Defining Activity Relationships in Primavera P6 EPPM
Figure 1 illustrates how P6's Retained Logic and Progress Override options deal with respects or “retains” the logic relationship between the finish of Activity B and resumption of progress on Activity C, which means that Activity C Activity C to begin as early as possible, which in this simple example is on the data date. Oracle Primavera P6 Data Dictionary Baseline Data Date. The late finish date for imported activities with external relationships to. If you are not familiar with the process of defining relationships between activities in Primavera P6 Enterprise Project Portfolio Management.
B must continue as long as A has not started. It is not necessary that B finish once A starts, but it is allowed to finish once A starts. Making such a link between these two example activities is easy enough.
Start to Finish Relationships - to use them, or not?
And indeed here it is, as performed in Primavera P6 Professional. The following figure shows the Start to Finish link on the A and B example. I think further confusion comes when thinking about SF linked activities in context with other preceding or succeeding activities.
It can be hard to grasp what a Start to Finish link is buying us in terms of how the critical path will be affected and how these predecessors and successors will be impacted. And my research uncovered no practical discussions of SF relationships in the context of a true scheduling situation. For now, both the activities are sitting back on the Data Date because they have no other predecessors. Nothing has been moved when the schedule was calculated because activity A is not dependent on the longer duration activity B.
In order to power up the lines, there must be some effort to get the cable run from the power grid to the site.
So this would precede the Turn on Power Line to Site activity. Now what do we have? The Start to Finish relationship is pulling on its predecessor. What is also interesting is that if you look at the Total Float value for the Run Generator activity, it only shows 2 days. Why only two days? To answer that question we have to go under the hood and look at a sample of the forward and backward pass process on our Start to Finish activity.
Now you might be wondering why B is apparently showing a 2 day float on the late dates, but a 3 day float on the early dates the delta between the early and late dates is the total float. If activity is turned off any later than that, it will in this example become critical. The float of activity B then, is always equal to the duration of its SF predecessor A. Moving on… Ok, pass the Excedrin and enough of this backward number-crunching stuff. It just makes me glad I was borne in the computer age.
How Retained Logic, Actual Dates, And Progress Override Deal With Out-Of-Sequence Progress
Imagine doing this stuff manually like they did in the project rooms of yesteryear. Indeed I wonder if they used SF at all. All we need to know these days is that Primavera P6 is doing it right. So what has all this bought us in terms of our power lines and generator scenario?TT P6001 Removing P6 Relationships By The Masses
An example from the research industry is that documentation cannot complete until experimental testing described by that documentation has finished. In this not so common relationship one activity cannot finish until another activity has begun.
An example is the run generator activity cannot cease until the activate power activity is complete. Lags and Leads Lags and leads also have a significant impact on the length of the schedule. A lag describes a required time between activities.
In the FS relationship this means that the second activity cannot commence until a scheduled period of time has elapsed after the completion of the first activity.
The most common example is concrete, in which a lag is inserted between activities to allow the concrete time to cure before the successor activity can proceed. A lead has the opposite effect on the schedule.
Start to Finish Relationships – to use them, or not?
A lead is the amount of time that a activity can start before the completion of the first activity. Many schedulers refer to lead as a negative lag. Note that the use of leads is discouraged by scheduling guidelines. Relationships Tab To add a relationships tab to the activities page view first click on any activity to invoke the Activity Details tabs at the bottom of the page. Right-click on any of the tabs in the bottom layout area. Select Relationships from the corresponding menu, Figure 2.
Highlight Notice to Proceed then select the Relationship tab. In the corresponding Successors dialog area select add successor icon, Figure 3. Figure 4 Project Start will appear in the Successor dialog area.
We first highlight all the activities as displayed in Figure 8. Figure 8 Right-click on any of these selected activities and choose Link Selected Activities from the following menu, Figure 8. This assigns a Finish-to-Start relationship between all these activities.
Assigning Concrete Cure Time Lag Now we want to assign a lag between Pour Concrete and Strike Forms to give the concrete thrust block time to cure before we remove the forms.
- Defining Activity Relationships in Primavera P6 EPPM
- Time-saving Tricks in P6 You Must Use
- Start-to-Start relationship, predecessor stops enforcing successor start date
To set the lag to a hours per day lag select the Schedule icon, Options button in the Schedule Project dialog, and 24 Hour Calendar for the Calendar for scheduling Relationship Lag option in the Scheduling options dialog, Figure 9. Figure 9 Now it works best in Primavera P6 if you enter the cure time lag in hours instead of days, and let P6 compute the equivalent time in days.
So one hour cure time period will be 3-days cure time lag. A 5-day cure time or hours computes to a day cure time lag.