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The expected project completion time t p - sum of the expected times of all the activities on the critical path. The project variance PERT uses variance of critical path activities to help determine variance of the project. Project variance is computed by summing variances of critical activities: Project variance = Σ (variances of activities on critical path) Variance of critical activities are: A …
Jul 15, 2015 · Expected completion of a PERT project is the sum of the expected times for individual activities that are on the critical path. (Determining the project schedule, moderate) The expected completion time of a project activity uses the Beta distribution ; expected time is the weighted average of optimistic , most likely , and pessimistic time estimates .
Sep 10, 2014 · Here is a CPM network with activity times in weeks: a. Determine the critical path. There are three paths here: 1. A-B-C-D = 7+5+6+6 = 24 weeks 2. A-E-G-C-D = 7+4+3+6+6= 26 weeks 3. A-E-F-D = 7+4+8+6 = 25 weeks Since the critical path is the path where the sum of the activity times is the longest (p.348), the longest path would be the middle path, A-E-G-C-D.
Sep 01, 2021 · LST − EST LST − LFT Free slack time is associated with a _____ activity. critical noncritical lone redundant Activities in a _____ path share slack time. sequential disjointed broken fragmented Given the project network for: Activity EST EFT LST LFT A 2 2 B 2 3 3 4 C 2 4 2 4 D 4 7 4 7 The completion time for this project is _____ weeks. 8 0 ...
The company creates the project schedule by assigning each task to a specific employee. Each task includes a deadline that must be met in order for the next task to begin. Each employee maintains responsibility for managing the task assigned to him and ensuring that it is finished by the deadline. The employee can enlist the assistance of others, but ultimately he is accountable. Employees who are assigned tasks on the critical path face higher scrutiny due to the importance of these tasks.
Company employees need to complete each task on the critical path by the deadline in order to maintain the project schedule. Tasks along the critical path determine the deadlines required. The deadlines assigned to critical path tasks must coordinate to facilitate completion of the final project on time. After assigning these deadlines, the company ...
Creating the critical path involves identifying all of the tasks necessary to complete the project and determining which tasks control the completion of the project. The company creates the critical path by detailing each task required and identifying which ones rely on the completion of other tasks. For example, when baking a cake, the chef needs to bake the batter before applying frosting. The critical path consists of the series of tasks that take the longest to complete, and thus sets the maximum length of time required to complete the project.
Let us take a simpler example than John’s home construction example we saw in previous lessons.
Activities for this project are as below (output from Define Activities process) –
Sequence activities and build schedule network diagram (output from Sequence Activities process) . This is how it looks, with individual activity duration in minutes –
The importance of calculating Total Float and Free Float are found it the definitions of these terms. As stated earlier, float values indicate how much each individual activity can be delayed before affecting successor activities or the planned project completion date. The float calculations for the sample schedule are shown in Exhibit 5. Formulas for calculating Total Float and Free Float are as follows: 1 Total Float = LS – ES (it is also calculated by LF – EF) 2 Free Float = Lowest ES of successors – EF
Critical Path Method (CPM) schedules have evolved into valuable management and communication tools for today’s complex projects. Activity-on-Node (AON) schedules show the Critical Path of the schedule, and thus are considered to be CPM Schedules. It is through these schedules that the logical flow of the work sequence is graphically illustrated. In addition, schedules also show the planned start/finish dates for activities, schedule duration, and float values for the individual activities on the project. One should note that schedules could also be structured to show other types of information such as budgeted costs or labor quantities. However, these options are not addressed in the basic scheduling discussion of this paper.
Once the float values are calculated, the string of critical activities will be identified. This continuous string of critical activities is called the Critical Path. Critical activities are those that do not posses any float. Note that the summation of the critical activity durations (Activities A, B, D, and F in Exhibit 5) is equal to the overall project duration (which was calculated in the forward pass). This reinforces the fact that a delay (or additional time added to the activity duration) in any critical activity will cause a subsequent delay in the completion date. While it doesn’t appear in the example problem, a schedule can have more than one branch or string of activities that make up the critical path. See Exhibit 6 for an example of a computer-generated CPM schedule.
The second step in the calculation is comprised of the Backward Pass. Through this pass, the Late Start and Late Finish values are calculated. The formulas for the backward pass are shown below:
Schedules are used as management tools to communicate work sequence, dictate start/finish dates for activities, and to track progress on just about every type of project. In today’s business world of complex projects, managers can get lost in the plethora of information provided by the project schedule.
A common way to express the sequence, or logical order, of the activities is through the means of a logic diagram. In a logic diagram, “nodes” (squares or rectangles) represent each activity with arrows representing the relationships between these activities.
First, an activity’s value for Total Float can either be greater or equal to Free Float. Or in other words, Free Float can never be larger than its value for Total Float. Second, the Critical Path must be continuous from the first activity in the schedule all the way through to the last activity.