Roger:

One example of using a SF relationship:

Let us think of a one story rectangular industrial building. Different discipline or trade work is hanging from the roof structure, like main electrical distribution, lighting, HVAC, compressed air, etc. The advance of work is lengthwise, for example from East to West. Some trade work need to be installed before others, for example A before B. Let us also assume that A and B do not span the whole length of the building, but they overlap at the middle of the building. Let us assume also that your schedule is not a detailed schedule so you have one activity per trade for the whole roof. B goes from the East to the middle and A goes from the middle to the west of the building. You can start A and B any time independent from each other, but you cannot finish B until you start A and do some work in the middle of the building. Therefore, you need a SF relationship from A to B with a lag.

You need to use many SS and FF relationships, and some SF relationships, when you develop a high level schedule like when you need one for bidding a job.

One more example of a SF relationship:

In a commercial building let us say that activity A is a main electrical feeder that comes hung from the roof inside the ceiling and feeds a distribution panel or load center supported on a light weight steel stud partition. You also have activity B for the erection of partitions for that building section. You can start both activities any time independent from each other, but you need some work (and not all) done on the partitions to finish your feeder. Therefore you need a SF relationship from B to A with a lag.

Tomas Rivera
Altek System
Detailed scheduling of high
performance construction projects

Andrew:

It would be great to have the option of "scheduling durations as interruptible" to apply it to only selected activities.

Also, you are right that this option applied to the whole project is useless for most real scenarios. Even so, it has been very useful to me in some real scenarios (not most though). I have used it several times in real scenarios getting reductions in the project duration. Let me explain.

Some times you have activities linked with SF or FF relationships. Therefore, you might end up with activities which have predecessors to their finish nodes and successors to their start node in the same activity. If it happens that one of these activities is in the critical path, your project finish date would be earlier if the duration of this activity is increased. Or the other option, is to allow the activity to split by means of the function "scheduling durations as interruptible".

Also, not only you can benefit from earlier project finish dates; but also from increased project float when having this type of activities not in the critical path.

Tomas Rivera
Altek System
Detailed scheduling for high performance
construction projects

Alternatively, define a global change to impose early start constraints. However, what you then have is a picture, not a plan !.

Hi there, I tried the way that mktse says. By importing my new EF and ES from Excel to P3 it doesn’t produce any constraint on related activities; therefore when I schedule it by F9, again dates will change again. Is there any sort of import rule that I can tell P3 import my dates as constraint or expected finish?

Tomas,
I’m a new member. I was going through new/old posts and came across your offered solution to Madahav’s query. Unfortunately the option of "schedule durations as interruptible" is not available in P3 e/c. I just wonder why such a fantastic option was missed out in P3 e/c.It may not sound to be a good option to some, but it surely allows to stretch an activity more than it’s original duration, as driven by it’s predecessor’s FF relaionship. I’ve trying hard to find an alternate to "interruptible" within P3 e/c. Would appreciate if somebody could suggest a solution.

Madhav:

There is another way you can try, although it will not give you everything you want.

If you set up your activities as you said and give activity 2 a duration say of 1 day, then when you schedule your project you can select in options "schedule durations as interruptible". This way your start and finish dates of both activities will be the same, but your duration for activity 2 will stay in 1 day. Also when you display or print a bar chart activity 2 will show one continuous bar from the start date to the finish date. This will treat the rest of your project the same way, and might change other activities dates and your project finish date.

Tomas Rivera
Altek System
Detailed scheduling and control of
high performance construction projects

I mean if the link remain duration and schedule percentage is flagged on.

Also if I do not like this option.

Steven,
You can not update an hammock independently from its under-laying activities. Here the last statement of my post “You may have a problem with this solution if the Act2 progress is independent from Act1.”

Can you progress a hammock independantly of its underlying tasks ?

Could try setting the expected finish constraint = ef as a Global Change