Tuesday, 3 January 2017

My Settings #06: P6 Schedule Review

This post has long been overdue as I promised a follower of this blog in October 2016 that I would pen a post about steps I follow to review a Primavera P6 schedule. As always, these steps are non-prescriptive and have served me well when reviewing P6 schedules from contractors, subcontractors, colleagues and even my own P6 schedules.

The steps I follow are outlined below in no particular order.

Scope of Work (SoW)

Read the Project's SoW at least once so that you are very familiar with the SoW and know all the Project deliverables. Then summarise the SoW into a list of deliverables covering Project Management, Engineering, Procurement, Fabrication, Construction, Installation & Commissioning. This list is then used to check if the P6 schedule covers all the work packages outlined in the SoW, i.e. check if the schedule complies with the 100% rule (having a properly defined Project WBS helps).

Contract Document & Planning Procedure

Have a good understanding of the Project Coordination or Project Administration section of the Project Contract as well as the Planning Procedure governing the schedule as these documents usually outline the following:

  • scheduling logic settings (retained, override or actual dates)
  • critical path definition
  • resource loading requirement
  • fields to display in printed schedules
  • unit of duration
  • date format etc.

Ensure that the issued P6 schedule complies with both Project Contract and the Planning Procedure

P6 Schedule Log

Enable P6 schedule log (Tools > Schedule & tick Log to file checkbox). Review this log after a time analysis (by clicking View Log in the schedule dialog prompt) by keeping an eye on the following warning messages

  • Activities without predecessors (should not be more than 1)
  • Activities without successors (should not be more than 1)
  • Out-of-sequence activities (should be 0) - if you are using retained logic
  • Activities with Actual Dates > Data Date (should be 0)
  • Milestone Activities with invalid relationships (should be 0)
  • Activities with unsatisfied constraints (should be 0)
  • Activities with unsatisfied relationships (should be 0)



Also review the list of date constraints shown in the schedule log and ask yourself the following questions.

  • Are all the constraints valid
  • Are all these constraints defined in the Schedule Basis document

Valid constraints are usually contractual in nature or are external milestones or are driven by resource availability (assumes you are reviewing a task dependent schedule). High number of date constraints should ring alarm bells as most likely they are being used in place of schedule logic

Schedule Logic & Danglers

Have a good understanding of the logic relationships that exist between work packages and activities to ensure that the expected logic relationships are reflected in the schedule. Review the relationships between activities in the schedule using one of the following methods

  • Enable Activity Details Form and add the Relationships tab or
  • Export Activities Relationships to a Spreadsheet or
  • Generate a Predecessors Report 

Ensure that the Schedule Basis Document explains use of any SS, FF & SF logic relationships in the schedule. If not explained in the document, seek clarification and if in agreement with reasons given for the non-FS logic relationships, ensure these are added to the Schedule Basis Document (I still do not know the benefit of SF relationship and have never used it).

Also, using one of the methods above, look for dangling activities i.e. where an activity predecessor or successor has only SS or FF relationships. There should be no danglers in the schedule as they affect total float calculations

Total Float

Review total float, a very high total float is a sign of open ends or poor logic relationships. I would normally investigate any total float more than 60 days (or 90 days depending on the overall project duration). Ensure that activities with high total floats have the right logic relationships (predecessors and successors) as wrong logic relationships impact on critical path, key milestone dates and forecast project finish date.

Lags

Filter for all activities with lag not equal to 0. If these lags are not explained in Schedule Basis document, ask for clarification and ensure you are in agreement with all lags used in the schedule and if possible they should be documented. Lags are invisible schedule influences and their use should be minimised, instead of lags, add activities to represent tasks where possible.

Durations

Review activity duration, large durations mask problems, so activities with large duration should be split into smaller duration, I normally restrict myself to a maximum of 30 days per activity. And from my experience, it is much more easier to build a more realistic schedule network with manageable activity durations. Also, it is easier to track and measure progress on activities with smaller durations.

Soft Logic

Review the schedule Basis Document and ensure it lists all Soft Logic links in the schedule and also documents the reasons for their use. P6 unlike Asta Project & Spider Project does not distinguish between Soft & Hard Logic links, so you need to know which relationships in the schedule are Soft Logic links so that these can be broken at any point during project if they start having undesired impact on a successor activity. Unlike Soft Logic links, Hard Logic links will always remain in place except where there has been a change in the basis for the logic.

Resource Assignment

If the issued schedule is resource loaded, review resource assignment to ensure the right resources have been assigned to activities and that each resource availability (from Schedule Basis Document) match assigned activities schedule. Also, review resource usage to ensure no resource is overloaded.

Final Word

That is all for today and I hope you have found this post useful. Do you follow any of the steps outlined above when reviewing a P6 schedule? Please share your own tips.

4 comments:

  1. Great work! Many thanks for this. I have been searching the net for detailed procedure to follow when reviewing contractor's schedule. I would only add that in addition to Schedule log which provides a basic but effective method of checking the quality of the schedule, Acumen fuse produces a much more in-depth view and quality check, allowing you to demonstrate the quality of the schedule.

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  2. Detailed and informative. Thanks once again for the tutorials.

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  3. Thanks for sharing, it's always good to know how others are doing the review and be able to pick up some good points along the way.

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  4. Thanks for publishing the easy and best tutorials. Keep it mate

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