Código fuente laboratorio de modulación SSB-AM

Because of the reluctance of some managers to develop the logic diagram, it must be stated one more time that this is the most important part of CPM scheduling! The schedule dates, as you will see in the next chapters, are calculated from this logic diagram. If the logic diagram does not reflect the way the management team really intends on building the project, the dates, bar charts, and other reports created from it will all be incorrect. Updating the schedule

Conclusion

The careful development of the logic diagram is the most important step in the creation of a CPM schedule. The thought and time required to develop an accurate logic diagram will pay off later as the schedule is input into the computer and updated. A primary reason schedules are not used or are later abandoned is due to not tak- ing sufficient time to think through the logic and failing to obtain team input into the develop- ment of the logic diagram. Too many schedulers today overlook this important step. The first step in creating a logic diagram is to familiarize your- self with the project. Next, management team members and others involved with the project should be consulted and given an opportunity to give their input. With the overall goals in mind, the project must be broken down into activities. The work breakdown structure (WBS) is fre- quently used to help identify the activities before

developing the schedule. Once the management team is ready to create the hand-drawn network logic diagram, several methods can be used: the rubber stamp, mail labels, or sticky notes. The most critical aspect of the network logic diagram is that it accurately reflects the way management intends to build the project. The industry needs schedulers who understand the construction process—or at least obtain input from team members who do understand construction processes—rather than just computer operators who know the software and can make impres- sive-looking bar charts that have no technical merit. The thinking and development of the logic diagram is essential to succeed with the critical path method. This important step cannot be overlooked, nor can it be delegated to a per- son with good computer skills but poor con- struction and management skills.

Application

1. Create a logic diagram of the same project you created a bar chart for in Chapter 4. Do not look at the previous bar chart as you create this logic diagram. How does your thinking process compare with the think- ing process that went into the development of the bar chart? Write a short paragraph on the differences in the thinking process required to create a bar chart versus that required to create a logic diagram.

2. Which scheduling technique (the network or the bar chart) resulted in the most accu- rate and well-thought-out schedule?

3. If you are currently working on a project, create a logic diagram of that project covering the construction operations planned for the next few months. Then show that plan to other members of the management team and seek their input to revise and improve the plan.

4. From the logic diagram developed above, ask the two key questions of every activity and note the improvements they make to the logic diagram.

will be a time-consuming and confusing ordeal. The schedule reports will also be confusing, and everyone will hate the computer, the scheduler, and CPM scheduling in general.

To make sure the logic diagram represents the way the team desires to construct the project, double-check the diagram and ask yourself these two questions of each activity: (1) Does this activity really have to be done before each of the following activities can start? (2) What other activities need to be done before this activity can start? The above two ques- tions seem to be key to make the mind think of other relationships or activities that may have been forgotten in the development of the first logic diagram. It is important to take the time to double-check the network.

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INTRODUCTION

Now that the network logic diagram has been developed and the management team has thought through the project and developed a plan of exactly how they intend to construct the project as far as activities and relationships are concerned, it is time to add the duration to each activity. Most of the software has the ability to schedule by the hour or even by the minute. However, with construction applications, it is difficult to get a tradesperson to show up anytime during a single day to do a 20-minute job. Therefore, the durations typi- cally are rounded up to the next full day. If it is realistic to have one activity completed in the morning and another activity completed in the afternoon, it is still suggested that the project be scheduled by the day. Simply show the activities as concurrent in the network logic, with a duration of 1 day each. Then in the activity description, include A.M. or P.M. to

communicate the time of the day that activity should be done as shown in Figure 7.1 For some specific projects, such as in manufacturing or maintenance, it may be realistic to schedule by the hour, minute, or shift. The challenge is to make the durations realistic in practical real-world applications.

C H A P T E R 7