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Regarding predessors & Sucessors

5 replies [Last post]
sai krishna raju
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the client wrote there are many activities thathave only ss succesors(s).this is not good scheduling practice and should preferably be avoided.
Is there any criteria that we want to use FS,FF,SS or SF in these we have to use fs more?

Replies

sai krishna raju
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Thanks all of you 

Zoltan Palffy
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not only does the GSA use a 90% threshold but the DCMA 14 point schedule asessemtn also states that 90% of the activity relationship types should be of the FS type. That means that there can be 10% of the SS or FF relationship.

Techanically using only a ss will flag the activity has not having a successor. What you can do is create a compound or combination relationship. On the activities where you know only have a SS successor and add successor of the same activity id but with a FF relationship. The SS successor will tie down the start of the activity while the FF successor will tie donw the end of the activity.

Zoltan Palffy
User offline. Last seen 19 hours 6 min ago. Offline
Joined: 13 Jul 2009
Posts: 2327
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not only does the GSA use a 90% threshold but the DCMA 14 point schedule asessemtn also states that 90% of the activity relationship types should be of the FS type. That means that there can be 10% of the SS or FF relationship.

Techanically using only a ss will flag the activity has not having a successor. What you can do is create a compound or combination relationship. On the activities where you know only have a SS successor and add successor of the same activity id but with a FF relationship. The SS successor will tie down the start of the activity while the FF successor will tie donw the end of the activity.

As per GAO most of the relationships in  a detailed schedule should be  Finsh to Start. Generally  more than 90% activites with FS relationship without any lag is preferable. Other relationships SS and FF also can be used for paralel works without any dangling logic ( Open ends ). 

Santosh Bhat
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The problem with using too many SS linkes as successors is that any delay to the firsty activity, will not lead to a delay in the second activity, and so on throughout the whole network.

FS links are the ideal relationships as they will have a consequential affect upon subsequent activities due to delays, or duration elongations earlier in the network. However, SS & FF links are equally valid if there is a degree of parallelism between activities.

As SS successors are effectively open-ends, it's good practice to also include a corresponding FF successor for every SS successor.