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Your Schedule Still Under A Risk.

Updated: Apr 26, 2021

Are you comfortable with all the estimations you made to your schedule?

Wait; still, one thing will change your mind.





I finalized my schedule as perfect as it can be, but interestingly I have noticed this case;

After 17 months from now, particularly on 31 January 2022 @ 08:00 AM, there will be 5 peoples, who I do not know, will report to the 10th floor of a building that does not exist now to install 10 lighting items that haven't fabricated yet by a supplier that is still unknown. Moreover, this activity is chained to the end of 36 correlated activities that most of them are facing the same situation of unknowns.

The above case is real, and does not reflect any defects in the developing of the schedules as much as it shows the uncertainty we offer to our construction programs in a situation where we have to confirm that they are 100% accurate & valid.


What is wrong about my plan?!

Probably you have done nothing wrong, but the way we develop our detailed schedules and the construction project's plans is not adequate to absorb the fluctuation nature of the construction process. there are many factors and actions shall be done to support the start and the end of each task such as;

  • Making the construction drawings ready and approved.

  • Delivering the material to the site.

  • Completing the predecessor activities on time.

  • keeping the productivity rate of labors as planned.

  • others

There are many, and each factor may hold sub-factors and concerns that definitely will impact the accuracy of the completions dates of the different tasks. However, I may address one factor to show how far these factors could impact the schedule accuracy.


keeping the productivity rate of labors as planned.

The schedule total duration comes from the accumulation of the activities' duration which depends on the analysis of the quantities of work against the productivity rate (man-hours), then you drive the man-hours calculation to get the total number of workers/day. hence, the productivity rate is based essentially on human efforts. The question is; how far can you guarantee an accurate productivity rate from a human?


What should 1% drop in productivity do to the schedule?

1% drop in productivity rate tends to be less than anyone can realize, but if it happens, the schedule may show a total delay of (5) days to the critical path as shown in the above schedule as an example. The 1% drop may come from losing only (5) minutes/day from the net time which labors should consume to do the work. See, only (5) minutes drop each day can result in losing the project completion date and put the contractor and a delayed penalty which may lead him to lose his profit of the project. 5 minutes are easy to be lost in a side chatting between the crew members, small break to drink water, smoking, search for a missed tool, or any regular human behavior during the work time or simply comes because one of the labor does not physically fit 100% to commit the productivity rate in a certain day.


How about losing 5% or 10% of the net time to do the work in the critical path?

  • 5% equal to 25 Minuets/day will impact by (23) days delay

  • 10% equal to 50 minuets/day will impact by (46) days delay

This is the output of our detailed schedule, minor events make a significant impact. I am not talking about wasting time during the engineer's instruction or the time allocated for the normal break in the mid of the day, because these times should be calculated within the productivity rate, but I am concerning the net time for the actual work to be done.

50 minutes are not hard to lose. it is normal to encounter several days when some of the labors were delayed to report to the site for any reasons, a piece of equipment has run out of use, or some other minor events that might not be significant to the project manager's concern.


This is not the whole fact.

Planners who love detailed schedule may suggest to put a margin for such risk, but still you will face a problem of accuracy to the project total budget cost. Additionally, they will be challenged by the other factors which I mentioned above to let those 5 people to come in 31 January, 2022 @ 08:00 AM to install the lighting fixture as planned.


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