Preventive Maintenance Intervals for Transit Buses (2010)

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25 INTRODUCTION This chapter reviews procedures used by agencies to carry out PM tasks such as use of inspection checklists and other tools that guide technicians through the PM process, labor alloca- tion in performing PM tasks, and PM costs in terms of parts and labor. Also examined are various QA measures taken by agencies along with the various approaches taken to repair defects noted during PMIs. Information provided in this chap- ter is based on material obtained from survey responses. CHECKLISTS AND OTHER GUIDANCE TOOLS Checklists Checklists provide a useful tool to help guide technicians through each PM activity. The checklist documents that activ- ities did take place on a certain bus at a given interval, which is helpful in satisfying inspection recordkeeping require- ments (49 CFR Section 396.21) established by the U.S.DOT. Unique checklists are pertinent to specific buses and related equipment. The opposite is a generic, less-effective checklist used for all bus types in the fleet regardless of equipment make or type. All responding agencies use some form of checklist to guide PM activities. Common checklists are those for bus inspections, HVAC inspections, and wheelchair lift and ramp inspections. Table 13 shows the percentages of responding agencies using a unique checklist to conduct common PMIs. Agencies reported using checklists for 20 individual PM categories, including the three listed in Table 13. Of those, 59% use checklists unique to specific equipment. Other PM areas where checklists are used include: – Charge air cooling PMI – Brake system PMI – Cooling system PMI – Farebox PMI – Radio system PMI – CNG tank PMI – Articulation joint PMI – Fire suppression system PMI – Transmission PMI – Electrical system PMI – Driver seat PM repair – Articulation joint PM repair – Farebox PM repair – Fire suppression system PM repair – Radio PM repair – Engine PM overhaul – Transmission PM overhaul. Centro, Syracuse, New York, has a fleet of just under 300 buses and uses 21 specialized PM classifications that cover different bus types, HVAC, wheelchair lifts, electrical system, fire suppression, and others. Additional information on Cen- tro’s PM program is included as a case study in chapter five. A good example of a unique bus PMI is provided by Cap- ital Metro Transportation Authority, Austin, Texas, devel- oped for Optima buses. The checklist begins with general instructions, continues with an explanation of terminology, defines conditions under which immediate repairs can be made, and provides work instructions. A section of that PMI is included as Appendix F. In addition to the checklist, Capital Metro includes what it calls “repetitive functions” sheets that itemize service, repair, and replacements that need to take place or be “repeated” at specific intervals for each bus type. For example, the agency replaces headlights at certain intervals regardless of their condition. For buses with a faulty idler pulley the repetitive sheet calls for a new design replacement. PM checklists and repetitive sheets are updated as new information becomes available. Capital Metro’s MIS sys- tem prints checklists and repetitive sheets just before each PMI to ensure technicians are provided with the most cur- rent information. Pass/Fail Criteria Inspection checklists also include specific pass/fail criteria to denote acceptable standards for equipment condition and performance. Of survey responders, 84% include some pass/ fail criteria for carrying out PMIs and repairs. Pass/fail crite- ria for brakes are mentioned by nearly all survey responders who include criteria on their checklists. Figure 4 shows pass/ fail criteria established for measuring brake stroke taken from CHAPTER FOUR SURVEY RESULTS: CONDUCTING PREVENTIVE MAINTENANCE-RELATED ACTIVITIES

26 • Engine oil pressure, fan speed, and idle speed • Alternator amperage and voltage outputs • Transmission and retarder performance • Bus ride height. Specific inspection criteria provide technicians with refer- ence for what is acceptable and ensures that inspections are done in a consistent manner and in compliance with regula- tory requirements. Agencies typically establish pass/fail and other criteria through a combination of OEM specifications and U.S.DOT requirements. Criteria listed on agency check- lists must be consistent with these requirements; those who violate them are subject to the penalty provisions of CFR 49 Part 396.17, Periodic Inspections (17). Depending on the infraction, the DOT can issue a warning, levy a fine, or even close the maintenance operation. Inspection criteria that breach OEM requirements can result in rejection of warranty claims. Written Job Instructions PM tasks are more effectively carried out when technicians are provided with precise instructions that reflect the agency’s work expectations. A majority agree, as 79% of those respond- ing to the survey develop written instructions for PM-related activities. One resource for developing written procedures is TCRP Report 109: A Guidebook for Developing and Shar- ing Transit Bus Maintenance Practices (18). The Guidebook includes several examples of PMI instructions and checklists complete with inspection criteria. One approach to developing written PMI instructions is where materials used by the agency’s training department are consistent with, if not identical to, reference materials avail- PM Activity Those Using Generic Checklist Those Using Unique Checklist Bus PMI 39% 61% HVAC PMI 38% 62% Lift/ramp PMI 37% 63% TABLE 13 POPULAR PMIs WHERE CHECKLISTS ARE USED Inspect and measure brake pushrod stroke. Brake Stroke Measurements Axle Stroke Front axle 1.75” max Drive axle 2.0” max Record Brake Stroke Measurements: LF ______ RF ______ LR ______ RR ______ Slack adjuster to push rod angle approximately 90o with brakes applied Ensure full range of brake movement without binding Pass Fail FIGURE 4 Brake stroke measurement criteria. Capital Metro’s PMI checklist for Optima buses. The check- list includes space for technicians to list measurements for each wheel location, and provides additional information for carrying out the procedure. The chapter five case study for the Whatcom Transportation Authority in Bellingham, Washington, highlights the agency’s emphasis on requir- ing technicians to conduct tests and take measurements as part of PMIs. Other areas where PMI criteria are provided include: • Battery voltage • Tire tread depth • DPF backpressure • Brake interlock regulator setting • Suspension kingpin play • Door open/close speed • Air compressor cut-in pressure • Brake S-cam bushing wear, lining thickness, and drum temperature variances • Wheel lug nut torque • Exhaust smoke opacity • Air system pressure build-up time

27 able to technicians in the workshop. An exceptional example of PMI instructions is produced by the Central Florida Regional Transportation Authority (LYNX) in Orlando. The opening paragraph to their Preventive Maintenance Procedure Manual, which contains detailed step-by-step instructions for each PMI task, makes several significant points: The preventive maintenance procedures and checklists contained in this document were assembled and defined with the assistance of Lynx’s Technicians, Training Assistants, Supervisors and other staff employees. The process of updating this document and our Preventive Maintenance Program is ongoing. Procurement of new equipment and/or technology, failure of systems and/or com- ponents as well as other factors can effect changes in our Preven- tive Maintenance Program. The statement clearly indicates the importance of developing instructions as a joint labor–management effort, where both sides accept the procedures as appropriate. LYNX also recog- nizes the importance of continually updating the inspection process based on changing technology and new information. Instructions are divided into various sections, each with color photos, clear instructions on when to bring abnormalities to the attention of a supervisor, specific pass/fail criteria, and references for each major PMI activity where technicians can find more detailed information when needed. A portion of those instructions is included as Appendix G. Everett Transit in Washington uses an approach where its MIS, based on bus number, prints out the appropriate PM checklist complete with work instructions and pass/fail crite- ria. By having checklists in an electronic format the agency can update them as needed, providing technicians with a cur- rent checklist each time a PM activity is conducted for a par- ticular bus. The Whatcom Transportation Authority in Bellingham, Washington, also provides technicians with PM checklists and detailed instructions for each vehicle type. Doing so helps the agency adhere to DOT requirements, as summa- rized in the Literature Review section of chapter two and detailed in Appendix C. LABOR AND SPARE RATIO CONSIDERATIONS Skilled Versus Entry-Level Survey responses indicated a split regarding skill levels required to conduct PM inspections, with 60% using skilled technicians, 16% using entry-level, and 24% using other skill levels, primarily a combination of both. Reasons given for each approach are compelling. Those who favor skilled workers stated that technology is dynamic and changing as buses evolve, and increased skill sets are needed even for basic PM tasks. They also contend that skilled technicians better satisfy contractual obligations with OEMs and legal DOT requirements, and are more qualified to assess equip- ment condition and identify defects. Conversely, some who favor using entry-level technicians maintain they have no “bad habits” and can be trained from the start on how to do a PMI correctly. Others use lower skill level workers when possible as a training process to help them learn vehicles. Some agencies only hire skilled techni- cians, making the issue mute. Some who use a combination of worker skills limit unskilled workers to basic tasks such as service line inspec- tions and the cleaning of filters and radiators. Others use entry-level workers to perform inspections and then follow up with a skilled technician for verification and repair. Some pair up skilled and entry level technicians for training pur- poses. One agency trains all workers to conduct PMIs to achieve “a singularity of effort,” to get away from the mind- set where technicians are responsible for particular jobs. Splitting Work Responsibilities Survey responders are also divided on whether to use the same technician to conduct all aspects of PM or split respon- sibilities between routine tasks and more demanding ones; 61% have the same technician conduct all PM activities; 39% split responsibilities. Those who maintain one skill level in their workshop have no choice. Some who split responsibili- ties use a technician with limited abilities for routine PM tasks while using specialists to work on brakes, air conditioning, engine tune-ups, tires, and other more critical areas. Some use specialized electronic shop personnel to perform all farebox, radio, and AVL-related PM. Because of DOT inspection requirements for brakes and air conditioning, some agencies specifically use specialists dedicated in these PM areas. Some agencies assign one technician to PM activities for better work accountability. When several technicians are involved it can become unclear as to who completed the task. Having a single technician responsible for the entire PMI also avoids one technician interfering with another’s work, and avoids confusion as to who completed—or did not complete— specific aspects of the PM. Others use a single technician until the shift ends when another takes over. Some agencies assign one technician to shorter-duration PMIs and double up when PMs are more comprehensive. Other agencies favor a team approach, where each technician is assigned certain bus areas. Agencies such as the Chicago Transit Authority assign inspection-only activities to one group of technicians and the repair of identified defects to another. The advantage is that dedicated and specially trained technicians only focus on identifying defects with no responsibility for repairing them. The disadvantage is that buses need to be rescheduled for lubrication servicing and repair of noted defects. Work Rules and Standards When asked if work rules influence the type of skilled tech- nician allowed to conduct PM activities, 39% of survey

responders reported having such rules, whereas the majority (61%) do not. Other work rules are union-related where cer- tain job classifications require certain skills. At some level agencies require basic rules because of DOT training and experience requirements, especially those pertaining to brakes and air conditioning refrigerant. The Whatcom Transportation Authority (WTA) uses only journey level technicians with in-house certification to inspect and repair vehicles. Doing so helps ensure that regulatory requirements are met. The certification program came about because the manager realized that checklists were lacking; each technician determined if a component or system was in safe operating condition. That determination, according to the manager, “was all over the map.” The in-house-developed cer- tification program, described further as a case study in chapter five, establishes inspection and repair standards and removes any ambiguity when performing inspections. Time Calculations Seventy-four percent of responding agencies calculate time needed to conduct PM activities, 26% do not. One responder gave up calculating time because technicians are called away so often that timeframes are not very accurate, and instead goes by “ball park numbers” that the agency believes “are close.” Giving up, however, is not appropriate. Auto dealer- ships and private trucking companies routinely account for the time needed to conduct maintenance activities. The United Parcel Service, for example, calculates the time of every fleet activity down to the minute, and evaluates main- tenance costs as a percentage of the cost to ship an average package (19). Calculating PM time is essential for establishing budgets and staffing levels. PM that becomes more effective at reduc- ing breakdowns, however, will not necessarily reduce overall labor requirements because of increased preventive measures added to scheduled activities. Time spent on PMs as reported by survey responders also varied with “A” PM inspections ranging from 1 to 5 h. The median of 3 h, however, represents a more realistic time for this inspection. Table 14 shows the average and median number of hours reported by 28 agencies to conduct “A,” “B,” and “C” PM inspections. As indicated in 28 this table, the mean hours to complete a “B” inspection adds 2 h of additional activities to the “A” inspection for a total of 5 h, whereas the “C” inspection averaged another 5 h of activ- ities for a total of 8 mean hours. Bus Spare Ratio Half of agencies responding to the survey calculate the num- ber of spare vehicles needed to support their PM program. Of those, 55% report needing 20% spare vehicles, consistent with the FTA maximum allowance. It is assumed that many in this category have simply cited the FTA requirement with- out making formal calculations. The 20% ratio required for PM does not provide for additional spare buses needed for unscheduled maintenance, accident damage, and other non- PM related maintenance activities. The remaining responses most likely reflect the actual number of spare buses needed to support PM activities. Excluding those reporting the FTA maximum of 20%, 44% require a spare ratio of 5% to 6%, 33% require 10% to 12% spares, and 22% need 15% spares. PREVENTIVE MAINTENANCE COSTS When asked if PM costs are calculated in terms of combined parts and labor, 63% do, whereas 37% do not. Although most understand the importance of identifying PM costs, the high number (more than 1 in 3) that does not track this important indicator is alarming. Table 15 shows combined parts and labor costs calculated by agencies to conduct most common PMIs. Again, the large disparity in cost reflects the wide vari- ety of fleet equipment, PM activities, and nomenclature used by agencies to define various PM events. Pre-Packaged Preventive Maintenance Parts Kits One way to improve the efficiency of PM inspections is to pre-package kits with all needed parts and supplies. Filters, gaskets, hardware, and replacement parts required for routine servicing can be pre-packaged into convenient kits and handed to technicians with the work order when PMIs are assigned. Doing so not only ensures technicians will install needed parts, but avoids the unproductive time associated with technicians waiting at the parts counter while parts are collected. PM Bus PMI A Bus PMI B Bus PMI C HVAC PMI Lift/Ramp PMI Low ($) 31 54 91 225 108 High ($) 364 790 965 1,078 860 Average ($) 184 291 459 623 369 Median ($) 162 208 448 566 140 PM Bus PMI A Bus PMI B Bus PMI C HVAC PMI Lift/Ramp PMI Low (hours) 1 1.5 2 1 0.75 High (hours) 5 10 14 8 8 Average (hours) 3.1 4.8 7.3 3.6 2.5 Median (hours) 3.0 5.0 8.0 3.0 2.0 TABLE 14 LABOR HOURS NEEDED TO CONDUCT PMIs TABLE 15 PARTS AND LABOR COSTS NEEDED TO CONDUCT PMIs

29 Of survey responders, 51% reported that their work order generates a parts kit containing all parts needed for each par- ticular PM activity; 49% do not. Agencies that pre-package parts kits noted that they have one prepared for each PM type. Some agencies stated that they would implement such a procedure after reading the survey question. Other agencies identify parts needed for each PM but do not consolidate them into kits. QUALITY ASSURANCE PROCEDURES In a perfect world workers would do their jobs properly and oversight would not be needed. Given the safety implica- tions of conducting PMIs, however, QA becomes an essen- tial element of the PM function. A majority of survey respon- ders (79%) have QA measures in place for PM activities. Of those that do, 41% conduct random or spot inspections. Cap- ital Metro in Austin, Texas, inspects 5% to 10% of all PMIs, whereas San Diego Metropolitan Transit System conducts QA spot inspections quarterly. The QA program used by Beaver County Transit in Pennsylvania is driven by drivers’ daily reports and road calls. Montgomery County, Maryland, rarely conducts QA spot checks on individual buses, but uses another procedure to oversee its PM program. Dispatch logs are reviewed weekly to identify service interruptions caused by mechanical fail- ures. Previous work orders are reviewed to note if other fac- tors could have led to the failure, and to determine if a PM task could be put in place to prevent reoccurrences. REPAIR OF NOTED DEFECTS Each PM inspection typically results in a list of identified defects. Exactly when those defects are repaired is deter- mined by agency policy. Regardless of policy, agencies typically address critical and safety-related defects imme- diately and then deal with less critical defects as time and resources allow. Milwaukee County Transit “red tags” critical defects that must be repaired before buses can be released for service. The maintenance software program at WTA will not allow safety-related defects to be deferred— they must be repaired. Agencies that allow buses back into service with safety- related defects do so at great risk. Defects not considered safety-critical or time-sensitive could certainly be resched- uled for a later time. However, as mentioned earlier, contin- ually postponing the repair of defects over time will cause buses to become unappealing to riders and get to the point where a deteriorated fleet condition becomes accepted. Of responding agencies, 46% reported that all defects are immediately repaired unless parts are not available, 8% repair all defects that can be done within a set time period (e.g., 1 h, up to 2 h, or 3 h), and 11% schedule identified defects for repair at a later time. Remaining agencies cite other repair policies. Of agencies that schedule repairs for a later date, 62% track follow-up completion by keeping work orders open, 12% use software programs or spreadsheets, and 12% use a manual system. One agency reported not tracking completion of noted defects at all.