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Critical Path

4 replies [Last post]
Tue, 2006-05-09 04:13
wilfred datinguinoo
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Guys,

Need help! How to generate critical path for the whole project if the all the activities are all 100 % complete.

Thanks in advance guys

wilfred
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Replies

Tue, 2006-05-09 18:23
#1
wilfred datinguinoo
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Groups: Petro-Chem / Oil & Gas
Thanks guy

Appreciated

regards,

wilfred
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Tue, 2006-05-09 07:06
#2
Paul Harris
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Wilfred

An interesting question.

I have come across a reputable claims expert that stated they have the ability to generate an as-built critical path when all the activities are entered in a scheduling software package and are marked as 100%. These reputable people were not willing or able to demonstrate their method in a dispute resolution process and they stated it was a proprietary method that they were not prepared to disclose!

A critical path may only be generated when activities are not marked as complete. This is because once an activity is marked complete it is not possible for the software to compute the float and therefore not possible to calculate the Critical Path. If you want to calculate the critical path for a complete schedule then all tasks need to be un-statused and not have an actual start date.

I my opinion, to calculate the as-built critical path the as-built schedule has to be built as the project was built, with the actual durations and relationships entered so tasks are scheduled to start when they actually started. Scope changes and delays may have to be entered and often activities have to be granulated into more detail to achieve a logical schedule. Then the as-built critical path may then be calculated. This process of rebuilding a schedule is very time consuming but may be achieved if the historical data is available.

I also have one client that in their normal course of statusing a project does not mark activities with actual start and finish dates when they status the schedule. They adjusts the schedule on a continuous basis and at the end of the schedule they have an as-build critical path because there are no actual start and actual finish dates in the schedule as it was continuously adjusted during construction.

You may wish to read Mr Ron Winter’s article on Determining Actual Critical Path at http://www.ronwinterconsulting.com/raasbuilt.pdf.

Also page 3 of http://www.mbpce.com/news_pubs_london.pdf give some insight into the process required to prepare the as-built schedule but does not go into specific techniques.

Paul E Harris
Eastwood Harris Pty Ltd, Melbourne, Australia
Planning and Scheduling Training Manual & Book Publishers & Consulting
www.eh.com.au
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Tue, 2006-05-09 06:57
#3
John Ferris
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Hi,

I reckon that you need this to generate data for any claims situations ?

If the whole network is there with original scope and logic with a full % complete marked-up and acts closed out with no original target file then to generate the CP you have to look at various points in time. As the CP will change with respect to progress at any data date. So the 1st stage would be to generate the CP at the original data date just prior to the start of the project as follows :

if the project started say 01MAY04 then do the following

1. copy the file and rename as tar1;
2. set the data date to 30APR04;
3. do global change and remove actuals eg

in global change AS="",AF="" & PCT=0 (Percentage to zero)

4. reset in global change Remaining duation to Original Duration eg RD=OD

5. run all global cahnges and the reschedule at the original data date

6. this provides the original target schedule.

7. Filter on Total Float = 0

8. sort as required and this is the selection of critical acts = the critical path if logic is present.

DO ALL THIS ON THE COPIED FILE TAR1 ONLY AND RETAIN A COPY OF THE ACTUAL FILE YOU HAVE.

For intermediate CP’s you will have to go back to project records and update retrospectively at the point in time you require.

The delay from a critical path item to the actual duration of the cp item will generate the points for the purposes of claims etc....

hope this helps

John.
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Tue, 2006-05-09 08:04
#4
Ronald Winter
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We have been doing what you describe in our Schedule Analyzer Forensic software package since 1998. The module is called “As-Built Critical Path” and it ‘destatuses’ a schedule backward from the end of the project to the beginning one day at a time and notes what was current and critical for each day.

I personally just finished presenting a paper on the exact ‘manual’ process at this year’s PMI College of Scheduling in Orlando, Florida a week ago. This same subject was presented at the AACEi Annual Convention two years ago. It based upon well-known CPM principles and is (as is with most things,) obvious once you understand it.

You can read more on the As-Built Critical Path program on the web at http://www.ronwinterconsulting.com/forensic_over.htm The paper that I presented to the AACEi in 2004 is also available on our website at http://www.ronwinterconsulting.com/raasbuilt.pdf. Good luck!
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