Reliability Centered Maintenance
Several of the principles described in this section are based on a Reliability Centered Maintenance (RCM) approach, a technique that is sometimes used by an agency to identify the most appropriate management method. Looking at an asset or asset class from an RCM perspective helps to select a management approach based on safety, operational and economic criteria. RCM is commonly applied to complicated assets that may require a range of management approaches for different components of the asset.
The RCM process has its roots in the aviation industry related to the mechanical components of aircrafts, but has been adopted across multiple industries for mechanical, electrical and infrastructure assets. Within the highways industry RCM has been considered for ITS assets. More information on the use of RCM for ITS assets has been published by Austroads (2016): Reliability-centered Maintenance Strategy and Framework for Management of Intelligent Transport System Assets.
RCM considers seven fundamental questions to select the most appropriate management approach for a set or type of assets (SAE International 2009). These questions can be applied to the selection of life cycle management approach. Based on the responses to these questions, an agency can determine what maintenance approach, for which parts of the asset, will maximize the likelihood of an asset performing its desired function for the lowest practicable cost. These questions are as follows:
- What is the item supposed to do and what are its associated performance standards?
- In what way can the asset fail to provide the required functions?
- What are the events that cause each failure?
- What happens when each failure occurs?
- In what way does each failure matter?
- What systematic task can be performed proactively to prevent or diminish to a satisfactory degree the consequences of the failure?
- What must be done if a suitable preventive task cannot be found?
RCM can be presented in a decision tree to aid agencies in selecting the best management approach. Agencies can also customize the questions and decision tree to meet their specific need. Figure 4.7 represents a portion of a decision tree customized to select the appropriate management approach for ancillary highway assets. By applying these questions to an asset class, an agency can prioritize asset classes for monitoring and active management. An agency can also determine which assets present limited risks to system performance and can be managed through less expensive means.