Document ID: FRA-2009-0031-0096
Agency: fra
Document Type: Notice
Title: Safety Advisory 2013-02; Low-Speed, Wheel-Climb Derailments of Passenger Equipment with Stiff Suspension Systems
Posted Date: 2013-03-14T04:00Z

[Federal Register Volume 78, Number 50 (Thursday, March 14, 2013)]
[Notices]
[Pages 16358-16361]
From the Federal Register Online via the Government Printing 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