System-Specific Spare Bus Ratios Update (2014) / Chapter Skim
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7 the respondents by geographic region and fleet size (with agency bus fleet size noted in parentheses)
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Bus Fleets 25–99 -- Small 100–249 -- Medium 250–499 -- Large 500–999 -- Very Large >1,000 -- Mega U.S. North-Central Connect Transit, Bloomington, IL(29)
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9 and contracted fleet operations, their fleets were combined. Table 3 summarizes the distribution of respondents by their 2012 annual vehicle-miles operated and fleet size grouping.
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10 five of the nine fleets had a spare ratio larger than 20%. One of the nine contacted fleets did not supply sufficient data to calculate the spare bus ratio.
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11 Looking at agency spare ratio trends over past five years, 16 of the 35 (46%) directly operated agency fleets were able to reduce their spare ratios from 2008 to 2012; 13 (37%)
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12 responses to questions on fleet-related attributes and service and operating environmental attributes. Survey respondents were asked to provide information concerning fleet-related attributes, including average age, the number of advanced on-board technologies in the fleet, and alternative fueling/energy technologies; and their impacts on their agency's spare vehicle needs and spare ratio levels.
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FIGURE 4 Correlation of average bus age (years) with spare ratio over time -- both directly operated and contracted fleets.
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14 fleet.
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16 (23 agencies, or 60%) ; shuttle services (15 agencies, or 39%)
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17 • "Plug buses" for overloads and/or schedule compliance/ "catch-up" • Training • Other emergency or special need • None of the above or not applicable. Table 12 summarizes the types of special or intermittent services needs as represented among the surveyed agency fleets.
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18 Duty Cycles The survey asked respondents to indicate the relative proportion of its bus operations that fall within three intensity levels of duty cycles: • Heavy (intensive stop/start/dwell) • Medium (moderate stop/start/dwell)
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19 Level of Maintenance Staffing Respondents -- including technicians who actually work on the vehicles and their systems and sub-systems, but not fuelers, cleaners, tire-servicers, etc. -- were asked to compute the ratio of technicians to buses. Responses were provided in different formats, making comparisons difficult.
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20 Out-of-Service Criteria The survey queried respondents concerning the criteria under which a bus is pulled from service, as one of the factors that may influence spare bus requirements. Respondents were asked to indicate which of the following out-of-service criteria they apply through policy or procedure: • Any defect that precludes the safe operation of the bus • Any defect that limits the accessibility of the bus (malfunctioning lift, ramp, kneeling mechanism, etc.)
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21 Twenty-one of the 38 (55%) survey respondents pointed to constraints associated with a limited number of maintenance bays and a need to shuttle vehicles between facilities.
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22 • 3 -- Moderate influence • 4 -- Significant influence. The result was a weighted ordering of each factor in terms of its relative influence on the number of spare buses that the collective survey respondents are required to maintain (see Table 18)
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23 years. Nineteen of the 38 (50%)
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24 • The movement of retired buses into a contingency fleet • The sale of buses to reduce the overall number of vehicles in the fleet to meet reduced transit service levels • The replacement of coaches in smaller groups, allowing for reduced decommissioning batches • Focused effort on and closer supervision of the management of small sub-fleet spares and division-to-division resource sharing • Implementation of annual bus purchases through a 10-year contract with a single supplier that incorporates minimal specification changes from year to year, which also reduces training requirements and spare parts issues • Decline or deferral of some special requests to a better time (when more spare buses are available) ; allocation of different spare ratios to different fleet types at each depot; revision of spare factors for each depot quarterly so that each depot is assigned the appropriate number of buses • Working to establish CNG as a reliable alternative fuel choice • Dedication to long-term asset management strategy.
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25 • Improved training for maintenance staff and the resources to do so • Stabilizing reliability of alternative fueling and advanced technologies (e.g., gasoline-hybrids) • Increased commonality in buses and bus technologies • Implementing proactive maintenance programs to reduce life-cycle costs, improve reliability, and minimize down time because of mechanical failures • Pursue greater uniformity in bus fleet; maximize interchangeability of buses in the fleet to allow flexibility in order to meet service demands; avoid specialty vehicles for specific routes to facilitate meeting pull-out with limited spare buses.
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