crashed durations o Step 2 identify the critical path These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Step 3 Relax non critical activities in decreasing order of their slopes i e what is the point of fully crashing non critical activities o Finally the minimum cost is the sum of the Cost of crashing the critical activities down to their minimum durations 40 A 60 B 35 E 135 Cost of crashing activity D 1 day from 4 to 3 days 30 135 30 165 Critical Chain Project Management There are several human behavior laws that tend to jeopardize task and overall project durations o Parkinson s Law o 3 Minute Egg Rule o Student Syndrome o Multitasking Addressing them is especially important when there are limited recourses available for a project Let s consider an example Assume the following project where the letters represent resources Further assume that activity durations have been determined in the traditional way i e have been individually padded for safety In this example letters represent recourses o There is one task that requires the resource V o There is one task that requires the resource W o There is one task that requires the resource Y o There is one task that requires the resource Z o And there are two tasks that require the resource X The resource X can work only on 1 task at a time Step 1 Use Aggressive but possible times ABPT o According to the CCPM the first step is to use aggressive but possible times ABPT for task durations o Aggressive but possible times equal to half of traditionally estimated task durations For example the traditional time estimate for the task that requires the resource V was 12 days ABPT estimate is 12 2 6 days Step 2 Identify the critical chain The longest sequence of dependent events that prevents the project from completing sooner based on ABPT durations o The correspondent of the constraint in a project environment o Task and resource dependencies are key in identifying the critical chain o o This diagram shows the rearrangement of the tasks Now we do not have any resource conflict We find the project duration by finding the longest path It s Y X X Z And it s duration is 8 10 10 12 40 days o Task and resource dependencies are key in identifying the critical chain In this situation we call the longest path the critical chain o Note if we had unlimited resources we would not to consider rearranging tasks and we would just use the critical path method Step 3 Add the Project and Feeding Buffers o Project Buffer added at the end of the project protects the final project completion date from variations in the duration of critical chain activities The size of the project buffer equals to the half of the safety removed from the tasks that make the critical chain o Feeding Buffer placed at the merging points between a non critical chain and the critical chain protects the critical chain from variations in the duration of non critical activities The size of the feeding buffer equals to the half of the safety removed from the tasks that make that specific non critical chain As we are using aggressive but possible times we are not protected from variation in task duration Instead of putting safety buffer at each task using traditional time estimates we will put safety buffer at the end of each path At the end of the critical chain we ll put a project buffer It will protect the project duration from variations in the duration of critical activities The size of the project buffer equals to the half of the safety we took away from the critical activities We took away is 8 10 10 12 40 days so we ll set project buffer 40 2 20 days At the junction of each non critical path with the critical chain we ll put a feeding buffer The feeding buffer protect the critical chain from variations in non critical activities The size of the feeding buffer id determined in the same manner as the project buffer We have only 1 non critical path on this diagram We took away is 6 6 12 days from non critical activities so we ll set feeding buffer 12 2 6 days Step 4 Use buffer management buffer penetration to monitor project progress o Assume that project is now at end of day 15 but task Y has just been finished o Has any buffer time been consumed o


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