Activity Relationship

Redundant logic is where you can remove a link with no effect on the schedule.  In your situation, one of the two links controls the calculation (probably the finish to start) the other is redundant.  This is different to having two links that serve different purposes - typically a Start-Start and a Finish-Finish, this arrangement is called a 'ladder'.  For more on this see: http://www.mosaicprojects.com.au/PDF/Links_Lags_Ladders.pdf

Hello,

i'am still getting difficulties in calculating ES,EF,LS,AND LF.please advice

Rafael,

we usually model such situation applying partial workload.

If to assign resource crew on activity B with 40% workload its duration will be 7.5 days and all restrictions will be met.

From: Links, Lags and Ladders

http://www.mosaicprojects.com.au/PDF/Links_Lags_Ladders.pdf

- “When using ‘Hammocks’ it is important to ensure that the Hammock does not become a controlling link in the schedule – the activities ‘under’ the Hammock should be logically linked from end-to-end.”

I do not believe the above statement is correct. Hammocks are defined by certain points but there are no activities under hammocks. Hammock may link two points on activities or milestones not linked with any other activity.

The statement that the scenario in figure 12 represent the optimum situation is wrong, in most situations like in construction activities splitting the activity is not always desirable.  During the course of a job any activity can become critical or stop being critical, if the activity is not critical it makes no sense at all to split it.  Also some activities shall never be intermittent no matter if critical. How intermittent is a function of each individual activity. 

Some software promotes such bad practice across the board, others [believe Asta PP] at the individual activity level.  I do not mean it cannot be improved but at the moment I have not seen an acceptable application that gives the user a reliable outcome.  Until substantially impoved the application of automatic lag drag removal for this particular case shall only be used for a convenient what-if check, I do not oppose to its existence but to how it is recommended to be used.

Activity splitting is not a sin, in some cases desirable, the how can be.

:)

Vladimir,

I like your approach for most of situations of continuous feed in Construction Schedules but at times I would balance the continuous feed by adjusting the production rates, such would be the case of a factory production line, in some cases adjustment on both, workload and production rates can be a better choice.

Not always a fully automatic approach is better, in such cases the above calculator helps a lot.

For the general case of lag drag it might be better to use other resource assignment, perhaps using team/resources fixed hours and use of dynamic skill replacement. 

I believe on the end it is a management decision how to fix it, therefore I accept it as "usually" and not a fixed rule to be programmed into the software. I see as the case of out-of-sequence progress where none of the temporary fixes always represent a best choice.

BTW my definition of the general case of lag drag does not depends on SS & FF links between same activity, this shall also be solved case by case using management decisions. With help of Start Flex I can figure out where is lag drag happening an make the decision, which usually is keep the lag drag as it is not always critical.

Best Regards.

Rafael