DOC PREVIEW
MSU ECE 480 - ganttv1

This preview shows page 1-2 out of 6 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Graphical Project Planning Techniques: An Overview of Gantt, PERT, and CPM Charts Prepared for groups in ECE480 1/6/02, D. Grover Introduction/Purpose The purpose of this brief tutorial is to present an overview of several graphical project planning techniques and provide a “cookbook” approach to creating these charts for a project like those encountered in ECE480. This should not be taken as a definitive study of the Gantt, PERT, or CPM charts, but should be helpful for those students unfamiliar with these techniques. Background Projects that involve more than one person and/or more than one step pose the following questions: • What tasks need to be done to complete the project? • When and in what order will these tasks be done? • Who will do each task? • What are the intermediate deadlines (e.g., status reports), and what will be done by these deadlines? To answer these questions, additional issues arise, such as: • How long will each task take? • What dependencies exist between tasks? • Who has the knowledge/skill/time to do each task? • What external constraints exist (e.g., time to order parts)? The Gantt, PERT, and CPM charts describe the answers to these questions in time-oriented diagrams. In all cases, the “task” is the basic unit of interest. In this context, a task is some significant activity the group will need to perform to accomplish its goals. Note that the group will have goals that include the project itself as well as presentations, reports, proposals, etc. Tasks are given: • a name/description (typically, verb-noun, as in “design control board” or “research literature”) • an estimate of the amount of calendar time required • a list of other tasks (if any) that must be completed before this task can begin (or end)—i.e., dependencies.Other task attributes can be added if desired, such as time required in person-hours and other resources required (e.g., financial, special skills, special equipment). Besides tasks, other information is required, such as: • the overall project start/end dates • other deadlines or milestones (e.g., reports, etc.) • factors affecting time available (e.g., holidays, breaks, other classes, presentations, etc.) Now the three methods (Gantt, PERT, CPM) will be described. Following that, a “cookbook” approach to the creation of a Gantt chart will be presented. Gantt The Gantt chart was invented in the early 1900’s by Henry L. Gantt, an American engineer and social scientist. The horizontal axis is (linear) time; each task is given its own horizontal band where the calendar duration of the task is indicated by a box, line, or other object with a variable horizontal dimension. Tasks are often grouped into categories, and each category can be treated as a summary task whose duration spans all the tasks within that category. Figure 1: Example Gantt chart, generated using Microsoft Project (source: http://www.me.umn.edu/courses/me4054/assignments/gantt.html) Tasks are generally listed from top to bottom in the order they will occur; if there are groups of tasks, the tasks are chronological (by starting date) within a group, and the groups ordered by starting date.The horizontal axis has a resolution appropriate to the type of tasks; a resolution of one day is useful for most projects. Note that if significant work is not expected to be done on weekends, these should be omitted from the chart, otherwise tasks will have their durations distorted if they straddle days when no work is likely. A vertical line is usually placed on the chart to show the current date. Other important milestones can be noted (and labeled) with dotted vertical lines at the appropriate dates. The advantages of the Gantt chart are • time is explicit (and linear) • all tasks visible in relationship to others • deadlines are shown • project status at intermediate times is shown • can show progress by “filling in” task boxes The unmodified Gantt chart has the following shortcomings: • tasks might not be associated with people (solution: tag tasks with the initials of the people responsible) • person-hours are not indicated, only calendar time (solution: note person-hours near the task “box”) • dependencies are not explicit (solution: imply dependencies by ordering tasks, or use extra lines and arrows) • no summary of the load on a person (solution: create an additional set of horizontal “task” lines for each person, showing what tasks they are working on when) • other resources not shown (e.g., financial) (solution: note resources in description or near task “box”) • critical paths are not explicit (solution: use highlighting or other graphical means to indicate the sequence of tasks along the critical path) • does not record difference between original plan and actual (solution: enhance the task “box” to show two different durations—an upper (actual) and lower (estimated)) PERT A few of the shortcomings of the Gantt chart are solved in the PERT chart (Program Evaluation and Review Technique”). (See Figure 2.) The PERT chart uses a connected series of nodes to make explicit dependencies between tasks. In addition, the order of tasks is given by the flow of the connections left to right, but the horizontal axis is not necessarily linear in time.Figure 2: CPM (PERT) chart. Nodes are events (here numbered 1-8), which occur on completion of tasks. Lines connecting events are tasks (activities), which have a calendar duration (in days) noted. The bold lines show the critical path. (Source: http://www.doc.mmu.ac.uk/online/SAD/T04/projman.htm) The PERT chart can be more compact than the Gantt, but does so at the cost of a linear time scale. The time resources required by a task are given numerically, rather than appearing graphically (i.e., horizontal dimension) as in the Gantt chart; this may make it harder to quickly see what areas are using the most time resources. CPM The CPM (Critical Path Management) chart is similar to the PERT chart but includes an explicit indication of the “critical path”—that sequence of tasks that defines the minimum amount of time for the project. Put another way, these are the tasks that a delay within will delay the entire project. One or more sequences of such tasks always exists; the CPM chart makes these paths (usually just one) explicit. Otherwise, CPM


View Full Document

MSU ECE 480 - ganttv1

Documents in this Course
sd97

sd97

17 pages

ap_EO

ap_EO

14 pages

Load more
Download ganttv1
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view ganttv1 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view ganttv1 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?