Beginning the Dialogue - Report on SGR - Federal Transit ...

Preventive Maintenance
most common and, perhaps, best understood type of
transit asset and hence best positioned for PM
standardization). Over <strong>the</strong> period 1999 to 2002, <strong>the</strong>
Federal Transit Administration (FTA) collected data
on <strong>the</strong> vehicle inspection and PM programs of a
sample of forty-three U.S. transit bus operators as
part of a bus condition assessment program. This
analysis documented a wide range of vehicle PM
inspection frequencies for standard forty-foot transit
buses – ranging from every 2,000 to 8,000 miles
(with every 6,000 miles being <strong>the</strong> most common). As
expected, <strong>the</strong> thoroughness of <strong>the</strong> inspections and
related preventive maintenance activities also varied
widely (with <strong>the</strong> thoroughness of <strong>the</strong>se activities not
well correlated to <strong>the</strong> frequency of <strong>the</strong> inspections).
Interestingly, <strong>the</strong>re was no observed relationship
between <strong>the</strong> physical condition of <strong>the</strong> vehicles and
<strong>the</strong> frequency of vehicle inspections. A similar study
of rail transit vehicles yielded similar results.
Based on this research, it is clear that PM
frequencies and activities are far from standardized
across <strong>the</strong> nation’s transit operators (at least for
vehicle fleets). The question remains <strong>the</strong>n as to
whe<strong>the</strong>r PM practices should be standardized. Here
again, FTA’s condition research for bus and rail
assets provides a helpful perspective. These
condition assessments documented how differences
in <strong>the</strong> service and environmental characteristics of
individual transit operators impacted <strong>the</strong>ir assets’
physical conditions, life expectancy and maintenance
needs. Specifically, <strong>the</strong>se maintenance needs and
asset conditions were related to each of <strong>the</strong> following
factors:
n Ridership levels
n Annual hours and miles of service (e.g., per
vehicle)
n Climate/environment (e.g., presence of salt)
n Make and Model
The analysis suggested that operators with higher
ridership, higher asset utilization (e.g., annual miles
per vehicle) or more severe climates should expect
that more frequent or more comprehensive
34
preventive maintenance activities may be required to
ensure <strong>the</strong>ir assets are maintained in good working
order. Similarly, <strong>the</strong>re are also variations in <strong>the</strong>
reliability of differing pieces of transit equipment of
<strong>the</strong> same type – yielding yet ano<strong>the</strong>r variable to
identification of an optimal PM program. Toge<strong>the</strong>r,
<strong>the</strong>se considerations suggest that it may not be
possible or sensible to apply standardized, “one size
fits all” PM programs to assets of <strong>the</strong> same type but
of differing quality and applied in widely different
operating environments.
r PREVENTIVE MAINTENANCE AND
STATE OF GOOD REPAIR
What, <strong>the</strong>n, are <strong>the</strong> relationships between preventive
maintenance and state of good repair (SGR)? A
primary consideration here is whe<strong>the</strong>r <strong>the</strong> concept of
preventive maintenance should be included within <strong>the</strong>
definition of “state of good repair.” Specifically, can
an asset or transit system be in a state of good repair
if its preventive maintenance requirements are not
met? The position taken here is that a
comprehensive PM program is a necessary condition
to ensure that SGR is maintained but that occasional
or temporary postponement of some PM activities
does not imply that a system (or asset) is not in a
state of good repair.
A second consideration here is <strong>the</strong> impact of
differences in <strong>the</strong> comprehensiveness of preventive
maintenance programs on asset conditions, asset life
expectancy and, by extension, state of good repair.
In o<strong>the</strong>r words, do more comprehensive programs
effectively yield better asset conditions and longer
asset life? Here again, FTA’s asset condition
research provides a valuable perspective.
Specifically, this research considered how differences
in preventive maintenance practices impacted asset
physical condition (see chart below for 40-foot transit
buses). This analysis demonstrated fairly effectively
that transit assets (again primarily vehicles) subject to
higher levels of preventive maintenance tend to be of
higher physical condition at all asset ages (implying
longer asset life) as compared to similar assets
subject to less comprehensive PM programs. These