In the previous chapter we have seen what could be the possible impact on the activities linked with either ‘Start to Start’ or ‘Finish to Finish’ links after updates on predecessors.
You must have also noted that in case of ‘Start to Start’ link if the predecessors are delayed then the impact is not shown on the activity and its successors, which is extremely risky.
Similarly in case of ‘Finish to Finish’ link if the predecessor is delayed in start but finishes on time the technical condition for starting may not be met with. However it is not as risky as the ‘Start to Start’ link case.
Now I am check the same schedule with ‘Finish to Start’ links.
With ‘Finish to Start’ link; to match the technical conditions at both the start and end, I am considering that the Plastering starts after finishing block masonry but with a lead of 6 days. Similarly the Painting starts after finishing plastering but with a lead of 6 days.
Choosing this particular lead has a reason with some calculations that the Plastering will start after 12 days of start of Masonry to allow 5 days for completion of at-least a wall and then 7 days of curing. Note that the duration of plastering is such that it ends after 10 days of completion of Block Masonry and again allows for 7 days of curing for last of the walls and 3 days of duration for the plastering work of the last wall. You can check the same happens with Painting where at both start and end the curing period is allowed and at beginning 3 days for plastering of at-least a wall is allowed at and end, 5 days for Painting of last wall is allowed.
The Schedule with ‘Finish to Start’ links with leads, looks like this:
The schedule is looking exactly the same as with ‘Start to Start’ link or ‘Finish to Finish’ link. However let’s check how it behaves in various conditions after updating it.
- If Start of Activity 01 – Block Masonry Flat 101 is delayed by 3 days
The entire schedule is shifted by 3 days as shown below:
This is again the same as in ‘Start to Start’ Link and ‘Finish to Finish’ Link. The start and end Technical Conditions are met-with.
- If Activity 01 – Block Masonry, starts on time but the End is delayed by 3 days
This looks same as the Schedule with ‘Finish to Finish’ link after update. As you can notice the technical conditions at end are met with. Although activity 02 – Painting Flat 101, can start earlier because of the technical condition at start but the update is showing it as starting 3 days late, however this is not a major concern.
- If Activity 01 – Block Masonry, starts late by 3 days but the is completed on original date
This again looks similar to the updated schedule with ‘Finish to Finish’ link. Again in this update the technical conditions at start are not meeting but technical conditions at end are met-with.
The Activity of {Plastering and Painting actually cannot start as shown on the updated schedule.
Despite such faults after update for schedules with ‘Finish to Finish’ or ‘Finish to Start’ links, just think about the risks involved with the schedule with ‘Start to Start’ links. With technical conditions being met for the end dates there is always a possibility to still complete the works in time by augmenting additional resources, however if the technical conditions are not meeting the additional resources would be useless. Naturally the risk is higher in schedules with ‘Start to Start’ links.
Think about the possibility of such an even happening where the activity with a delayed start is completed on original time; it’s very limited. Also think about how the activity which got delayed at start, did finish on time. This would not be possible unless one deploys additional resources and if such attention is paid to the updates on schedule then naturally one would see the risks associated with successors and would be keen to deploy additional resources to be on the track again. However, it would be done only of technical conditions are met-with, which was the case in schedules with ‘Finish to Finish’ and ‘Finish to Start’ links but not in case with ‘Start to Start’ link, where technical conditions would not allow deployment of additional resources.
Thus the schedule with ‘Finish to Start’ & ‘Finish to Finish’ links are preferable and Schedule with ‘Start to Start’ links should be avoided.
Happy Planning!
ADGP www.decodingcm.com https://decodingcm.blogspot.com