[Federal Register Volume 78, Number 50 (Thursday, March 14, 2013)]
[Notices]
[Pages 16358-16361]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-06000]
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DEPARTMENT OF TRANSPORTATION
Federal Railroad Administration
Safety Advisory 2013-02; Low-Speed, Wheel-Climb Derailments of
Passenger Equipment With ``Stiff'' Suspension Systems
AGENCY: Federal Railroad Administration (FRA), Department of
Transportation (DOT).
ACTION: Notice of Safety Advisory.
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SUMMARY: FRA is issuing Safety Advisory 2013-02 to alert railroads and
other industry members about low-speed, wheel-climb derailments of
certain passenger equipment designs having ``stiff'' suspension
systems. These derailments have occurred when such equipment was
negotiating track with a high degree of curvature and crosslevel
variations (commonly referred to as ``track warp'') that were still
within the limits set forth in FRA's Track Safety Standards. The
findings from the derailment investigations conducted by FRA and the
respective railroads highlight the need to ensure that passenger
equipment suspension systems are suitable for more-demanding track
conditions found in low-speed operating environments. To avoid similar
low-speed, wheel-climb derailments, this notice recommends that
railroads and other industry members evaluate the trackworthiness of
certain passenger equipment to determine whether the suspension systems
meet truck-equalization industry standards, prevent wheel climb, and
control static wheel-load distribution under the conditions and within
the limits described in the notice; and take appropriate action to
address the derailment tendency, if any, of the evaluated equipment. In
order to minimize the risk of suspension spring failure, this notice
also recommends that railroads and other industry members assessing the
fatigue life of suspension springs and their corresponding maintenance
intervals use a fatigue-evaluation load equal to the equipment's full-
capacity loading conditions.
FOR FURTHER INFORMATION CONTACT: Michelle Muhlanger, Deputy Regional
Administrator, Region 1, Office of Railroad Safety, FRA, 55 Broadway
Street, Cambridge, MA 02142, telephone (617) 494-2630; Gary Fairbanks,
Staff Director, Motive Power and Equipment Division, Office of Railroad
Safety, FRA, 1200 New Jersey Avenue SE., Washington, DC 20590,
telephone (202) 493-6322; or Anna Nassif Winkle, Trial Attorney, Office
of Chief Counsel, FRA, 1200 New Jersey Avenue SE., Washington, DC
20590, telephone (202) 493-6166.
SUPPLEMENTARY INFORMATION:
Background
In response to increased performance objectives, such as higher
operating speeds and increased passenger capacity, passenger equipment
suspension systems are becoming stiffer \1\ and more sophisticated, and
may be approaching design limits. In many cases, engineering tradeoffs
are made to meet performance objectives and satisfy specific system
constraints (e.g., clearances for existing tunnels or other
infrastructure). An example is equipment using non-linear vertical
springs, which provide variable stiffness as the vehicle load increases
from AW0 (i.e., empty vehicle ready to run) to AW3 (i.e., vehicle with
full-seated and full-standee load). Such tradeoffs have resulted in
certain newer designs of equipment being operated over more-demanding
track geometry conditions with lower margins of safety, from a
derailment perspective, than older equipment designs. The static weight
distribution and marginal wheel-load equalization that are
characteristic of such suspension system designs can lead to wheel
unloading. This is of particular concern because FRA has determined
that the combination of high, lateral curving forces and wheel
unloading is a major contributing factor to low-speed,\2\ wheel-climb
derailment tendency. Similar wheel-climb derailments are not as likely
to occur at higher speeds on higher classes of track because track
curvature is generally less sharp and the safety limits on track-warp
variations on such track are more stringent. See Title 49 Code of
Federal Regulations (CFR) 213.63 and 213.331.
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\1\ Suspension systems that allow lower suspension deflection
for the same load (e.g., due to the use of less flexible springs).
\2\ Fifteen mph or less. The maximum allowable operating speed
for passenger trains on Class 1 track, as defined under 49 CFR
213.9, is 15 mph. All references in this notice to a section or
other provision of a regulation are to a section, part, or other
provision in 49 CFR.
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Although the derailments prompting issuance of this safety advisory
all occurred on Class 1 track at speeds of 15 mph or less, and did not
result in any injuries, the consequences could have been much worse.
For example, one of the derailments resulted in the derailed train
fouling the adjacent track on which a National Railroad Passenger
Corporation (Amtrak) Acela Express train was traveling. Had the
circumstances been different, a significant collision could have
occurred. Thus, the recommendations in this notice are important not
only in preventing low-speed, wheel-climb derailments themselves but in
preventing what may be more serious consequences of such derailments.
Although Federal regulations require suspension systems on Tier II
\3\ passenger equipment to reasonably prevent wheel climb and wheel
unloading under all loading conditions and at all track speeds (see
Sec. 238.427), there is no equivalent requirement for Tier I passenger
equipment (see
[[Page 16359]]
Sec. 238.227). Further, while the March 13, 2013, final rule on
vehicle/track interaction (VTI) safety standards will promote the safe
interaction of all rail vehicles with the track over which they operate
under a variety of conditions, the rule focuses on high-speed and high
cant deficiency operations, and does not address--in particular--the
prevention of the type of low-speed, wheel-climb derailment that is the
focus of this notice.
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\3\ Tier II passenger equipment operates at speeds exceeding 125
mph but not exceeding 150 mph, whereas Tier I passenger equipment
operates at speeds not exceeding 125 mph. See Sec. 238.5.
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During the development of the VTI rule and as a result of working
with a number of railroads to investigate several low-speed, wheel-
climb derailments at that time, FRA recognized the need to address such
derailments more comprehensively. Specifically, FRA was concerned that
there needed to be greater compatibility between certain designs of
passenger equipment (i.e., those having ``stiff'' suspension systems)
and the lower track classes over which they operated, as such equipment
was experiencing derailments while negotiating track with a high degree
of curvature and with track warps that were still within the limits set
forth in FRA's Track Safety Standards. The Railroad Safety Advisory
Committee (RSAC) task force that was assigned to assist FRA in
developing the VTI rule was initially tasked to consider addressing the
issue in that rulemaking. However, the task force, with the concurrence
of the full RSAC, recommended that the issue be addressed by an
industry standard on truck equalization, rather than in the VTI rule.
To that end, the American Public Transportation Association (APTA)
issued a standard on truck equalization.\4\ However, the APTA standard
applies to passenger equipment suspension systems loaded in the AW0
condition only, as wheel load equalization was traditionally seen as an
issue principally affecting empty cars. Although APTA members recently
voted to re-open the standard to incorporate further lessons learned
from recent derailment investigations, FRA recognizes that it will take
some time to do so. This notice of safety advisory is intended to more
fully address the issue in the meantime.
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\4\ See APTA SS-M-014-06, Standard for Wheel Load Equalization
of Passenger Railroad Rolling Stock (2007).
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Discussion of Specific Recommendations
The first recommendation is that railroads and other industry
members conduct a trackworthiness evaluation of certain passenger
equipment to determine whether suspension systems meet truck-
equalization industry standards, prevent wheel climb, and control
static wheel-load distribution under certain conditions and within
certain limits. Because the manufacturing process inherently results in
small variances in some of the vehicle's components, vehicle designs
necessarily include a nominal value for certain components, as well as
tolerances for those components. The designs also specify tolerances
for maintenance limits to account for in-service wear and degradation
of components. Thus, a trackworthiness evaluation of a vehicle type's
performance should also take into account the full range of component
tolerances (e.g., spring heights) and maintenance limits (e.g., wheel
wear). Railroads and industry members should be aware that vehicles may
or may not exhibit derailment tendencies over the range of new vehicle
component tolerances. Similarly, vehicles with in-service wear that are
still operating within all maintenance tolerances may or may not
exhibit derailment tendencies. Therefore, it is important to consider
all combinations of component and maintenance tolerances in evaluating
trackworthiness.
Although conducting such an evaluation at the design stage for new
equipment is both desirable and feasible from a practical standpoint,
FRA recognizes that it would be quite burdensome to conduct such an
evaluation for all existing equipment. Therefore, FRA has focused the
recommendations regarding existing equipment in this notice to
situations that are easier to address or where the equipment is at
greatest risk for experiencing similar derailments. Consequently, FRA
is limiting the formal recommendations in this notice to existing
equipment that (1) Is undergoing a redesign of its suspension system
that will likely affect the low-speed trackworthiness performance of
the vehicle; (2) is being placed in service over a new route that the
railroad knows to have more demanding track geometry conditions; or (3)
has experienced one or more low-speed, wheel-climb derailments that may
have involved a combination of wheel unloading and track warp of 3
inches or less as a contributing factor.
In addition, if the results of a trackworthiness evaluation
indicate that the equipment's performance does not meet one or more of
the conditions described, FRA is recommending different levels of
action depending on whether the equipment is new (or redesigned) or
existing. For new equipment or equipment undergoing a redesign of its
suspension system that will likely affect the low-speed trackworthiness
performance of the vehicle, FRA recommends that the suspension system
be redesigned to perform according to the conditions described. For
existing equipment, FRA is recommending that appropriate action be
taken to mitigate the derailment tendency. This would include
redesigning the equipment or taking other appropriate action, such as
ensuring that the track over which the equipment is operating is
maintained to standards appropriate for the specific equipment type, or
placing operational restrictions on the equipment, or both. FRA
believes that this approach makes the recommendations more effective
and focused.
FRA notes in particular that the reason for including in these
recommendations existing equipment that is being placed in service over
a new route that the railroad knows to have more demanding track
geometry conditions is because the equipment may be subjected to
different track conditions (e.g., a route with higher-degree-of-
curvature track or a route with track that is maintained to lower
standards) and interact differently with the track, potentially leading
to similar wheel-climb derailments. In addition, FRA believes that some
railroads may not be aware that the equipment they are operating is
prone to such derailments because they are already taking some action
that mitigates the derailment tendency of the equipment. For example, a
railroad may have decided, for unrelated reasons, to maintain the track
over which the equipment travels to higher, Class 2 standards, even
though the track is formally designated as Class 1. If the railroad
were to stop maintaining this track to Class 2 standards without taking
any other action to mitigate the risk (e.g., by putting operational
restrictions on the equipment), it is possible that the equipment would
begin exhibiting similar derailment tendency.
Recognizing that certain newer suspension system designs may result
in equalization performance in the AW3 loading condition that makes the
equipment more prone to derailment than when it is in the AW0 loading
condition, FRA believes it is important to evaluate the equalization of
suspension systems in the AW3 loading condition as well. Accordingly,
FRA recommends that railroads and other industry members ensure that
such evaluation is conducted using the AW3 loading condition for all
new passenger equipment and for the three categories of existing
equipment identified in this
[[Page 16360]]
notice. This will help ensure that the suspension system will be able
to prevent wheel unloading when the equipment is loaded to capacity.
Although assessment of wheel-load equalization is important in
preventing the wheel unloading and wheel climb indicated in the subject
derailments, FRA has determined that the tests and analyses typically
used for evaluating wheel-climb and wheel-unloading tendency could be
enhanced by including a curving-performance assessment with track-warp
variations at the Class 1 limits \5\ for a broad spectrum of
wavelengths. For example, in reviewing the information available for
eight recent low-speed, wheel-climb derailments \6\ involving multi-
level vehicles,\7\ it was discovered that three of the vehicles
derailed at or near track warps of a broad spectrum of wavelengths
(i.e., a 3-inch track warp in 62 feet, a 1.75-inch track warp in 30
feet, and a 2-inch track warp in 10 feet). Although track geometry data
was not recorded for all eight incidents, based on the computer
modeling conducted by the equipment manufacturer during the derailment
investigations to assess the capabilities of the subject vehicle type,
it is likely that the five other vehicles derailed under similar
circumstances. Thus, FRA is recommending that all new, and the three
categories of existing, passenger equipment identified in this notice
be evaluated to determine whether the suspension systems prevent wheel
climb while negotiating, at a minimum, a 12-degree curve with a
coefficient of friction (COF) representative of dry track conditions
(i.e., 0.5) and 3-inch track warp variations with the following
wavelengths: 10, 20, 40, and 62 feet. FRA also recommends that, under
both the AW0 and AW3 loading conditions, the ratio of lateral force to
vertical force (``L/V ratio'') on any wheel not exceed, for a duration
of more than 5 feet, the ratio given by Nadal's limit with a COF of 0.5
(i.e., the FRA single-wheel L/V ratio criterion in Sec. 213.333).
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\5\ See Sec. 213.63, prescribing limits for the difference in
crosslevel between any two points (measured along the rails of the
track) less than 62 feet apart. For FRA Class 1 track, the
difference in crosslevel may not be more than 3 inches.
\6\ Nothing in this safety advisory is intended to place
responsibility for these incidents on the acts or omissions of any
person or entity.
\7\ These multi-level vehicles were placed in service between
2006 and 2008, and were designed to provide stable operation at
speeds up to 125 mph and meet clearance requirements.
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In addition, FRA notes that sensitivity studies conducted by the
equipment manufacturer and FRA using computer modeling indicate that an
uneven wheel-load distribution has a significant influence on the
margin of safety against derailment. That is, passenger equipment with
a wheel having a static load up to 10-percent below the nominal load
can tolerate significantly less track warp even when the equipment
meets the APTA equalization standard. Therefore, FRA is recommending
that all new passenger equipment and the three categories of existing
passenger equipment identified in this notice be evaluated to determine
whether the suspension systems control static wheel-load distribution
when the equipment is stationary on perfectly level track such that the
lightest wheel load deviates by no more than 5 percent from the nominal
wheel load.
Furthermore, while the subject derailments were primarily related
to trackworthiness issues, in several other recent low-speed
derailments, FRA has determined that broken primary springs were a
contributing factor. Although it appears that high coil-to-coil contact
stresses within the end coils were a large contributing factor to the
broken suspension springs in these derailments, FRA is also aware that
spring failures are likely to occur when the fatigue life of suspension
springs and their corresponding maintenance intervals are inadequately
determined.
Additionally, FRA understands that softer springs, which may be
selected to provide better wheel-load equalization (and correspondingly
decrease the likelihood of the subject low-speed derailments), may be
more prone to failure and consequently may need more frequent
maintenance than the stiffer springs. In order to ensure that springs
are capable of withstanding both the static and dynamic loads imposed
in service under all passenger loading conditions from empty (AW0) to
full capacity (AW3), FRA is recommending that the fatigue life of
suspension springs and their corresponding maintenance intervals be
determined using a fatigue-evaluation load equal to the full-capacity
loading conditions. As is the case with the other recommendations in
this notice, FRA has limited the applicability of this recommendation,
namely by applying it to all new passenger equipment designed with
suspension springs, and existing passenger equipment with such springs
when the springs are redesigned.
FRA believes that addressing the above interrelated issues through
the recommended measures will reduce the risk of wheel-climb
derailments over more-demanding track geometry conditions found in low-
speed operating environments. In addition, FRA anticipates that
implementation of the recommendations through redesign will promote
interoperability of passenger equipment throughout the U.S rail network
and help avoid the need for equipment-specific track geometry limits or
operational restrictions, or both.
Recommended Action: In light of the observed passenger equipment
design trends and recent incidents, FRA recommends that railroads and
other industry members take the following actions:
1. Evaluate the trackworthiness of the following equipment types
intended for use in the United States:
All new passenger equipment types.
Any existing passenger equipment type that is undergoing a
redesign of its suspension system that will likely affect the low-speed
trackworthiness performance of the vehicle.
Any existing passenger equipment type that is being placed
in service over a new route that the railroad knows to have more-
demanding track geometry conditions (e.g., curvature, warp, etc.).
Any existing passenger equipment type that has experienced
one or more low-speed, wheel-climb derailments that may have had a
combination of wheel unloading and track warp of 3 inches or less as a
contributing factor.
Such evaluation should take into account the full range of
component tolerances and maintenance limits, and determine whether--
a. Suspension systems meet the APTA truck equalization standard,
APTA SS-M-014-06, Standard for Wheel Load Equalization of Passenger
Railroad Rolling Stock (2007), under both the AW0 and AW3 loading
conditions.
b. Suspension systems prevent wheel climb while negotiating, at a
minimum, a 12-degree curve with a COF representative of dry track
conditions (i.e., 0.5) and 3-inch track warp variations with the
following wavelengths: 10, 20, 40, and 62 feet. Under both the AW0 and
AW3 loading conditions, the L/V ratio on any wheel should not exceed,
for a duration of more than 5 feet, the ratio given by Nadal's limit
with a COF of 0.5 (i.e., the FRA single-wheel L/V ratio criterion in
Sec. 213.333).
c. Suspension systems control static wheel-load distribution when
the equipment is stationary on perfectly level track such that the
lightest wheel load deviates by no more than 5 percent from the nominal
wheel load.
2. If the results of the trackworthiness evaluation conducted in
accordance with recommendation 1 of this notice indicate that the
passenger equipment does not meet one or more of the conditions
specified in that
[[Page 16361]]
recommendation, or if a railroad otherwise has knowledge that the
equipment does not meet one or more of these conditions, take
appropriate action to address the equipment's derailment tendency as
follows:
a. For new equipment or equipment undergoing a redesign of its
suspension system that will likely affect the low-speed trackworthiness
performance of the vehicle, as applicable, redesign the suspension
system so that it meets truck-equalization industry standards, prevents
wheel climb, and controls static wheel-load distribution under the
conditions and within the limits specified in recommendation 1 of this
notice.
b. For existing equipment that is being placed in service over a
new route that the railroad knows to have more-demanding track geometry
conditions, or that has experienced one or more low-speed, wheel-climb
derailments, as described in this notice, redesign the suspension
system as described in recommendation 2a of this notice, or take other
appropriate action to mitigate the derailment tendency, such as by
ensuring that the track over which the equipment is operating is
maintained to standards appropriate for the specific equipment type, or
by placing operational restrictions on the equipment, or both.
3. For all new passenger equipment types designed with suspension
springs, and for existing passenger equipment types with such springs
when the springs are redesigned, ensure that the fatigue life of the
springs and their corresponding maintenance intervals are determined
using the AW3 loading condition.
FRA encourages railroads and other industry members to take actions
that are consistent with the preceding recommendations and to take
other actions to help ensure the safety of the Nation's railroads,
their employees, and the general public. FRA may modify this Safety
Advisory 2013-02, issue additional safety advisories, or take other
appropriate actions it deems necessary to ensure the highest level of
safety on the Nation's railroads, including pursuing other corrective
measures under its rail safety authority.
Issued in Washington, DC, on March 11, 2013.
Robert C. Lauby,
Deputy Associate Administrator for Regulatory and Legislative
Operations.
[FR Doc. 2013-06000 Filed 3-13-13; 8:45 am]
BILLING CODE 4910-06-P