The Mantua Group

Simple Black and White Asset Management, Reliability Expertise, and Maintenance Execution Perfection.

Risk

Competing Risks, Or Not?

Disciplined Failure-Mode Decomposition for Reliability Data Analysis: When the Risks Framework Applies, When it Misleads, and the Practical Questions That Tell the Difference

The decision to model failure mechanisms as competing risks or to treat them as independent processes requiring separate analyses is among the most consequential a reliability engineer makes. The choice cannot be settled by software, by professional habit, or by the convenience of an aggregated dataset. It can be settled only by a clear understanding of the physics of failure, the timing of risks exposure, and the empirical evidence that two or more mechanisms genuinely overlap on the timeline of an asset’s service life. This white paper sets out the discipline that distinguishes legitimate failure mode competing-risks modelling from analytically convenient over-aggregation, the framework that follows from each choice, and the practical questions a practitioner should pose before adopting either approach.

Cost-Optimized Inspection Intervals for Transmission Structures

Balancing Inspection Costs Against Failure Consequences Using Risk-Based Optimization Methods

This white paper presents a cost-optimization methodology for determining inspection intervals for transmission line wood pole structures. The approach balances three competing economic factors: inspection costs, planned replacement costs, and unplanned failure consequences—to identify the inspection frequency that minimizes total cost of ownership while maintaining acceptable reliability levels.

Rather than applying uniform inspection schedules across all structures, the methodology calculates individually tailored inspection intervals based on each structure’s age, probability of failure, and consequence of failure. Results typically range
from 6-month intervals for high-risk aged structures to 10-year intervals for low-risk newer assets, with most transmission lines optimizing between 1.5 and 4 years.

Implementation produces measurable cost savings by concentrating inspection resources on structures that provide the greatest risk-reduction value, while avoiding unnecessary inspections of assets with negligible near-term failure
probability.