Critical Path Methode (Cpm)

Introduction

There are projects going on all around us everyday. Some are large and some are small. Projects are unique, it is one time operation designed to accomplish a set of objectives in a limited time frame. Example of projects includes designing new products or services, construction of shopping mall, merging two companies and designing and running a political campaign. They all involves tremendous amount of planning, preparation, and co-coordinating work that needs to be done. Projects may involve considerable costs. Some have a long time horizon, and some involves a large number of activities that must be carefully planned and coordinated. To accomplish this, goal must be established and priorities set. Task must be identified and time estimate made. Resource requirement must be projected and budget prepared. Progress must be monitored to assure that project goal and objective will be achieved.

In our case, we have building construction project. A farm owner is going to erect a maintenance building with a connecting electrical generator and water tank. The activities, activity descriptions, and estimated durations are given in the following table:

Activity Description Activity Predecessor Duration

A Excavate None 2

B Erect building A 6

C Install generator A 5

D Install tank A 4

E Install maintenance Equipment B 4

F Connect generator and tank to building B, C, D 5

G Paint prep B 3

H Paint finish G 3

I Check out facility E, F 2

The building should be completed in no more than 16 weeks. He wonders what the probability of completing the project in that time is.

Before we start our analysis using certain tools, I will define some terms regarding the project.

Definition

Project management: a team-based approach for managing project.

Nodes: junction points where arcs meets.

Arc: connects two nodes, precedence relation.

Critical: an activity or event that, if delayed, will delay some other important

event, such as the completion of project or a major milestone.

CPM (critical path method): tool for planning and coordinating large project.

Path: sequence of activities that leads from the starting to the ending nodes.

Critical path: the longest path, determines expected project durations.

Network diagram: diagram of project activities that shows sequential relationship

by use of arrows(arc) and nodes.

Slack: allowable slippage for a path, the difference between the lengths of a path

and the length of the critical path.

ES: the earliest time activity can start.

EF: the earliest time the activity can finish.

LS: the latest time the activity can start and not delay the project.

LF: the latest time the activity