Schedule Logic

Hi Ahmet

Not every construction programme has a critical path to completion.

There are projects that have discrete sections of work with no logic between them - most sub-contract programmes fall into this category.

Others such as cable replacement on rail works have no critical path.

I recently worked on a fibre optic cable installation in an airport terminal which had no critical path.

Best regards

Mike Testro

Well all activities except the very last one, musr hace successors for a working ng single critical path. No? So first he should corrrect that. Then I didn't understand what you mean by longest path has only one activity

Vladimir,

Thanks a lot, I was missing the part on setting the e-mail, can be to my own, very easy indeed. Reminds me of a similar but not automatic Mail function that was available in SureTrak and P3. 

Best Regards,

Rafael

Rafael,

you wrote "the part I am not versed is on detaching the project/subprojects for the contractors/subcontractors update the schedule".

In Spider Project it is Distribute and Consolidate subprojects. Just set who is responsible for the subprojects and where to send their subproject files. For this list Responsible persons and their folders in the Users table and assign certain Managers at Phase (subproject) properties. Very easy.

Regards,

Vladimir

Mike,

Regarding idea of a sub programme for subbies - how do you cross link between the sub programmes.

• If using Subprojects you make the links on the job file that will include all subprojects. 
• If using Portfolios you make the links on your portfolio file with all related jobs open.

This is the easy part, the part I am not versed is on detaching the project/subprojects for the contractors/subcontractors update the schedule. Here I use old worksheet method. 

Even during the few years I used P3 I never used Project Groups, the jobs I got involved were relativelly small jobs, in the order of 10 to 20M$, pampers league but with all sort of resource issues as if larger jobs, except perhaps financial constraints that mostly are mostly seen at the client portfolio level. Obviously you create a group on major subcontracts only. 

I am sure Asta provides a good interface for updating purposes but with their own peculiarities, it even has a time card module but wonder how it is integrated with payroll systems. Needles to say I consider Asta PP and Spider Project much better than P6. 

http://www.datcc.pl/files/asta_powerproject_en.pdf

Best Regards,

Rafael

Hi Rafael

The purpose of named milestones is locate the logic from a level 5 s/c programme into a level 3 m/c programme. Once the logic is connected they can be deleted using the delete and relink facility.

Regarding idea of a sub programme for subbies - how do you cross link between the sub programmes.

Best regards

Mike Testro

This is why the meeting with the subcontractor is needed as suggested before, from the very beginning by Gary.

In such meeting reason for all date constraints will follow, some may be because of missing logic, even late date constraints because of missing successors. Do not assume there is nothing wrong or right with the subcontractor schedule, not all subcontractors are saints and some will try to sequester some float for the same reasons some general contractors do. 

You might find some activities with a subcontractor predecessor/successor , can also still be missing links to GC and/or other subcontractors activities.

When working with multiple subcontracts it is customary to subdivide the job into separate jobs and perhaps into separate subproject if the software provide for both options. Mainly it is because of convenience for updating that this is done. It will allow you to detach subproject or project from a portfolio so that the subcontractor himself updates the schedule progress and submit it to you for your review and further incorporation on the updated project.

I prefer for subcontractors to use subproject on big jobs and on smaller to integrate schedule without using subprojects. Subproject is an option available in Spider Project where a portfolio consists of several projects and each project might have several subprojects. Because of the small size of my jobs, usually around 600 activities I am not versed with the use of Subprojects. It is not a new idea and even old P3 executed the subproject approach using what they called project groups but lacked the portfolio approach unless modeled as a huge group within P3 limits on number of activities per job. 

I do not favor adding unnecessary milestones that can create problems; they must be updated by someone who must take updating action and if wrongly updated the manager of successor activities might argue he was waiting for your instructions instead of following schedule logic. They add unnecessary burden at the time of updating the schedule; in some cases it is difficult to identify driving predecessor prior to some schedule update calculations and it might be update date be wrongly assumed creating unnecessary out-of-sequence issues that can be questioned latter. 

Hi Harold

A subcontract programme has to be slotted into a Main Contractor's overall programme.

Sub contractor tasks start when the preceding subcontractor vacates the location.

the Subcontractor hands over to the next trade when his work is complete.

If the Sub contractor has not been given precise start inteface dates then he can only guess and the only way to set the interface start dates is to use Must Start On constraints.

The completion date is left with open ended tasks because there is no succeeding task to link it to.

That is the job of the Main Contractor's planner - presumably you - and you have to combine a SC level 5 programme into what is presumably a level 3 or 4 document. Good luck.

I would prefer to see the S/C start and end interfaces added to named milestones to make the transfer into the Main Programme much easier.

So there is not much wrong with the sub contract programme you have recieved but you should ask the subbie to present it differently with take over and hand over milestones clearly shown.

This format will also assist the "Permission to Work" regime that you need to control progress.

Best regards

Mike T.

Are all date constraint of the finish not latter than type?

Are some of the mandatory start/finish type?

Finish no latter than type constraint can be used as a float suppression strategy. 

Though I believe some float shall be protected it shall be minimum and transparent. I do favor buffer at the end of the network; the critical chain can vary as soon as the schedule is updated, this might mean some feeding buffers will be out of place.

I also advocate for proper use of lag but same as imposed dates they can be used as float suppression strategy. I add this to the requirement for each lag value be justified.  Some specifiers require it to be not more than a certain % of predecessor duration, others limit it to a fixed value such as a week, and if this requirement is not met then they shall be justified. 

Some open ended activities can make sense, but very rare. A warranty or something like landscape maintenance might be one such activity. 

Not all software calculate backward pass on activities constrained with finish no latter than constraint. Spider project default method makes the activity critical with 0 float when the constraint is not enforceable but also provides the traditional negative float calculation [I never use except to make it available upon request]. 

Another way to sequester float not well documented is by adding artificial non-work days to calendars, not only at baseline but on a subsequent update where it is difficult to detect for most software. 

I must agree 100% with Gary in his approach. 

If this schedule only cover a single subcontractor work maybe some substantial investigation is still needed as to evaluate the links and resource sharing to work by other subcontractors, general contractor and perhaps to other jobs in your portfolio.

Because subcontractor cannot link by himself activities to main schedule he might be using some constraints in lieu of such links. This is another reason why I agree so much with Gary's approach. 

Harold,

Rather than outright rejection, I would require written justification for each constraint, and reject/approve on that basis. -There are valid reasons for using constraints (eg client to provide permanent power might be a milestone with SNET constraint), and rejecting without understanding why the constraints are there is a bit harsh imo.

No excuse for open-ended activities. I would insist all these are correctly llinked.

I personally don't like to see contractual milestones constrained as it screws with the float calcs, but I get why others do. If they are retained, you have no guarantee of a proper longest path, so I would include within your review an excercise of (temporarily) removing all constraints and checking the unconstrained longest path.

Cheers,

G