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Double Links

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Rafael Davila
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Vladimir.

While investigating some formulas to get Relationship Float [SLACK], Double Link Remaining and Elapsed Lag1 and Lag 2 values and other relationship values I found it might be convenient to show both lags as well as their calendars in the Succeeding Activities column.

http://www.austprojplan.com.au/relationship-float-and-viewing-in-primave...

Needless to say I am starting with time lags only, volume lag will follow and then some Double Link parameters.

Best Regards

Rafael

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Rafael Davila
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I am trying to figure out how to calculate finish dates for volume lag without having to mimic volume lag as an activity of production type. 

  • It looks like not all lag can be modeled as an activity, in particular volume lag.

In the following scenario I opened some SS and FF slack by delaying Cement Plaster using a date constraint.

End of Volume Lag

Multiple resources working on different shifts, variable quantity and partial workloads can complicate the calculations that anyway were done during the schedule run.  In order to better understand current status and the schedule behavior these values are needed. 

Double lags I rarely use but volume lag I use more frequently.

Any help will be welcomed.

Best Regards,

Rafael

Rafael Davila
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EXCELLENT!

Add_Hours_Calen

Easy and fast, works with fractional numbers. From now on exploring uncommon float values will be easy.  I was needing such a function for some backward computations to get relationship float for double links.

GIF-ThankYou

Rafael

Rafael Davila
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Vladimir,

Basic Scripts to increase D1 by work hours done: 1st version missing ability for unit in days.  I used an iteration method as considering calendar week and exceptions by other means can be difficult.

Increase Date by Work Calendar2

N can be negative.

Decrease D1

  • A huge limitation of this approach is that the script can only be applied to a single date field.
  • Another limitation is that N shall be an integer.  Maybe some sort of data validation for numeric fields could be implementd to limit values to be fractional/integer and to be within certain values range.
  • A Spider Function is better for this purpose.

Best Regards,
Rafael

Marcus Possi
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As always, Spider Project Team Surpassing expectations, better... Making them available.
Rafael Davila
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Excellent!

I already copied your last posting into a PDF for future reference, so good I suggest publishing it at Spider website and keeping it updated as need be.

Spider - Start, Finish and Float Fields

Best Regards,

Rafael

Spider Start, Finish and Float Fields

Early Start and Early Finish show the dates calculated using CPM ignoring resource constraints.

Start ASAP and Finish ASAP show early dates in the current schedule calculated considering all project constraints (resources, supplies, financing).

Start ALAP and Finish ALAP show late dates in the current schedule calculated considering all project constraints.

Finish Latest shows the latest date of activity finish that does not delay project completion (with activity start not moving).

DRAG shows activity contribution to project duration. In particular it shows project duration change if activity duration will become zero.

Free Float shows activity delay that does not delay any other activity in the current resource constrained schedule.

Total Float shows activity delay that does not delay project completion in the current resource constrained schedule.

Start Flex shows activity start lead that does not affect scheduled dates of other activities.

Finish Flex shows activity finish delay that does not delay any other activity in the current resource constrained schedule.

Super Float shows activity finish delay that does not delay project completion in the current resource constrained schedule. We are thinking of renaming Super Float to Total Flex, and Flex to Free Flex (for Start and Finish).

Please look at the sample project that shows these fields values.

Flex&SF photo FlexSF_zpscgclzifn.jpg Late dates in this schedule are calculated taking into account resource constraints and are shown as hollow bars.

In this project activities 1 and 2 uses the same resource A. Activity 1 was delayed due to resource constraint and resource link is shown as dotted arrow.

Activities 5 and 6 use the same resource B and again activity 6 was delayed (shown by dotted arrow).

Activities 5 and 6 are critical and have one day DRAGs. Other activities have positive total floats.

Activity 7 has both Start and Finish Flexes, activities 3 and 4 have only Finish Flexes.

Activity 3 has different Total Float, Finish Flex and Super Float. Its Finish may be delayed for three days without delaying any other activity and for four days without delaying project completion.

Project has 7days/week calendar.

Rafael Davila
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Vladimir,

As always thanks a lot. 

With the new menu option "View" it is easier to navigate to views like WBS Chart, Time Location Chart, Cost Components and many others, even when we already had access from the Tool Bar and Main Window.  I will mostly use new menu option but at times will continue using the other options.  Depending on what I am doing I will customize the Tool Bar for easier access to some views but will be able to access directly other windows from the new View menu without having to go to Main Window.  Needless to say Main Window is still invaluable to navigate among opened projects as well as opened documents, impossible to stop using it for some navigation needs.

About the view of basic double lag information on the Predecessors/Successors column at Gantt it is as expected but not sure if it is new or if it was already available.  Impossible to see all link parameters within these columns but it do help.  I just added 28 link user defined field easily visible at the links table, impossible to show them all at a single column.  There is no substitute to the links table view.

I cannot live without the Standard Reference Books functionality that makes easy the transfering of the UDFs, Formulas and Scripts to any other project.  I use codes with an added prefix for the items I will transfer among several jobs to make sure there will be no duplicate or conflict.  This coding add some clues about what the field means when you look at the formulas.

The new formula will be of much help to get the values at a single click rather than manually calculating the values for every line on the links table.  I suspect a few Spider Project users must be already doing some calculations impossible or impractical without these formulas and scripts and hope this new formula will be of help.  It looks like users will be able to explore exotic float and link calculations.

  • Do not forget I am looking for start of Start FLEX as an available field, while shown in Gantt image as a narrow bar the date is not visible to the user.
  • Flex Start&Finish
  • As well as Finish of Finish FLEX it might be calculated by formula but I believe both shall be available fields.

Best Regards,
Rafael

Rafael,

this function does not exist at the moment but we will add it soon.

You may notice that in the last version most proposals of this discussions are already added.

Thank you for good proposals.

Best Regards,

Vladimir

Rafael Davila
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  • I have Date1, Diff_Days_Calen and Calendar Code. I am looking for a formula that will yield Date2 given the other values I know.  I am looking for a formula that will change a date by the difference in days/hours by calendar.
  • BTW I am figuring out some tricks on the use of formulas and script editing that are making it easier to handle multiple If statements by calculating several formulas in sequential order.  Formulas in combination to scripts are very powerful; some calculations are impractical to do without the script.

Best Regards,

Rafael

Diff_Days_Calen (<Date1>; <Date2>; <Calendar Code>) - the number of work days between two dates in selected calendar

Now I has limited access to the Internet and soon will answer other questions.

Excuse me for delays.

Rafael Davila
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IncDays_Calen

How can I change a date by Diff_Days_Calen?

Rafael Davila
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It is interesting to note how double links lag2 perform. As you increase the value of Lag2 the finish of successor activity is advanced instead of delayed.

Double Time Lag Reverse Logic

Rafael Davila
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Double lags are visible in the Predecessors/Successors column I wonder if double lags were visible long ago because otherwise it would be too soon! Sorry for any inconvenience.

This is what I was looking for, I can look for lag calendars and any other link parameter at the links table.

Double Lag in Pred&Succ Column

Thanks.

Rafael Davila
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Relationship Formulas 02

In addition to RFF and RTF I am also looking for Active Elapsed and Active Remaining Lag.  So far for simple time and volume lag looks good, next will be for double lags [time/volume/both].

Relationship Formulas 04

As usual with a script and a single click of the mouse everything is calculated in the right sequence.

Best Regards,

Rafael

Rafael Davila
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  • I am having issues to differentiate Start[Early] and Start fields.
  • I am looking for ES if Interruptible [Start of Start FLEX].

Start Early

Rafael Davila
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As per PMI: https://www.pmi.org/learning/library/basics-cpm-scheduling-software-axon...

  • Early Start (ES): Earliest date the activity can start
  • Late Start (LS): Latest date that the activity can start without causing a delay to the project completion date.
  • Early Finish (EF): Earliest date that the activity can finish
  • Late Finish (LF): Latest date that the activity can finish without causing a delay to the project completion date.

In Spider we have:

LSD003

LSD002

  • What is the difference between Start [ASAP] and Start [Early]?
  • What is the difference between Finish [ASAP] and Finish [Early]?
  • What is the difference between Finish [ALAP] and Finish [Latest]?
  • What are Spider equivalents to PMI Early Start (ES), Early Finish (EF), Late Start (LS) and Late Finish (LF)?

I believe clarification can be included as part of the Default name to include PMI equivalent name; see next figure, no need to mess with field codes and always visible.

Field Name

Best Regards,

Rafael

4thJuly

Rafael Davila
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It also came out the logic for the script can be complicated and that some logic commands would help.  For simple time lag formulas are easy, it gets complicated when you add double links and volume lags.

Rafael Davila
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Very frequently I am having to open other windows available under Main Window and believe a pull down menu item for this purpose will be better than moving to the Main Window as the vertical icons bar is only good for a few icons.

View Menu

 

Or under Window as new menu item Main window documents next to current Main Window menu item.

MainWindow

Marcus Possi
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I do agree with the idea Rafael. It would facilitate us to identify double link use.