As Built Critical Path

Daya,



Jaco has defined it correctlt; it is the longest path that is established. However, this is often termed as the ’As Built critical path’.





Roger Gibson

My answer is yes.



An as build longest Path can be produced. I would suggest to forget about the logic issues. Please note the diffinition of a critical path is the longest path. Not the longest path due to logic. With other words if the logic is wrong (We are all human) the critical path is something else than the longest path.



But why do you require this. I am not sure what type of project you are working on / or refering too.



Cheers

Gerry,



Personally, I don’t think an ’As Built’ critical path with true as built logic can be created. Just because activity B started 3 weeks after activity A started does not mean that the as built logic between these activities is a start-to-start of 3 weeks. It could be because of a number of factors, e.g. shortage of resources or awaining information.



In carrying out a retrospective analysis of actual delay my preferred approach is a series of progress snapshots, or ’windows’, which show which activity was critical at each snapshot. From this, and further investigation and interrogation of the network, progress and other records an ’As Built’ critical path is established.



Roger Gibson

Gerry,

Whilst it is acceptable to change the logic by adding links in creating an As Built Critical Path, it is important to justify and explain the reasoning for each change.
Another important ’verification’ check of the As Planned network are the activity durations. I have often seen eot/delay calculaions based on original programme durations that were excessive and therefore resulted in eot/delay calculations being longer than reasonable or realistic.

Roger Gibson

Gerry / Stuart,



I agree, there is nothing inherently wrong in adding retrospective links. In fact, you must do it because chances are that the original programme logic will have changed over time. Apologies if I didn’t make that clear.



Gary France

Chairman

Planning Engineers Organisation

Gerry,



Gary is right that you have to take care when you add in retrospective logic – hence my caveat about ensuring that there are no inconsistencies with the original logic.



In principle, however, provided that your logic is sound and reasonable, there is nothing inappropriate in inserting retrospective logic (subject to the points that Gary and I have made).



Cheers,



Stuart



www.rosmartin.com

Gerry,



Can we assume that you are putting together some sort of a claim document to demonstrate what actually happened on a project? If you are, then you have to be very careful in adding links retrospectively. You will / may have to justify each one if they are different from the originally programmed logic. This is because, by introducing new logic, you might well change the critical path from that which would have occurred in your as-built programme had you retained the original logic.



Many experts / delay analysis consultants have been criticised for adding retrospective logic that change the critical path. In effect, by adding links retrospectively, you can make your as-built critical path show whatever you want it to show. Be wary of falling into this trap. You will need to be certain that you can justify all changes, because if you do not, or cannot, than be prepared to do battle big time with whoever you send this to.



Good luck.



Gary France

Chairman

The Planning Engineers Organisation

www.planningengineers.org

Gerry,



Provided that the logic as inserted is not inconsistent with the other related activities, there is nothing wrong in adding it into as-built already-constructed activities.

This happens all the time when trying to demonstrate that a Delaying or Relevant Event (call it what you will!!) has had an impact on the CP.



Hope this helps



Cheers,



Stuart



www.rosmartin.com

Gerry,

It is essential that an as-built CP is developed if an argument arises over EOT to a Contract.



The as-built CP will sequentially trace the work activities that were executed for the project to reach completion, or up to the time under consideration. If completion is reached, or shown to be reached, later than originally planned, then you have a delay. If all or part of that delay is attributed to reasons not applicable to the Contractor, then the Contractor may be entitled to an EOT, which may equal all or part of the delay.

Subsequently the Contractor may be entitled to costs related to the EOT.



But the foundation for all of this is the as-built CP. If the Contractor cannot demonstrate that the as-built CP was pushed out for reasons not attributable to himself, then he cannot claim an EOT.



And remember that an as-built CP is not just the final one produced at the end of a project; it is the CP that has occurred from the start of the project up to the time in the schedule under consideration.



Cheers,



Stuart



www.rosmartin.com

A Complex discussion even though it seems simple.



The definition of the "Critical Path" is the longest Path through the schedule and the answer is yes.



I have observed that you will always have a critical path (more than one) in the process industry. But what I have noticed is that the path will change during the project live from planned to final (Different Activity).



The reason why is once a critical path has been identifyed the project does everything in their power to reduce the critical path once you have reduced it you will noticed that something else becomes critical. And then you would do everything in your power to reduce this.



Also you end up giving more slack (delay) on your non critical activity’s so that you can address your critical path.



So in the end of the project you end up with various critical paths (also called a photo finish)



So yes "critical path" does exist in As Build Project I sometimes use the Term Critical Chain (Everything Finishing together but all part of the Critical Path) but I know that somebody is marketing "Critical Chain method" I have not seen what their definition of a critical chain is.



If it was not for the longest path we will be able to do a project overnight.





Cheers

Dear Jaco,



What you have said is correct, The longest path is the critical path. As Built Critical Path is based on the actuals happening at the site i.e. based on the actual update; when the project is in progress due to the rate of progress of work experienced at site the original critical path(or the baseline critical path) could be altered and may be at the end of the project a new longest path could be found than the expected one. Once the project was over we can say it as a As Built Schedule just like saying as-built drawings. The As built schedule should reflect the history of the project in genuine. Obiviously the longest path formed in the As-built schedule would be a As-built critical path but not necessarily to represent the original baselined critical path.



Regards



Daya