Scheduling for Estimators

Logical Connections and Lag

With the listing and sequencing completed, it is time to enter this information into a scheduling software program. There are three basic connection types that you must chose from when assigning logical connections. The three connection types are:

• Finish to start (the preceding activity must be finished before the current activity starts)
  
• Finish to finish, (the current activity’s finish depends on the preceding activity’s finish)
  
• Start to start, (the current activity start depends on the preceding activity’s start)

Lag is a way to add an important twist to these logical connections. You may determine that the current activity should start one week after the preceding activity starts. In that case, the logical connection is start to start with one week of lag. The same concept can be applied to all three logical connection types.

After the information is entered and the logical connections are made, assign a duration to each activity. Your fist pass through the schedule should include normal activity durations even if you know that the project must be accelerated. This will give you a look at what the normal duration of the project should be. You can then go back and accelerate critical activities to obtain the required project duration.

This process will allow you to identify the specific activities in your project that require special handling and probably, increased cost. As an estimator, you are well aware that accelerated activities will probably cost more than the same activity performed in a normal duration. Choosing the acceleration method of individual activities is an important estimating function.

The estimator can often chose between using overtime, extra shifts, stacking trades, or even adding resources to the project to obtain the necessary acceleration. There is a different cost associated with each acceleration method.

You now have the first draft of your critical path schedule completed. More than likely, you will have to review everything to determine that your work has created a comprehensive and accurate preliminary schedule. Adjustments can be made at this time so that the schedule truly reflects the estimators concept for project execution.

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Introduction

Bar Charts are not adequate

Preliminary critical path schedules

The scheduling process

Procedure for a sample project

Summary

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