We are confronted with having to reduce the scheduled complete time of a project to meet a deadline. The project duration can be reduced by applying more resources like more labor, additional equipment, and working overtime hours to complete the project.
After observing the MSP timeline, we selected the most critical tasks for the project:
Framing 14-16 Floors Steel Framing
Concrete Flooring 7-16
Rough-Ins
Utilities
Finishes
Furnishings
Closing
In considering the “crashing” method, hypothetical we are trying to reduce the duration by half of the time for each task. To demonstrate the procedure, we will focus on the concrete flooring 7-16; since it has the longest duration out of the other tasks.
Concrete flooring 7th to 16th floor, the normal cost which is $1,900,000.00 with duration of 315, which is our normal point. Since we are assuming that we’re reducing the duration by half, we can divide the duration by 2; 315/2 = 157.5(Crash time). Also the normal cost will be multiply by 2; ($1,900,000.00*2) = $3,800.000.00(Crash cost).
Calculating the Cost slope:
Cost slope = (Crash cost – Normal Cost) / (Normal time – Crash Time) = ($3,800,000.00 - $1,900,000.00) / (315 – 157.5) = $1,900,000.00 / 157.5 = $12,063.49 per unit of time
Now that we have the values for the crash cost and crash time, we can construct an activity graph. See graph below.
Even though the Concrete Flooding 7-16 has the longest duration, it’s not the task with the steepest slope from the rest of the tasks. The steepest slope is Furnishing. It will take $154,451.39 per unit of time, which means this task will cost the most to shorten the duration on the project. See the table below.
The following are the most critical task for the project. The table shows the slopes for all of these tasks.
Reduce Duration by Half on Project
Direct Costs
Normal
Crash
Slope
Max Crash Time
Time
Cost
Time
Cost