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Page 84
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2018. Optimal Replacement Cycles of Highway Operations Equipment. Washington, DC: The National Academies Press. doi: 10.17226/25036.

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84 Glossary Condition score—The score assigned to a vehicle compo- nent as part of the condition assessment process. Depreciation—An equipment unit’s loss in capital value measured as the original purchase price less the salvage value. Downtime—The hours that an equipment unit is out of service during normal working hours. Equipment age—The age of an equipment unit, measured in years from the current date to the in-service year. Equipment class—A grouping of equipment units of similar size and functionality, normally accompanied by a unique class code. Equipment utilization—The hours or miles that an equipment unit is operated, typically measured by annual utilization or life-to-date utilization. Inflation rate—The annual inflation rate used to normalize equipment costs to constant dollars and to project future equipment replacement costs. Life Cycle Cost Analysis (LCCA)—An economic model for analyzing equipment costs. Class-level LCCA—Used for determining optimal life cycles; applied to all equipment units with a specific class. Unit-level LCCA—Used for analyzing individual equip- ment units. Maintenance and repair cost (M&R)—The cost for main- taining, servicing, and repairing equipment units includes all types of repairs. Mission criticality—A rating assigned to equipment units to recognize the relative importance of individual units and used to help rank replacement priorities. Obsolescence cost—The cost associated with the reduced performance and efficiency of equipment over time. Operating cost—The cost of maintenance, repairs, and fuel of an equipment unit and expressed in cost per mile/hour for LCCA. Optimization tool—The Excel-based tool for performing LCCA and providing analysis to support the replacement process. Ownership cost—The capital investment cost of equipment; expressed in cost per mile/hour for LCCA. Overhead rate—A percentage factor applied to mechanic labor to account for mechanic and shop overhead costs. Direct overhead—Overhead associated directly with mechanic labor. Indirect overhead—Overhead associated with shop opera- tions for maintenance and repairs. Replacement cost—The current cost to replace an equipment unit with a like unit. Replacement planning values—Target values for age and uti- lization, used to identify potential replacement candidates. Salvage value—The resale value of a unit that can be expressed as a percent of the original purchase price. Shop work order—A paper or computerized form for cap- turing labor hours, costs, and other pertinent information for a single equipment repair event. Unit—An individual piece of equipment.

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TRB's National Cooperative Highway Research Program (NCHRP) Research Report 879: Optimal Replacement Cycles of Highway Operations Equipment acts as a handbook on equipment replacement concepts and an instruction manual for making cost-effective replacement decisions. The research report presents a process for determining replacement needs for highway operations equipment, identifying candidate equipment units for replacement, and preparing an annual equipment replacement program. The products include a guidance document and an Excel-based replacement optimization tool to support the equipment replacement process and facilitate its implementation.

Disclaimer - This software is offered as is, without warranty or promise of support of any kind either expressed or implied. Under no circumstance will the National Academy of Sciences, Engineering, and Medicine or the Transportation Research Board (collectively "TRB") be liable for any loss or damage caused by the installation or operation of this product. TRB makes no representation or warranty of any kind, expressed or implied, in fact or in law, including without limitation, the warranty of merchantability or the warranty of fitness for a particular purpose, and shall not in any case be liable for any consequential or special damages.

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