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1.9 Concept of reliability-centered maintenance
failure and its consequences. A good example is a risk-based asset management plan adopted by the Colorado Department of Transport (Colorado DOT 2019). RBM, which is often supported by software analytic applications, is useful for managing assets that carry a high risk of failure with substantial negative technical, social, environmental, or financial consequences (for example, bridges, water mains, treatment plants, or metrorail systems). RBM analysis signals the need to maintain such assets or specific parts that should have high priority over other assets that have a low risk of failure or low level of negative consequences.
Reliability-centered maintenance. Despite strong consequences of excessive reliance on reactive maintenance, it would be inappropriate to overemphasize preventive maintenance for several reasons: (1) reactive maintenance will remain a significant activity in addition to preventive maintenance, because the urban service systems are big and complex, and unexpected and unpredictable failures will happen time and again; (2) preventive maintenance requires sophisticated AM and analytic capacities, some expensive; and (3) the various components of a complex plant or network bear various levels of failure risk and various levels of consequences. The concept of reliability-centered maintenance aims to reduce the costs while providing a high level of system functionality and reliance by introducing four maintenance options based on asset specificities (figure 1.9).
Reliability-centered maintenance approaches maintenance in a spectrum of activities (figure 1.9). One of these is solely reactive maintenance, which, however, is advisable only for small, noncritical items or items unlikely to fail (Pride 2016). In the figure, the steps upward depict variants of preventive maintenance that increasingly require more sophisticated data and analysis. The simplest is interval-based preventive maintenance applied without detailed analysis of the assets, such as resurfacing a highway every 15 years. Equipment producers often advise using time-based replacement plans, too. Time-based maintenance works most of the time; but the manner of operation and unknown internal conditions could make an asset or equipment more reliable or less reliable than producers
FIGURE 1.9
Concept of reliability-centered maintenance
Reactive
Small items, noncritical, inconsequential, unlikely to fail, redundant Interval-based preventive
Subject to wear out, consumable replacement, failure pattern known Condition-based preventive
Random failure pattern, not subject to wear, preventive, maintenanceinduced failures Proactive
Root-cause failure analysis, age exploration, failure models and effects analysis, acceptance testing
describe, so experts may rightly overwrite the time-based maintenance plan based on technical checks (for example, kilometer run of a truck).
Condition-based preventive maintenance requires an expert check of infrastructure systems, subsystems, or equipment without detailed and sophisticated analysis. Condition checking requires performance indicators, many provided by producers of the assets, and experts to inform decisions on time and nature of repair actions. Finally, root-cause failure analysis requires sophisticated data collection and complex evaluation methodology; local governments rarely own the expensive assets needed to use this method.
Operation and maintenance. There is no sharp dividing line between operation and maintenance since O&M actions are intertwined both in time and functionally. O&M is a popular acronym in reports of public entities. However, it has three different meanings or contexts. First, in financial terms, O&M is a budget line item that reflects the total amount of money spent in a year on all kinds of expenses that are parts of O&M. This figure, however, is too synthetic and shows only O&M expenses against administration, development, or transfers to subordinated entities; it fails to show the amount spent on repair and maintenance. Second, O&M can combine all expenditures spent for provision of a service, including details of labor, material, energy, and repair and maintenance. In this context, O&M helps cost accounting and cost control of services by forming cost centers, which help measure service performance in financial terms by comparing O&M expenditures with revenues collected from the same services.
Third, O&M also covers the combined technical activities of operating and managing assets; these include detailed procedures, rules, and decisions for corrective measures (repair or refurbishment). Appendix E includes excerpts from the O&M procedures that the US Environmental Protection Agency (EPA 2015) advises be performed in operating and maintaining water service systems to prevent environmental damage from improper O&M. This guidance, from an O&M manual (EPA 2012), advises sets of actions to be performed daily, monthly, quarterly, and annually. Similar O&M manuals exist for all main forms of assets such as buildings, water and sewage, or road O&M. Many of them are unknown or poorly followed in developing countries.
Annual repair and maintenance plans. Besides the medium-term capital acquisition plans, the departments and sectors that hold high-value assets and infrastructure should adopt annual repair and maintenance plans following the principles of preventive maintenance practices. These maintenance plans should be financed after approval with adequate funds appropriated in budgets for both planned and reactive maintenance. Unplanned reactive maintenance and repair of unexpected breakdowns are inevitable parts of regular AM, although those remain smaller expenses if preventive maintenance is well instituted and implemented. Departments and sectors also should set aside funds for unplanned reactive repair and maintenance in annual maintenance plans.
Annual plan and report for deferred maintenance. The annual maintenance plans should include a section that summarizes the plans for deferring maintenance due to a shortage of funds. But deferrals should not be kept secret. They should be well recorded in both the maintenance plans and the technical asset registers and reported to higher governing bodies such as the AM directorate, some even to the assembly, the county executive committee, the county secretary, and the deputy governor and governor.
Accounting-oriented AM, that is, accounting, registering, and reporting, is a specific aspect of AM that is largely the responsibility of the chief accounting officer and the AM department that maintains the central asset register, based partly on data received from service departments and technical asset registers. The accounting registers reflect historic values (also called book values) and depreciations and furnish balance sheets with aggregate figures of these value terms such as net value of fixed assets (historic value minus depreciation).
Income-generating and investment properties require special attention, some even a special account, and strategic management. The AMDR should establish specialized real estate expertise and supplementary registers especially for dealing with income-generating and investment properties. Investment properties, those in joint ventures, and/or those managed daily by legally independent entities do not fit into the fixed asset register since they are financial assets; still, managing them requires special attention to ensure adequate revenue generation.
To strategically manage these assets, the AMDR would need to undertake special targeted valuation of all income-generating and investment properties in the context of strategic management of the entire asset portfolio. Furthermore, any major strategic asset decisions such as planned divestiture, leasing, or moving assets to joint ventures should factor in updated market values of property. These valuations also are needed for annual assessment of the profitability of leased or other income-generating properties (for example, to estimate return on investment) and other periodic economic analyses to compare investment or divestiture alternatives (Detter and Fölster 2018).
The central asset register is the core accounting database for strategic AM, to be established and maintained by the AMDR or team. Strategic AM, as noted, has important links to the master plan, spatial development plans, and the capital investment plans, since SGAM decisions should be in harmony with those plans. There are good off-the-shelf ICT modules available to support various aspects of LCAM, from planning to risk analysis, many specialized to specific clusters of services or assets (water, transport, buildings, and so forth).
Income-generating properties. For income-generating or investment property operation, securing comparably adequate revenue flows from rental and lease income should be linked to LCAM to ensure the assets perform adequately, primarily in financial terms but also in technical terms. Analysis of financial performance of assets is a vital part of good AM (as figure 1.2 depicts). Market benchmarks of revenues should be set and verified annually or biannually to monitor financial performance. For instance, a department responsible for building management that rents and manages housing, office, or commercial buildings should properly calculate and report to the central register not only the collected revenues but also the foregone revenues when assets are leased out at below-market prices to support charitable or socially important activities, or for legal reasons that impede regular increase of the lease or rental fee.
ICT system and tools
ICT tools are underlying instruments that support most aspects of AM. There is a rich market of software applications that support the life-cycle, technical, or accounting AM with easy-to-use registers and analytic tools. The availability of costless GIS programs with digitalized maps and global positioning system (GPS) tools has greatly improved both ICT realization and verification and
