What is Out-of-Sequence Progress in Primavera P6?
Out-of-sequence progress occurs from a deviation in the original planned logic that was set up in the baseline schedule. It can occur when work is executed in the field in a different order than was planned in the schedule. The result can affect your project’s logic, which dictates the order of execution of activities.
Checking for Out-of-sequence progress
To check for out-of-sequence progress in an updated schedule you can do the following. (also read how to find activities causing out-of-sequence situations in Primavera P6)
By selecting the F9 key or the Schedule hot key the Schedule dialog box will appear. There is a Log to File function that creates a summary level report from the current project. The Log to File box must be checked and a location for the file needs to be mapped by selecting the browse button (box with four dots).
If a log file has not been run in the current database a “Specify Log File” dialog box will appear. To create the log select YES in the dialog box if prompted. See graphics below.
Map and name the Log file to the desktop or a specific drive.
Dealing with Out of Sequence Progress in an updated Primavera P6 schedule
A summary report with various sections will be produced, but the focus of this discussion is the output file for Out-of-Sequence Activities within this report. This portion of the report shows the number of Out of Sequence activities, Project ID, Activity ID and the Activity Description for all Out of Sequence activities in the current project. See graphic below.
NOTE: This report should be run every time an update is done (i.e. weekly or monthly).
After running and printing the report each out of sequence activity should be reviewed and corrected (if possible). Depending on the project there can be several different types of Out of Sequence Progress occurring and each may have a specific solution.
Out of Sequence Progress : Example 1
In the first example, activity 110ERI2131 is an activity in the report above that has out of sequence progress that needs to be addressed. See highlighted activity above Example 1.
To see why the issue is occurring, the original logic must be understood. In the baseline schedule the original logic was set up as Install Lighting Conduit Columns 7-15 and was to be installed before the Lighting Conduit Columns 15-21 as a Finish-to-Start relationship. See the graphic depicting this baseline logic below.
After approval of the baseline schedule and the start of updating the project schedules, the project’s logic can always change depending on what is being installed in the field. In this instance, the logic has changed and the Lighting Conduit Col 15-21 is now actually starting first, but the existing logic (from the baseline) remains the same and is causing Out of Sequence Progress by pushing out the Lighting Conduit Col 15-21 end date incorrectly. See the graphic below.
Correcting the logic
To correct this type of Out of Sequence Progress, the logic must be altered to reflect the correct flow of work. In this case, the Finish-to-Start (FS) tie from INSTALL LIGHTING CONDUIT Col 7-15 to INSTALL LIGHTING CONDUIT COL 15-21 needs to be broken and re-tied showing the Conduit Col 7-15 as following (successor to) the Conduit Col 15-21. See graphics below.
By removing the Lighting Conduit Col 7-15 as a predecessor and making it a successor to Lighting Conduit 15-21 the Out of Sequence Progress has been eliminated and the logic is now modeling what is taking place in the field. However, in doing this, the Lighting Conduit 15-21 no longer has a Predecessor tie and cannot be left this way. A properly statused activity that logically precedes the Lighting Conduit Col 15-21 will need to be tied as a proper predecessor. Open ends on installation activities are not acceptable.
Out of Sequence Progress : Example 2
Another example from the log report would be activity 108ERI4343 (see example 2 above). The original logic (baseline) was a Finish-to-Start (FS) tie from 108ERI4343 to 108ERI4344. In the updated schedule this scenario clearly depicts two activities that are being worked concurrently while their original logic remains tied as end-to-end (i.e. Finish-to-Start).
Correcting the logic
In this scenario the logic should be changed to reflect the concurrent work (in the field) which would result in the predecessor (to 108ERI4344) tie being changed to a Finish-to-Finish (FF), lag 2 days. The lag shows that consideration has been taken to make sure the activities do not finish conveniently on the same day after changing the logic. See graphic below.
With the logic changed and the Out of Sequence progress resolved, the relationship between the two activities now looks like the graphic below.
Out of Sequence Progress : Example 3
In the last example the Out of Sequence progress cannot be resolved and must be left in place to show true representation of the work currently happening in the field. In this example activity 106EMB1010 Mobilize – WV (example 3 see above) has started but its predecessor activity 106AMWV2000 has not which is clearly causing Out of Sequence progress. See first graphic below. In this instance the owner directed the contractor to perform ductbank work earlier than originally scheduled stating that this work is unrelated to the station work which is scheduled to be performed later which would be preceded by the contractual access activity.
Retaining the Original Logic
The logic should stay intact to reflect the Out of Sequence work being performed. This Out of Sequence work should be quantified and noted in the monthly update narrative that gets transmitted to the general contractor.
As shown in the examples above, most out of sequence progress can be resolved, but where it cannot, or more importantly, where it should be retained, it should be communicated to all parties involved in the schedule clearly.
Out of sequence progress can be inevitable due to changing conditions on the project site, but how it is handled during the life cycle of the CPM schedule is the more important aspect.
Reviewing the accuracy of the schedule logic against the sequence of the installation work in the field is the key and the logic should be analyzed during every update period. Whenever logic has been revised from the baseline plan it should be noted in a monthly schedule narrative or a letter to the owner/general contractor specifying all logic changes. If schedule logic is continuously revised each update period to reflect the sequence of work in the field a full schedule review might be warranted to determine if a re-baseline plan is needed.