Out of Sequence Activities

Dear Ali nobody can gives you an exact answer for this question because it depends on the effect of this activities maybe the out of sequence activities have minor effect and this activities will finish after a few days in this case you keep this activities in other hand the out of sequence activities could make a majore effect in the schedule and giving an wrong indication for the overall schedule and critical path and in this case you should review the schedule and change the network logic.

Finally you decide the solution acording the effect of this activities in the overall schedule Case by Case

Khalid Abdelaal

Ali:

In general, we usually have two types of relationships in a schedule: mandatory and preferential.

Mandatory relationships are those that represent physical requirements like having formwork placed before pouring concrete.

Preferential relationships might represent desirable sequences like to obtain a higher level of quality. Or they might follow a defined (desirable) project procedure.

Other common reason for using preferential relationships (not my way of doing things though)is due to resource availability.

Some planners build into the schedule a sequence they envision should be followed to resolve a resource problem. If activity A and activity B use the same resource, they place a relationship between those two activities.

If the out of sequence condition refers to mandatory relationships either there is something wrong with the logic or there is a mistake in the progress update data. You need to fix these cases.

Probably investigate at the site what is going on, there might be some change in site or project conditions. Or there might be a change in the technology used during construction.

If the out of sequence condition refers to preferential relationships, then the people at the site are executing the project in a diferent sequence than what you envisioned or proposed. It might be just a diferent way or style of doing things or they got more resources than expected. You either change the sequence or delete it altogether.

If this condition refers to a sequence you determined advisable to get a certain level of quality or to follow an established procedure, I would sugest to you to leave it as it is.

This way your updated schedules will keep showing the sequence you determined. If the guys at the site want to do it in a diferent way, well that is their desicion.

My final recomendation is to keep preferential relationships to a minimum.

I hope this helps.

Tomas Rivera

I read all the replies to the question about out of sequence.

To me I believe the simple answer to the question is, out of sequence activities happen when what you originally planned sequence is not what actually happening sequentially.

Mr. Tomas Rivera,

I was englightened by your definition of mandatory and preferential relationships. We basically schedule the same way. But I didnt know that the terms mandatory and preferential relationships existed. These terms sure brought a new level of understanding to me.

Thank you.

Jorge
Crown Systems

Try also to read about Schedule level calculation option, mainly for the Retain logic and Progress override. Maybe this can help.

Out of sequence activities are normal. It always happenning that the site people adopts flexibility in carrying out the works, not necessarily always according to the programme. We normally correct the logic and report the effect of the changes to overall completion date. If it did cause delay, then you have a lot of explaining to do why its been done.

Most of the time it could be avoided by detailing the activities to the lowest level as possible. But its not a guarantee. Improving communication with site level will always help by explaining the importance of following the logic of the programme. This is if the programm has logic.

For further info about this subject matter visit: www\pmi.cos.org

PMI College of Scheduling discussion on Progress Override Vs. Retained Logic

Bernard Ertl
InterPlan Systems Inc. - Project Management Software, Project Planning Software

In my experience when I find out of sequence, this is often due to people taking the easy option and not completing those activities on the critical path! BUT want to be seen as being very busy.

When out of sequence is occuring I find that great care needs to be paid to the "increasing risk" of the project end date, or key milestones slipping to the right. Often in project reviews when probed the risk to achieving completion is increasing where out of sequence has been recorded.

In a simple linear programme, the retain logic or progress override options maybe used depending on the effect of the out of sequence activity on the programme. However, we have to keep in our mind that only one option could be used.

If the out of sequence activity is not in the critical path then it could be nothing to be concerned about. The point is, if every single day delay is causing the client to jump or the contractor would have to pay huge amount of LD, then an accurate statusing of the programme is a must.

For a programme with complex logic, or if we used a lot of those preferential relationship to hide the floats, the out of sequence activity could possibly have a substantial impact in the programme.

To make myself comfortable, I always take a close look on how the out of sequence activity is affecting the logic of the programme. And most of the time I ended up correcting the logic.

Of course am not sure if this is a good practice. Would you like to share you experience guys? Am happy to be enlighted.

Regards to All

Hello everybody

For some reason, Consultants prefer the "retained logic" option.
In your opinion, can the consultant impose this option on the Contractor? This will require the Contractor to review at every update the out-of-sequence activites and adjust their links. This will also mean that if 50% of the program are preferential, than these 50% may have to be changed later on during the updates if their soft logic has changed.

Please refer also to my new post.

Joe

Attached is the write-up by myself regarding Out of sequence, Retained Logic, and Progress Override in P3. Please review for your reference.

Go to the
http://www.htcprojectcontrols.com/SB002.pdf


Eric Chou, PE
HTC Project Controls, Inc.

Dear Eric,

Your explanation on Out of Sequence Progress in Cyclical Network was really fantastic. I follow it in the sameway as per your sample construction schedule as mentioned in item 4. i.e changing the logics to reflect the current sequence and calculate the schedule by using retained logic.

In connection with the above, I would like to raise a question. How frequent a contractor is allowed to change the logic in the schedule update?. If the contractor changes the sequence or logic in every schedule update, does it mean that the contractor is not having a firm plan in his hand?.

I welcome our fellow planners opinion.

Regards

Daya

Dear Daya,

To further clarify my points:

1.     Other than the situation of cyclical network, the out-of-sequence progress (I mean a P3 term) does not need to be “corrected.” (again, I am not talking about a wrong logic) As soon as the out-of-sequence progress activities are complete, the abnormality to the schedule calculation is no longer existed.
2.     In the situation of Cyclical network, the skewed network presentation always force readers to question the CPM, therefore, the scheduler has to change the logics to reflect the near future plan. However, if you don’t change the logics, you still get a correct forecast calculation for the remaining of the schedule (after the last activity of the group of cyclical netwrok) by using Retained Logic option (as shown from my examples).
3.     Therefore, your question is no longer a question. If the owner allowed, I will change them to reflect the actual sequences. Otherwise, I would leave them unchanged. However, I would not use the Progress override option at all. Unfortunately, I realized PMI is promoting the use of Progress Override option, which has caused a lot nuisance on my job with some owners. That is why I wrote the article to convince them otherwise.

Eric Chou, PE
HTC Project Controls, Inc.

I agree fully with Eric. Progress override can be a big nuisance for projects with large number of activities or projects with short (weekly) reporting periods. You will be spending most of your time correcting logic to retain a sensible schedule.

Naveed Shakoor,CP Engg., PMP
STC.