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How to determine the Critcal Path?

12 replies [Last post]
Mon, 2007-02-05 19:18
Skan Bu
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Hi,

My colleague & myself were looking at a programme submitted by the Main Contractor to the design team.

The Contract was based on scheduled dates say; start 5/02/07 and completion/handover on 29/11/07.

We noticed that the submitted programme version 002 do not have RED line showing the Critical Path. This version 002 is incorporated into the Contract Documents.

The version 002 was a result of amending the tender version 001 (start date 2/01/07) to reflect the actual start date (5/02/07)but still complete on 29/11/07.

Our analysis is that version 002 should be used as this is the Contract Programme but we can’t determine which activities are on the Critical Path.
Should we want to find out if an introduction of a variation which might affect an activity, whether that activity is on the critical path, how can we find out?

Just because the Critical Path is not shown on version 002, could we determine the critical path from the existing data?

What should we look out for?

Could any of you specialist/expert programmer enlighten us?
If no Critical Path is shown, does that mean the Main Contractor do not have any activities that are critical & they have committed to complete on 29/11/07 ONLY?

Thank you
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Replies

Thu, 2007-02-22 21:10
#1
Andrew Flowerdew
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Tom / Charles,

I agree that at times it maybe a game of bluff - or at least it a game to be played out and often depending on whose got the expertise, wins. Normally the contractor, no disrespect to Employers, but Employer all too often sit back and rely on the contractor for information instead of investing in someone to get thier own information - until it all goes pear shaped and the it costs a small fortune. (But I’m not complaining at that particular point!!!)

A planner is like every other "non productive" member of staff. No, don’t shout at me for that comment, I don’t mean non productive in the strictest sense! - I remember talking to an ex Engineer turned planner who told the story that he was once asked by a Client whether he earn’t his money. To which he had a problem replying because how do you demonstrate how much you’ve benefited the Client. You could say "well I’ve done this and that and sorted this and that, but how much do Clients really realise how doing this and that can save them alot of money. The same goes for planners. If the job goes well, in the unlikely event they actually employed a planner to start with, then the Client often thinks, well I don’t need them for the next project, what benefit did they bring? Planners are unfortunately it seems, for both contractors and Clients, not at the top of list of must haves on a project - in my opinion to both their perile, but my opinion isn’t going to change the industry.

So the game goes on.
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Thu, 2007-02-22 06:07
#2
Tom Howard
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"When the time comes for the clever planner to be interogated, he will just evaporate from the project"

An almost Shakespearean take on the subject Charlie, but hey that’s clever people for you... THE SWINES !
LOL
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Thu, 2007-02-22 05:59
#3
Charleston-Joseph...
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Hello Andrew,

When the time comes for the clever planner to be interogated, he will just evaporate from the project.

The newbie (new planning engineeer) will be at pain on WHY??????, WHY?????

Eventually, he will cried out WHY ME, IT IS UNFAIR, THIS IS A CRUEL WORLD OF PLANNING.

Cheers,

Charlie
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Thu, 2007-02-22 04:26
#4
Tom Howard
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This is true, but for most clients (at least the ones I have come across anyway), this would only materialise if they employed the services of a forensic planner or similar expert. They simply do not have the knowledge, experience or technical expertise to analyse programmes in this way. I suppose in a way it is a game of bluff, and as you rightly point out Andrew, the longer the discussion continues, the bigger the fall if / when it finally unravels.
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Tue, 2007-02-20 20:16
#5
Andrew Flowerdew
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Tom is absolutely right, a bit of tweaking here and there and the critical path can be influenced in just about anyway you like.

BUT:

The supposedly clever planner who keeps tweaking things along the way will soon get caught out if his programmes have to be interogated by someone else - and then made to answer for the oh so clever changes.

One of the first things you look for in delay analysis is "what has changed in the programme along the way" and more importantly why. Some supposedly very clever planners have had to look not so clever when asked the question - why!!!!
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Tue, 2007-02-20 06:57
#6
Tom Howard
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Skan, don’t get hung up on a the critical path. I produce many programmes with perfectly accurate logic, but initially have critical paths flowing through the most unlikely tasks. A simple tweak of a days duration or a change in the lead / lag of a couple of items will then TOTALLY change the critical path. Therefore a competent main contractor can get their programme to "tell" whatever "story" they require. As someone has already mentioned, once the project goes live, and the contract programme becomes a progress programme, an experienced planner can run rings around any Design Team when it comes to the delaying effect of variations and their criticality. The fact is, most clients don’t fully understand programmes, they don’t understand the software (if they even have access to a copy), and criticality can quickly be turned into a very subjective (and vague) area.

What I am saying is that just because the original critical path doesn’t run through the "variation" event, doesn’t mean that it (the variation) will not have a full and frank effect on the completion date. (Whether the M/C is being upfront and honest or not).
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Wed, 2007-02-14 18:41
#7
Rodel Marasigan
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Hi

I addition to all posted reply, if their submission are all in paper and not the electronic program itself, you check all your milestone finished date or need to be achieved and work back to the activities and determine the zero total float. All of these are critical other wise ask them to resubmit their plan showing the critical activities.

If electronic copy was submitted then all you need is to change the format of your bar and change it to red to all zero total float or critical activities. All scheduling software should have this function.

Cheers,

Rodel
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Wed, 2007-02-14 09:32
#8
Mike Duce
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Hi

In reply to the original message from Skan Bu, my views are as follows

You say that the start date has moved out by nearly a month, but the completion date has remained the same

To acheive this I would suspect that the Contractor has re-looked at the sequencing and it is unlikely the original critical path still applies. To maintain the original critical path he would have had to reduce the time on each or a number of the critical activities, which to save this amount of time overall doesn’t seem viable to me (unless he is now working overtime and completing each activity quicker)

If you really want to know the critical path can you not ask for this to be displayed on the programme and re-issued. Don’t know what basis he priced this on, but a number of standard prelim items in the tender documents nowdays ask for this information to be clearly displayed when submitting the programme.

If you wish to use this information to see if you can introduce a variation without affecting the critical path, you will still need to be very careful as even if an item is not critical it could turn critical at some point as the works progress. So in addition to the critical path you would need to know what amount of float was attached to every single activity.

If your contractor is using a planning software package properly he should be able to report this information throughout the life of the project, as critical activities and float attached to other activities will change as the works progress.
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Wed, 2007-02-14 07:42
#9
Izam Zakaria
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Dear Wise Coleagues

Crititcal activities set the schedule for the project because they must start and finish on time or else the project end date. Watch critical activities when reviewing project status...
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Tue, 2007-02-13 13:19
#10
Reynaldo Y. Calay...
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hi guys.....

critical path is the group of activities with the longest duration......

look for milestone dates these usually are in the critical path.......

try to impose must finish date on the finish milestone...........

try to filter total float equal to ZERO (0)......

the activities are not linked????????? a friend of mine encoutered that a so called planner just put duration and drag the bar .........try pressing F9 ang enter :) and hold on to your seat :)

hope this helps c",)


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Tue, 2007-02-06 04:55
#11
Charleston-Joseph...
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Hello,

Generally critical path traverse activities with zero float.

In the early days of PERT/CPM (before the advent of planning software), the critical path can be determine using simple but repeatitive arithmetical computation (no need for higher mathimatics, intergral calculus, differential equations, etc. that civil engineering students are trained). Even elementary pupils can do the arithmetical calculation.

This is term the forward pass and the backward pass.

All you have to do is go for this exercise to arrive at the activities with zero total float, not the zero free floats.

And that it guys, you get your activities with zero total float - and your critical path (just track the activities with zero floats).

It may sound daunting if you have not done this in your school days, in other words, your teacher in colleage forgot to teach you this exercise. But now you are employed, then you have no choice but to start running this arithmetic exercise.

Cheers,

Charlie
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Tue, 2007-02-06 03:05
#12
Vladimir Liberzon
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Hi,
you did not specify which software program is used.
In any case Critical Path activities have zero (or negative) Total Floats (Slack). Making them red depends on the software.
If your schedule is resource constrained then most PM software shows wrong Total Floats and as the result wrong Critical Path.
Regards,
Vladimir
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