As Built Critical Path

Gerry

Just look it is next to the Elbow Grease.

Hi Gerry,



Now you finally found the skyhook, go to the stores and draw a longweight.

Hi David,



The thread is moving faster than, you can open it or save your abswer, due to it’s size:-)



I agree, with everything, except the term AS Built CRITICAL path, call it anything you want to. I also believe that as I earlier stated, that unless the person was involved with the project from beginning to end, or unless every fact was completely documented or minuted, and agreed, it will be very difficult to analise it, I speak from experience.



Regards



Philip

Gerry,

we usually create very detailed schedules for construction works with the activity durations that not exceed one week. Contracts define target dates for major milestones and these target dates incorporate agreed contingency reserves.

Vladimir

Happy to know that the wave is seem to be settled on the As Built Critical Path issue ................... Its time for voting as per Philip Jonker’s suggestion.

Hi Guys,



I just had a nice relaxing weekend and have been catching up with all that have been said.



The one subject that seem to have cropped up since my last contribution is a "project without a schedule". Can somebody please define that one for me, I can only understand it as a project for which no planning was done, in which case it does not belong in this forum. Otherwise, I seem to sense that it was not scheduled in the normal way, ie by P3 or MSP etc, ie a computor, but it could have been done in the old fashioned way, as I was taught before the advent of PC’s.

The second point is the notion that a project cannot be completed overnight, in fact a project can be completed in a matter of seconds. What is the definition of a project. There is three areas in every project that is looked at, cost, time and quality, if there is risks involved in any of these areas, and dependant on the amount of risk the undertaking can be rated as project or not. Thus a wedding or a Formula one tyre change can be regarded as a project, and if the pre-planning is disregarded, then what I said about seconds holds true.



Further I agree with Vladimir and Philip, the two previous contributors, as they seem to be saying much the same thing. The as-built CP is a hypothetical notion somebody has thought up, when trying to analise a schedule where the job has been done. Depending on the reason/s for the analysis, whether for a claim, or to establish how future jobs can better planned, there is much simpler ways of getting to the right answers, whether it was a good or a bad schedule. I have stated this earlier, this proves the necessity for proper resourcing of schedules, as well as for good costing practices.



Maybe it is time for a vote:-) Pro as-built CP or anti?



Regards



Philip J

Philip,

let me express my oppinion:



a) The critical path is an assessment of those activities (from now until the end) that could delay the project if themselves delayed. CP in the past is therefore an irrelevance.



It is not quite true, CP does not take into consideration resource limitations. It is true if resource constraints do not exist. CP in the past is useful for the project performance analysis post mortem.



b) By my definition, therefore, there can be no critical path on completion, so no As-built critical path



As Built Critical Path shows which activities and delays defined actual project duration.



c) An hypothetical CP could be constructed from the as-built schedule (which records actual dates, suspend, resume, resources etc). This is useful in informing the next project, in improving the start-up planning



Right, it is useful for lessons learned and for claims assessment.



d) The reconstructed CP is HIGHLY subjective. If the as-built is to be used for a claim, then avoid any links and restrict the plan content to fact, that which can be evidenced.



Right! That is why I wrote that all delays and their reasons should be documented and included in the project model.



e) Above all, remember that the CP is not factual. It relies on a subjective assessment of the relationship between semi-factual activities. Even when activities have been completed, it is still very difficult to ascertain the ’true’ relationship between them.



I don’t agree with the subjective nature of activity relationships.



d) As to whether there is a CP in a project without a schedule - this is largely irrelevant. The CP is one’s idea of the longest path. If one has no ideas (i.e. no schedule) then one can have no concept of a CP. Again, the CP is not an absolute, it is based only on the assumptions made by those involved.



CP is usually based on the technological restrictions (roof after walls, etc.), it is not based on assumptions.



Hope this adds rather that subtracts!

Dear All

If I may make some contribution here and in way of trying to summarise and add to what has gone before:

a) The critical path is an assessment of those activities (from now until the end) that could delay the project if themselves delayed. CP in the past is therefore an irrelevance.



b) By my definition, therefore, there can be no critical path on completion, so no As-built critical path



c) An hypothetical CP could be constructed from the as-built schedule (which records actual dates, suspend, resume, resources etc). This is useful in informing the next project, in improving the start-up planning



d) The reconstructed CP is HIGHLY subjective. If the as-built is to be used for a claim, then avoid any links and restrict the plan content to fact, that which can be evidenced.



e) Above all, remember that the CP is not factual. It relies on a subjective assessment of the relationship between semi-factual activities. Even when activities have been completed, it is still very difficult to ascertain the ’true’ relationship between them.



d) As to whether there is a CP in a project without a schedule - this is largely irrelevant. The CP is one’s idea of the longest path. If one has no ideas (i.e. no schedule) then one can have no concept of a CP. Again, the CP is not an absolute, it is based only on the assumptions made by those involved.



Hope this adds rather that subtracts!

Yes, you are right. Logical restrictions that were established at the project start should be kept. If they were wrong then it is a cause for lessons learned exersize. But you shall add delays and additional work to the original network.

Vladimir,



What does the path that you have identified ’mean’ then?



From your earlier postings, you appear to have maintained the original baseline programme logic links to establish the ’As-Built Critical Path’. Is my understanding of your methodology correct?



Roger Gibson

Sure,

Critical Path may change during project execution and many times. That is why you shall include in As Built Schedule all delays that occured with the description of events that cause these delays. As the result you will see what chain of activities and delays constitutes As Built Critical Path. It does not mean that at any time in the project life this path was critical in the project schedule.

Hi Vladimir,



I think it’s possible but highly improbable to have a logically linked as-built activities at the end of the project.



Experience would tell us that your CP at the start may not be identical a month after, 2 months after etc. and moreso at the end of the project. "Not identical" means, it may have similar activities for each periodic CP but may not be 100% identically the same path.



Se

Phil,



With your use of the words “I do not believe that anything that is completed can be critical”, I would have to agree. It can no longer be critical if it is complete – that makes perfect sense.



However, I am sure that you would agree that it can be said that something was critical in the past. It’s not critical now, but it was earlier. That is of course if it was on the critical path that ran through the longest chain that determined the overall project completion date, or phased completion date.



I cannot agree however with you last paragraph. To say that only the planner who was involved in the project can determine the true accurate facts is clearly wrong. I will quote the example of the Great Eastern Hotel project referred to below in this thread. The judge found that the planner who was involved in the project got it wrong and this was exposed during the trial by a 3rd party planner (me) who was not involved during the project and who only became involved after the project was finished.



David is quite right – very often the independency of a 3rd party planner can see the situation better than the planner involved at the time. On the Great Eastern Hotel, I and a colleague spent over a year examining the facts to determine where the critical path actually ran through the project. Hearsay or conjecture – no way!



Gary France

I mean logically linked as-built activities loaded with resources, costs and other actual information that should be compared with the original estimates.

I repeat that during project execution all schedule delays should be included in the schedule preferably like additional activities (delays) or lags, imposed dates are worse for the future As Built Critical Path analyis.

You had logic in the initial schedule. What happens with this logic? You had done the work out of sequence? It means that the logic was wrong in your initial schedule or you decided to use fast tracking. The latter decision should be accepted at some moment and the links in the schedule updated.

I still don’t understand what can happen with the project logic to the end of the project.

As Built Critical Path may be useful for project close out, lessons learned, etc.

I don’t understand many arguments in this discussion. Why everybody agrees that there is not such thing as As Built Schedule? Maybe you mix methodology and tools? Just imagine that you do everything manually. In this case you may update your initial schedule with the actual durations and costs and as the result you will receive as built schedule. This schedule has the same properties as any other, including critical path (only if you add into schedule events causing delays).

Gerry



Why would you like to show the as Built Critical Path. - For Future information so next time you start a similar project you can learn out of past experience. Also when you do OME lvl schedules you have a look at your past schedule and this will give you an indication as to the overall duration. (If you have similar constraint) Also why do you do project close out reports is so that you learn and adapt it for future use. (Learn out of our mistakes and implement corrective action).



What is the critical Path. The Longest Path. (Please note float is not part of my definition of the critical path because sometimes you do not calculate the float) “concept similar to float “ is still not float.



Even a Project with no schedule have a longest path. (Even though nobody know about it) My apologies Gerry I did not read the practical part.



If a project does not have a longest path we can assume that we can finish it overnight.



Maybe if you do construction planning the A.B.C.P. might not be useful but when you do project planning this data is. Besides the Q is Does an As Build CP Exist.





Cheers

For Line of Balance, although float is not applied, the game rule is similiar.

We plan for the optimum by shift the bars around; bar thickness and gradient of bars. The shift, thickness and gradient, on concept, is silimiar to float.

[Duplicate entry deleted.]

So if a project has no schedule it can be completed over night ????. No a Critical path is more than an calculation it is a fact of live.



If I make a decision to use a Line of Balance Planning (LMS) system on a hundred Kilometer pipeline I will not have a critical path because I can not calculate it due to a Line of Balance can not calculate float (No CPN).

Philip



Hearsay and conjecture - I agree we don’t want that.



But what about what Gary F did on GEH - an objective, practical and thorough analysis of the FACTS (including identifying the route of the ABCP)?



By the way, to hearsay and conjecture I would add dynamic programme analysis (particularly Time Impact Analysis) undertaken without due care.



David



p.s. what are your answers to my earlier e-mail?

I agree.

Critical path, besides it is defined as the longest path, is usually defined by TF=0. If no schedule, all the above is not exist and so, what is the measurment criteria?

Gerry,



Do you mean a critical path with logic links/relationships between activities; or a graphic presentation of activities showing what was critical to project completion at any particular time over the life of the project?



Roger Gibson

I understood that this discussion refers to contract schedule. In other case traditional critical path will not define project duration if resource constraints are taken into consideration. Resource Critical Path (or Critical Chain) takes its role and defines project duration.

Contract schedule may change due to the various reasons - delays, change requests, risk events, etc. Activity start dates may be delayed not in accordance with the schedule logic. Due to some events not necessarily the longest path will be really critical.

So if you want to be able to restore As built Critical Path all events that lead to delays shall be included in the project schedule with the corresponding links that show which original activities were delayed due to any event and which preceeded delay. Of course you may find critical path using Float less than, not just zero float.

If it was done during project execution then As Built Critical Path can be restored.

Hi Gerry



I still say a As Build critcal path exist.

Does a project without a schedule have a critical path.



If your answer is yes then you must define the definition as the longest path & forget about float. (remember the project does not have a schedule). (Differance between planning and scheduling)



Also have any of you used why before. Once you have completed a schedule ask yourself why was the project not finished earlier and then go through the activity’s one by one and ask why was this not finished earlier. Eventualy you will see the true as Build Critical path.







Cheers

Gerry,



Don’t you mean “I don’t mean to be critical but….” ?



Me ? Plan?

Couldn’t plan a piss-up in a distillery on Hogmanay!



Cheers,



Stuart

www.rosmartin.com

Hi Gerry,



My views have not essentially moved from that of my earlier posts; if anything, however, my expressions may have modified! I now accept (thanks to the clarifications offered by this thread) that the term “As-Built CP” is at best misleading and at worst entirely wrong! ;-)



Against the background of the clarifications offered by this thread, I would say that I haven’t changed my mind – just my words!



Cheers,



Stuart



www.rosmartin.com

Hi Staurt,



I don’t think there is a name for it so just call it the longest path:-) The point being that if the project finished early the longest path was never critical. Further if the project finished exactly on time or late, and the last activity was say "Handover", There would probably have been some other chain of activities linked to the final activity, so it might not necessary have been the longest path activities that forced thee project to end late. So again give one good reason for bothering with a so-called "As-built CP".



Regards,



Philip

Hi stephen,



The question is not what critical path is, I agree with you during the execution of the the project, however, when the project is complete, it is something like an post mortem, how can you find an ilness in a corpse, that is critical, you can only analise what the problem was and try and prevent in the future.



Regards



Philip

Hi Staurt,



I don’t think there is a name for it so just call it the longest path:-) The point being that if the project finished early the longest path was never critical. Further if the project finished exactly on time or late, and the last activity was say "Handover", There would probably have been some other chain of activities linked to the final activity, so it might not necessary have been the longest path activities that forced thee project to end late. So again give one good reason for bothering with a so-called "As-built CP".



Regards,



Philip

Stuart,



I would call if the ’Actual Critical Path’. It is the sequence of activities over the life of the project that caused the completion date to be delayed from ’x’ to ’y’.



By using the ’windows’ or ’salami slicing’ methodology, (’windows’ sounds less painful Stuart)then this path is established.



Also, as it is often the case that an activity may be only be critical for part of its actual duration, I don’t know of any planning foftware that can determine and graphically show this from a final as-built project with actual start and finish dates for each activity.



Roger Gibson

Hi Philip,



Yes, I agree – which is why we should stay away from the term “Critical Path” insofar as an As-Built Schedule is concerned. What therefore, would you call the longest line of activities through an As-Built Schedule?

Isn’t this where it all began?



Cheers,

Stuart



www.rosmartin.com

Hi Stuart,



It is like magic, here today gone tomorrow.



The point is if an activity is complete it’s float disappears.

Very interesting thread (now that I have caught up with it!), and I think that we are mainly reading from the same page. I would agree with Roger and Gary about the “snapshot” or “windows” approach – personally, I stay away from the word “windows” to avoid confusion with u-no-what; I prefer to call it “sausage or salami slicing!”



Unsurprisingly, we all seem to agree that the CP runs forward to the end of the project (starting now or at some other point in the future) and we all seem to agree that the CP can multiply and can flit around from day to day. Ronald’s last post (!) emphasises this point. However, I am unsure as to whether this answers Gerry’s earlier question as to what you call the CP once it is consigned to history (i.e., what do you call today’s CP tomorrow when it becomes yesterday??) [Thank God no lawyers are taking part in this discussion!!]



In addition, from a claims entitlement point of view, I would just add that if your Baseline Schedule is itself incorrect and unreasonable (subjective definition anyone??) then the formation of an As-Built Schedule that emanates from said Baseline Schedule, will itself be incorrect.



Cheers,



Stuart



www.rosmartin.com

[Duplicate posting deleted.]

Hi Sigfredo,



What you say is true. There is one thing however, that is a useful tool, that is saving the history after each each update. P3 has this feature in store period performance. Using this feature has two advantages, one , in that S-curves and histogrammes give a better reflection of actual events, and secondly, where delays occured they can be tracked correctly in the the event of a claim. The value of stored period performance is obviously dependent on the frequency of updates, the more frequnt the updates, the more accurate the stored information. One of the biggest and serious causes of productivity losses is disruption of activities.



Regards

Philip

what about coding the critical path networks say cpm1, cpm2....(the ranking of numbers 1, 2 will be based on the longest critical path compared to the next and so on....) in the baseline program itself so that it would be useful for monitoring the changes of critical path if any during update period and that can be used for tracking as built critical path if it exists so.

Hi guys,



Just want to share my ideas on the subject.



1. It is a fact that a Critical Path(CP) today may not be the same tomorrow, next week, next month etc. Unless someone will dispute this fact, please feel free to discuss it.



2. In comparison, as built CP is not the same as as-built drawings. As built drawings can not change meaning if a foundation size on the original plan is 2mx2m and it is actually built at 2.5mx2.5m, no one can dispute that what was constructed is a 2.5mx2.5m foundation because you can easily prove it. In As-built CP it is ever changing. What you may have as an as-built last week may not be the same tomorrow.



IMHO, I believe the word As-built CP is not the most appropriate term. I think History of Critical Path is the better term.

Hi Jaco,



The commonly accepted definit1on, of a critical path is a chain of activities with total float of zero or less, you can decide whether you want to increase the figure to more than zero, if I am working in days, and dependent on the overall duration of the project, I might increase the criticality to up to a week. The reason for this is to be able to spot all activities which is problematic, or might become a problem. You can also say that it is the longest chain of activaties in the project, however this is not always true, as the longest chain might be ahead of schedule, and another shorter chain might go critical, because of intermediate completion dates, resulting from commissioning procedures or other constraints.



Regards



Philip

Hi Guys,



As I originaly stated I do not believe that anything that is completed can be critical. I also have a problem with the name ABCP, it should probably be called something like delay analysis.



If the planner who was responsible is doing the analysis, ie writing a report on the problematical activities or areas, I would tend to believe the accuracy of the facts, dependant on the quality of the historical data, and planning. But where another party, that was not involved inyimately with the planning or the project, during the execution thereof, I would write it of as hearsay or conjecture.



Regards



Philip

Hi Phillip



Can you please supply us with your definition of the Critical Path.



Thanx

Hi Ronald,



I already mentioned the point about the critical path moving, however, I understand the project in this instance is already completed, hence "as built". If it is partially completed, yes there will always remain a critical path , and if it is behind schedule you may even have two or more critical paths, and in the instance where the project is well ahead of schedule, the critical path can disappear.

In my experience one of the best ways of analysing a completed schedule is by looking at the costing data, ie performance factors. When I speak about costing, I mean using budget manhours against each activity, and recording actual (clocked) manhours to calculate performance factors.

These performance factors can be plotted against time or % progress, or for individual phases or discplines for the project. If you look at these curves, it will help you in future projects of similar nature to adjust budget estimates, which in turn will give you a better idea on how to work out durations. I have found this a valuable tool in the past where we repeated the same job twice but reduced the duration of the second project by twenty percent.



Regards



Philip