What does this mean? "explain the exposed and hidden (patent and latent) contingency in the schedule.

What does this mean? "explain the exposed and hidden (patent and latent) contingency in the schedule.

A related odd question is "Does the Basis of Schedule indicate what percent of each activity's duration contains build-in "patent contingency?"  - I googled it - nothing comes up.

Planning, Scheduling & Programming Discussion
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Rafael Davila 👤 Member for 22 years 3 months
· Permalink

The best way to disclose and explain why the difference in activity durations is by disclosing volume of work and crew production rates. 

Buffer-Management-Productivities

Experienced schedule reviewers will always question how activity durations are calculated to validate the schedule and reduce activity duration padding, a principal culprit of float sequestration.  

Modeling of seasonal adverse weather shall be explicit and dynamic: crew selection and crew production rates shall be a function of the season, if an activity or part of it is delayed the model shall adjust durations considering the changes in production rates. Doing this by hand can become a monumental task when changes in durations move other activities that are linked by logic as well as by resource leveling. It is not good enough to consider adverse weather days only and not consider the impact of the season on the work days.

Productivity-reduction-impact-on-duration more dramatic impacts are not unusual, in winter in places where it do not snow cold weather may not stop work but different crew/equipment and shorter workdays may mean a substantial reduction in crew production rate and increased activity duration.

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Zoltan Palffy 👤 Member for 16 years 10 months
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The first part "explain the exposed and hidden (patent and latent) contingency in the schedule. They want you to tell them if you have padded any durations (from the normal industry rates of installation) or if you have consiered adverse weather into your schedule. Have you considered a less than optimum resources due to covid ? 

The next part  "Does the Basis of Schedule indicate what percent of each activity's duration contains build-in "patent contingency?". This means did you use a percentage multiplier for certain types of activities. For instance maybe for the outside work during the cold weather months you multiplied your original duration that would have originally been done in warm weather by a certain percentage. Another example is if you are doing work 20 ft in the air instread of 8 ft in air. In other words have you used a performance FACTOR (thus increasing the durations from their normal durations by a certain percentage) for any activities ? If so what type of activities have you used it on and what performance factor did you use ?

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Rafael Davila 👤 Member for 22 years 3 months
· Permalink
  • By creating two versions, one without buffers (optimistic) and another with the buffers (target) you can show and quantify your buffers. You aim for the optimistic in the hope you will meet the target. This is a simple approach that do not requires probabilistic modeling.
  • Terminal float: Under NEC 3 contracts the period between planned completion and completion date is owned by the contractor under the contract. NEC 3 requires all submitted schedules to show reasonable terminal float and any schedule lacking terminal float might be rejected as targeting for a schedule with no float is considered bad practice as this means 50% of the time you will not make it.You can show terminal float as a hammock while showing float based on Planned Completion Milestones as shown in this sample schedule. a) Fix Contract Completion Milestone using start and finish constraints equal to the contract completion date and set it to not consider in scheduling. Do not fix this milestone using activity links. b) Apply contract finish date to Planned Completion Milestone.
  • Good Luck
  • Simple-Buffer-Management
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Tom Boyle 👤 Member for 19 years 6 months
· Permalink
John,
To me, these clauses ask you to describe how you have accounted (explicitly and implicitly) for schedule risks.  
 
 
"Patent contingency" comprises explicit schedule buffers - whether distributed among activities as defined time risk allowances (see NEC contracts) or consolidated in one or more specific buffer activities - typically assigned to guard key milestones (see AACE recommended practice).
 
  
"Latent contingency" is the obvious opposite.  The spec writer wants you to go on record either confessing or denying that you have padded durations or imposed preferential logic to delay the forecast project completion date beyond the minimum/reasonable/expected value.  That last bit is vague enough that there's really no right answer. 
 
 
(I agree that "patent" is a rare word in this context.  I imagine it's only used here to contrast with the more common "latent".) 
J
John Reeves 👤 Member for 13 years
· Permalink

The adjective meaning of patent is "easily recognizable; obvious".  - who would use that word - a Laywer, the British? - seems weird.

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