Because additional resources are being added the

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Because additional resources are being added, the crash cost logically would be higher than the standard cost. Shortening Activities It is not realistic that every activity can be shortened, but some activities can be. The length of time that an activity can be shortened is the difference between the standard and crash times. The goal of the project manager is to shorten the activity as much as possible, but to keep the crash cost as minimal as possible. When deciding which activities to shorten, the project manager must consider if the amount of time an activity is crashed is permissible, the reduced time will complete the project by the due date, and the total cost of crashing is minimal. Calculating the Project Crashing There are four steps to calculating the project crashing: Step 1: Step 2: Identify the critical activities and critical path(s) in the project network. Step 3: For a single critical path, select the critical activity such that each selected activity can be crashed and the total crash cost per period of all selected activities is the smallest. Step 4: Update all activity times. If the desired due date has been reached, stop. If not, return to step 2. Example Project For the example project, the crash cost per week has been calculated for each activity in the following table, using the crash cost per period formula in step 1. The client has requested the project a week earlier, so the duration of the project must be reduced by 1 week to meet the desired due date. Current Critical Path The current critical path for the example project is Start-A-C-E. Recall Start is a dummy activity. Looking at the crash cost per week for each of the critical activities, A is $1, 500, C is $3,000, and E is $500. Activity E has the lowest crash cost per week at $500. Activity E has a crash time and is the cheapest, so activity E should be reduced by the week. Activity E reached its crash limit of 1 week and cannot be crashed any further. The path Start-A-C-E remains critical as the longest path in the project network. The completion time was reduced by 1 week with the crash of activity E. The completion time reduced to 8 weeks (3 + 4 + 1). The completion time of the other paths in the project network must be checked to see if any other critical paths were formed with the crash of the activity. For this project, the only critical path remains as Start-A-C-E.
Further Crashing If other critical paths were formed, any further crashing would have to be done to all paths. Crashing activities common to more than one critical path may be cheapest. However, the crash costs should be compared. Now, in step 4, the activity time for activity E was updated. Crashing was done with the desired reduction of 1 week being met. If the desired due date was less than 8 weeks, then another activity would have to be crashed. The cost of the additional resources was $500.

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