NEC3 & Multiple Critical Paths

Hi Chris

Multiple critical paths are a sure sign that the programme has been rigged to create them - just think of the number of variables that go together to create a critical path then the chance of more than one occurring naturally is infinitesimal.

So the Employer is quite right to reject the programme.

If there are discrete sections each with its own LAD's then each should have its own critical path - that is not manipulation.

Some software such as Asta PowerProject can cope with this without "Must End By" constraints - others cannot do it.

In such cases it is necessary to create a milestone beyond the final date and link each section end date to it using lead lags of  a suitable duration so that each section shows criticality in its own right.

I call this "Forced Critical" logic.

Best regards

Mike Testro

Thanks Mike.

Could you please explain what "LAD" is?

The critical path follows along the longest path through the programme, which in general is singular. In a couple of places it splits for a short duration as there are multiple activities (2 No.) running from the same critical predessor for the same duration, then returning to the same successor. There aren't multiple critical paths running through the long sections or the whole programme just in a couple of places where you have the above mentioned scenario.

At the end of the programme, the critical path splits into 2, as there are separate completion dates for;

• "Completion of the works" (to summarise this is site works). We were asked to show a bar between our "Planned Completion of the works" and "Completion of the works". I suppose this has resulted in the critical path being rigged.

Under resource constraints multiple critical paths are common.

Resource constraints are real, that can be manipulated no doubt about it, but instead of running away we must responsibly deal with reality. 

Resource constraints can be legitimately controlled to reduce idle resources, the contractor have a right to make money and keep under control waste on idle resources. Repeating words of others, this is not manipulation. 

Some of our courts reject schedules that are not resource loaded and many of our good practice call for not using soft links, they consider soft links a dangerous manipulation of resource leveling. At one time prohibited on our specifications but suddenly after the emerging of software poor at handling resource constraints the rule was conveniently obviated.

I accept questioning multiple critical paths but not their automatic rejection, allow the contractor to prove they are genuine and not manipulations. 

I accept questioning of limits on resource availability but not their automatic rejection.

I accept automatic questioning when some any other additional guidelines are broken but never their automatic rejection.

Chris,

The contract allows for only 4 reasons for the client to refuse to accept a programme:

1) the Contractor's plans which it shows are not practicable

2) it does not show the information which this contract requires

3) it does not represent the Contractor's plans realistically

4) it does not comply with the Works Information

It sounds like he is arguing point 3 on a similar assumption to Mike's that multiple critical paths always equals artificially manipulated programme. (As an aside, Mike: this isn't true. I've built a couple of programmes in my time that happened to have 2 parallel and equally critical paths. I'm sure I'm not the only one)

But from the situation you describe, this doesn't seem to be the case. You describe your inital response in your OP, did the client reject that response too? On what grounds?

If it keeps the client happy, you could always artifically increase the duration of one of the parallel critcal activities each time they diverge, to get back to 1 critical path. Make the extra duration part of your TRA (Time risk allowance). A bit non-sensical to have to rig a programme to satisfy the client that it hasn't been rigged, but there you go.

Cheers,

G

I suggest incresing duration by a wooping one minute.

Hi Chris

LAD = Liquidated and Ascertained Damages.

What you have described on multiple critical paths could not happen if FS links were used.

Where you have SS links then the phenomenon of pararllel criticality will develop along a single critical path.

You have to ask yourself why the tasks are of the same duration - as Gary suggested if you shorten one by half an hour the "problem" will disapear.

The second part of your query is the NEC requirement for Time Risk buffers for both the Contractor's use and the Employer's.

They should both lie on the critical path but consecutively not concurrently between work completion and the contract completion date.

Best regards

Mike Testro

Hi Rafael

I have seen that happen so as to distort the critical path.

Another trick is to put a different work pattern of a work day of 7 hrs 59 minutes on selected tasks - I have even known planners to use two calendars with the same name but different work patterns.

In fact I wrote an article for Building Magazine titled The Games Planners Play but they declined to publish.

Best regards

Mike Testro

Mike,

About Garry's solution I find it a pragmatic approach when you know the other side is stubborn. 

Even some forensic annalists call for consideration of near paths as part of critical path analysis and many reject the theory of dominant critical path with regard to pacing versus concurrency. One minute making a critical path dominant!

Definitively calendars might be the preferred choice for manipulating schedules especially when your software is poor at exposing calendar manipulations as your beloved P6 is. Spider does not have such weakness with regard to calendars, but not everything is easy to discover, no matter what software you use.

Share your writing here, knowing about the possible schedule manipulations is on the best interest of all. Let us all agree or disagree with your points.  I would expand the discussion to include flaws in CPM analysis as manipulations I consider to mean performed with knowledge [intention] and malice.

Best Regards,

Rafael

Thanks Mike, Gary & Rafael.

Useful to know how others get around difficult situations. The client hadn't referenced the specific contract reasons, just that the programme wasn't showing what they wanted - I've sinced pointed this out to them, and explained how the programme works in detail which they seemed to be happy with (at the moment).

Chris.

Hi Chris

Negotiation is always the best way to solve a problem.

Just keep in mind the 4 grounds on which an Employer can reject your programme and make sure that they are adhered to.

Best regards

Mike Testro