Condition-Based Maintenance
Executive Summary
Key Takeaways
- ✓ Condition-based maintenance schedules intervention from an asset's actual measured condition, rather than a fixed age or calendar-based interval, requiring an ongoing inspection or monitoring programme.
- ✓ It sits between reactive maintenance (responding only after failure) and purely age-based preventive maintenance, generally producing better-timed intervention than either extreme when properly resourced.
- ✓ Condition-based maintenance requires reliable, current inspection data — a programme with infrequent or low-quality inspection data effectively degrades toward age-based maintenance regardless of its stated methodology.
- ✓ It is the practical data source underlying a condition-based remaining useful life estimate, and by extension, condition-based renewal timing in an asset renewal model.
Definition¶
Condition-based maintenance schedules intervention, maintenance, refurbishment, or renewal, from an asset or component's actual measured condition, obtained through inspection or monitoring, rather than from a fixed age or calendar-based interval.
Where It Sits Between Reactive and Age-Based Maintenance¶
Reactive maintenance responds only once a failure has already occurred. Age-based (preventive) maintenance intervenes on a fixed schedule regardless of the asset's actual condition at that point. Condition-based maintenance instead times intervention to the asset's real measured state, generally producing better-targeted maintenance timing than either extreme, since it avoids both the unplanned cost of reactive failure and the potential waste of intervening on an asset that is still in good condition under a rigid age-based schedule.
Data Requirements¶
Condition-based maintenance depends entirely on reliable, current inspection or monitoring data. A programme that performs inspections infrequently, or with inconsistent quality, effectively degrades toward age-based maintenance in practice — the methodology may be labelled condition-based, but if the underlying data is stale, the actual intervention timing is no more informed than a fixed schedule would produce.
Relationship to Remaining Useful Life¶
Condition-based maintenance is the practical data source that makes a condition-based remaining useful life estimate possible. Without an active inspection or monitoring programme, RUL estimation falls back to age-based assumptions, which is a materially less accurate basis for the renewal timing used in an asset renewal model.
Common Errors¶
- Labelling a maintenance programme condition-based while relying on infrequent or outdated inspection data.
- Applying condition-based maintenance to some asset types but not others in the same portfolio, without disclosing which assets remain on an age-based basis.
- Failing to feed condition assessment results back into the asset register in a timely manner, weakening every downstream model that depends on register data.
Continue Reading¶
Prerequisites¶
- Infrastructure Asset Management Financial Modelling — the parent pillar
Related Technical Guides¶
Related Glossary¶
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Frequently Asked Questions
What is condition-based maintenance?
A maintenance approach that schedules intervention, maintenance, refurbishment, or renewal, from an asset or component's actual measured condition, obtained through inspection or monitoring, rather than from a fixed age or calendar-based interval.
How does condition-based maintenance differ from reactive and age-based maintenance?
Reactive maintenance responds only after failure occurs. Age-based (preventive) maintenance intervenes on a fixed schedule regardless of actual condition. Condition-based maintenance sits between the two, timing intervention to the asset's actual measured state rather than either failure or a calendar date.
What does condition-based maintenance require to function well?
Reliable, current inspection or monitoring data. A programme with infrequent or low-quality inspection data effectively degrades toward age-based maintenance in practice, regardless of its stated methodology, since stale data cannot actually reflect the asset's real current condition.
How does condition-based maintenance relate to remaining useful life?
It is the practical data source underlying a condition-based remaining useful life estimate — RUL calculated from actual condition data, rather than age alone, depends directly on an active condition-based maintenance and inspection programme being in place.
Related Articles
Remaining Useful Life (RUL)
Remaining useful life (RUL) is the estimated period, expressed in years, that an asset or component can continue to perform its intended function at an acceptable standard before renewal, major refurbishment, or replacement becomes necessary. It is distinct from an asset's total or theoretical design life, since RUL reflects the asset's actual current condition and usage history rather than a fixed assumption made at the point of original construction.
Maintenance Cost Models
Maintenance cost modelling for an infrastructure asset or portfolio forecasts routine (day-to-day) and major (periodic, large-scale) maintenance spend from asset condition and criticality data, structures the reactive-versus-planned maintenance mix, and connects major maintenance cost to its reserve funding mechanism. This guide covers general infrastructure maintenance cost modelling — buildings, transport assets, utility networks, and similar physical infrastructure — distinct from the power project O&M contract mechanics covered in Operations and Maintenance (O&M) Cost Models.
Asset Renewal Models
An asset renewal model forecasts when each major component of an infrastructure asset will need replacement or major refurbishment, sizes the cost of that renewal event, and connects it to the reserve funding mechanism that pays for it. This guide covers how to build a renewal model: age-based versus condition-based renewal timing, the renewal cost curve across a portfolio, and how renewal funding and drawdown mechanics should be structured, extending the general reserve treatment already established for project finance maintenance reserve accounts.
Asset Register
An asset register is the structured inventory of an owner's infrastructure assets, recording each asset's identity, location, original cost, installation date, condition, and criticality, among other attributes. It is the foundational data source from which asset management plans, whole-life cost models, and renewal forecasts are all built, and its completeness and accuracy directly determine the reliability of every downstream financial model that depends on it.