JUNE 2017 | MassTransitmag.com | Mass Transit | 27
2. Perform Inspections
and Tests
Begin the inspections with an
evaluation of the vehicles’ most
critical areas: structure and
electrical systems. Th ese critical
systems are the most likely to infl
uence life extension decisions
because of their cost and impact
on vehicle operation.
Carbody and truck structures
are typically susceptible to fatigue
cracking and corrosion damage.
Expert fractography can be used
to investigate the cause of cracks
that are found during inspection.
Additionally, dynamic in-service
testing, in which strain, acceleration
and displacement of key
structural and suspension elements
are measured, will indicate
the forces and stresses experienced
by the vehicle while in service.
Due to budgetary and other
practical limitations, the number
and location of strain gages applied
must be carefully considered.
It is important to enlist the
help of experienced analysts to
properly predict fatigue-prone
areas. Th e results of the dynamic
testing will be compared with
mechanical properties of components
and weld classifi cations to
predict remaining service life of
the carbody and truck structures.
In parallel with the structural
evaluation, review the major electrical
power, passenger comfort,
system safety and control systems.
Vehicle control and communications
systems demand special
attention, as they are safety-critical
and are heavily dependent
on oft en obsolete electronics and
soft ware. Systems integration is
another area of focus, especially
when considering the retrofi t
of legacy systems with modern
technologies. Examples include
installation of new systems, such
as communications-based train
control (CBTC) and closed circuit
TV (CCTV), as well as retrofi tting
controls for propulsion, brake and
door systems.
3. Summarize Findings
Th e results of the information
gathering and inspection eff orts
are summarized into a report.
Th e report must present the results
of the assessment in a clear and
concise manner that will easily
be understood by both technical
and non-technical members of the
management team.
4. Conduct Financial
Analyses
Once completed, the fl eet assessment
will serve as a valuable
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