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Top-Down Backlog Calculation

A method of calculating the backlog of deferred maintenance (ie., the backlog level) at a facility, sometimes for the purpose of deriving a Facility Condition Index (FCI) or, more realistically, a Preliminary FCI.

This method relies primarily on a mathematical calculation of consumed life for each asset to determine the value of the catch-up costs  to place in the numerator of the FCI formula.


Attributes

It does not generate a line-item aggregation of each identified deficiency (which is a bottom-up method).

The top-down method is primarily a  life cycle modeling method, which requires less field work – it is therefore generally preferred by capital planning software vendors who are focused on populating their software product. 


Evaluation
Some of the advantages of this method are identified as follows:

  • Rapid data analysis for a rapid assessment.
  • Cheaper cost than the bottom-up method.
  • Provides a level-1 screening to enable the owner to consider whether to proceed to level-2. See: mixed scanning.

Some of the limitations of the top-down method are identified as follows: 

  • The backlog may be grossly overestimated, particularly in situations where asset are still performing adequately beyond their typical service life;.
  • The method relies heavily on assumptions regarding Typical Service Life and ignores that some assets are right modal and have lives that extend well beyond the median life.  
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Fig. The use of software algorithms to compute backlog based on industry service lives and chronological ages.

Facility Condition Index FCI formula
Fig. The three formulas and key performance indicators (KPI) used to measure and evaluate the physical health of a facility.

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