Preventive Maintenance Intervals for Transit Buses (2010)

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5PROJECT BACKGROUND AND OBJECTIVES Preventive maintenance (PM) measures are performed at rel- atively fixed intervals throughout the transit bus industry. In some cases the intervals and related PM activities are based on legal requirements, the agency’s operating environment and experiences, and specifications provided by equipment manu- facturers. There is also anecdotal evidence suggesting that in some instances, the interval was simply borrowed from a peer organization with little or no other basis than “if it worked there, it should work here.” This survey of current practice determines just how PM intervals and activities are established at different agencies, understanding that each has different fleet makeup, operat- ing environment, and maintenance philosophy. Information obtained through this study is used to establish: • How transit agencies identify PM intervals and activities; • Common PM intervals used in transit, notable variations, and the rationale for both; • Experience level of the staff performing different PM activities; • Repair policies for defects identified during PM inspections; • Quality assurance (QA) measures placed on PM activities; • Particular components or systems that may benefit from a special PM interval; • The role of daily service line functions in PM; • How PM intervals relate to spare ratio and useful life; • How PM programs relate to road call experience and bus availability; • Allocation of parts and labor costs for PM; • Software programs that facilitate the PM process; and • Tools for predicting parts failures. This study is intended as a primer on transit bus PM for use by maintenance managers and other interested agency personnel, officials of state and metropolitan transportation and planning agencies, and university educators and students. In particular, bus maintenance personnel will be able to compare their PM program with others, learn from peers, and implement new procedures as proactive measures to help anticipate and prevent mechanical breakdowns instead of merely reacting to them. In 2007, there were more than 425,000 transit bus mechanical failures that resulted in rev- enue service interruptions in the United States (1). Although breakdowns can never be fully eliminated, measures taken by transit agencies to improve their PM program as a result of information obtained from others will help lessen the num- ber of inconvenienced passengers and the potential for safety- related incidents. TECHNICAL APPROACH The approach to this synthesis included a literature review, a survey of transit agencies, and telephone interviews with three agencies selected as case studies. A Transportation Research Information Services (TRIS) search using several different keywords was conducted to aid the literature review. The survey questionnaire was designed to elicit PM sta- tistics directly from those responsible for transit bus main- tenance. Once the survey questionnaire was finalized with input from the oversight panel it was posted on the Bus Fleet Maintenance listserve managed by the University of South Florida, Center for Urban Transportation Research. Of the 38 U.S. and Canadian agencies that volunteered to participate, all completed the survey for a 100% response rate. Table 1 shows the distribution of responding agencies by fleet size. Agencies that responded to the survey operate a combined fleet of just over 12,000 buses traveling more than 503 million miles annually. The propulsion makeup of the average bus fleet is 78% diesel, 14% compressed natural gas (CNG), 4% electric-hybrid, 2% gasoline, and 2% electric trolley. The Fleet Profile of all participating agencies is attached as Appendix A, sorted by fleet size, fleet makeup in terms of bus propulsion type, and fleet mileage. A copy of the survey questionnaire with summarized responses is attached as Appendix B. The sample is not random; therefore, although it is diverse in terms of size and geography, there is no guarantee that it is representative. REPORT ORGANIZATION Following this introductory chapter, chapter two summarizes the findings of the literature review and presents the PM clas- sifications used in this study, which also serves to review the subject of PM. Chapter three, the first of two chapters to pre- sent survey findings, examines the state of the practice with a focus on PM intervals, including how agencies establish and CHAPTER ONE INTRODUCTION

schedule those intervals, common PM intervals used, and procedures for determining when parts need to be replaced. Chapter three also examines factors that most influence the setting of PM intervals such as manufacturer specifications and the agency’s own experiences based on data collection and analysis, environmental and operating conditions, and fleet make-up. Chapter four looks at specific PM inspection, repair, and overhaul activities that take place at scheduled intervals. This 6 chapter also examines checklists and other tools used to guide PM activities, manpower and bus spare ratio considerations, QA measures, PM cost calculations, and how agencies go about repairing defects identified during PM inspections. Chapter five consists of three case studies that examine defined aspects of PM. Included are: • A technician certification program developed by the Whatcom Transportation Authority in Washington State to improve the quality of PM. • An automated onboard system in use by the Washington Metropolitan Area Transit Authority (WMATA) that automatically downloads vehicle health data as the bus enters the service line by means of wireless communica- tion, and actually provides verbal instructions to main- tenance personnel regarding vehicle faults that need immediate attention. • The PM approach used by the Central New York Regional Transportation Authority (Centro) to deal with its wide variety of bus types and various PM classifica- tions it has created to address fleet diversity. The report ends with conclusions, lessons learned, and suggested areas of future study (chapter six). No. of Buses in Fleet No. of Agencies Responding % of Agencies Responding 1–50 7 18 51–100 6 16 101–200 6 16 201–300 5 13 301–500 6 16 500+ 8 21 Total 38 100 TABLE 1 TRANSIT AGENCY BY SIZE