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A-1
APPENDIX A:
Effect of Wheel/Rail Profiles and Wheel/Rail
Interaction on System Performance and
Maintenance in Transit Operations
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EFFECT OF WHEEL/RAIL PROFILES AND WHEEL/RAIL
INTERACTION ON SYSTEM PERFORMANCE AND
MAINTENANCE IN TRANSIT OPERATIONS
SUMMARY The research team performed a survey of representative transit systems to identify
the common problems and concerns related to wheel/rail profiles in transit operations.
This survey was conducted as part of Phase I of this project to develop wheel/rail pro-
file optimization technology and flange climb criteria.
The research team conducted onsite surveys at six representative transit systems that
involve both light rail and rapid transit operations to collect information related to
wheel/rail profiles and wheel/rail interactions. Several vehicle maintenance shops and
track sites were visited to observe current wheel/rail profile related practices and prob-
lems. Summaries of the information from five of the systems visited are included in the
Appendixes A-1 through A-5.
The survey identified the following common problems and concerns related to
wheel/rail profiles and wheel/rail interaction in transit operation:
· Adoption of low wheel flange angles can increase the risk of flange climb derail-
ment. High flange angles above 72 degrees are strongly recommended to improve
operation safety.
· Rough wheel surface finishes from wheel re-profiling can increase the risk of
flange climb derailment. Final wheel surface finish improvement and lubrication
could mitigate the problem considerably.
· Introduction of new wheel and rail profiles need to be carefully programmed for
both wheel re-profiling and rail grinding to achieve a smooth transition.
· Without adequate control mechanisms, independently rotating wheels can produce
higher lateral forces and higher wheel/rail wear on curves.
· Cylindrical wheels may reduce the risk of vehicle hunting, but can produce poor steer-
ing performance on curves.
· Some wheel and rail profile combinations used in transit operations have not been
systematically evaluated to ensure they have good performance on both tangent
track and curves under given vehicle and track conditions.
· Severe two-point contact has been observed on the designed wheel/rail profile
combinations from several transit operations. This type of contact tends to produce
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A-4
poor steering on curves, resulting in higher lateral force and a higher rate of
wheel/rail wear.
· Track gage and restraining rails need to be carefully set on curves to allow suffi-
cient RRD and to reduce some high rail wear and lateral force.
· Wheel slide and wheel flats occur on several transit systems, especially during the
fall season. Although several technologies have been applied to mitigate the prob-
lem, transit operators are in need of more effective methods.
· Generally, noise related to wheels and rails is caused by wheel screech/squeal,
wheel impact, and rail corrugations. Wheel/rail lubrication and optimizing
wheel/rail contact could help to mitigate the noise problems.
· Wheel/rail friction management is a field that needs to be further explored. Appli-
cation of wheel/rail lubrication is very limited in transit operation due to the com-
plications related to wheel slide and wheel flats.
· Reduction of wheel/rail wear can be achieved by optimization of wheel/rail pro-
files, properly designed truck primary suspension, improvement of track mainte-
nance, and application of lubrication.
· Without a wheel/rail profile measurement and documentation program, transit
operators will have difficulty reaching a high level of effectiveness and efficiency
in wheel/rail operation and maintenance.
· Further improvement of transit system personnel understanding of wheel/rail pro-
files and interaction should be one of the strategic steps in system improvement.
With better understanding of the basic concepts, vehicle/track operation and main-
tenance activities would be performed more effectively.
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A-5
CHAPTER 1
INTRODUCTION
This project included two phases (Table A-1). these standards are unique to a particular system. Older sys-
This report describes the methodology and engineering tems frequently have wheel and rail profile standards that were
behind wheel/rail profile optimization and the results derived established many years ago. For some older systems, the rea-
from the work performed in Task 1, Phase I of the program. sons that specific profiles were adopted have been lost in time.
Newer systems have generally selected the wheel/rail profiles
based on the increased understanding of wheel/rail interaction.
1.1 BACKGROUND Increasing operating speed and introducing new designs of
vehicles have further challenged transit systems to maintain
A railroad train running along a track is one of the most
and improve wheel/rail interaction. Good overall perfor-
complex dynamic systems in engineering due to the many
mance can be achieved by optimizing vehicle design, includ-
nonlinear components. The interaction between wheels and
ing suspension and articulation, to work with optimized
rails is an especially complicated nonlinear element of the
wheel and rail profiles. However, possibilities of modifying
railway system. Wheel and rail geometry--involving cross
existing vehicles are limited. Along with other activities,
section profiles, geometry along the direction of travel, and
optimization of wheel/rail contact is one of the strategies for
varying shapes due to wear--has a significant effect on vehi-
maintaining or improving vehicle performance.
cle dynamic performance and operating safety.
Transit systems are usually operated in dense, urban areas,
which frequently results in lines that contain a large percent- 1.2 OBJECTIVES
age of curves, or curves with small radii, which can increase
wheel and rail wear and increase the potential for flange climb There are two main objectives of wheel/rail profile assess-
derailments. Transit systems also operate a wide range of vehi- ment technology development:
cle types, such as those used in commuter rail service, heavy
or rapid transit and light rail vehicles, with a wide range of sus- · Identify common problems and concerns related to
pension designs and vehicle performance characteristics. wheel/rail profile and interaction in transit operations.
In general, transit systems (in particular, light rail and sub- · Provide guidelines to transit system operators for wheel/
way systems) are locally operated. Without the requirement of rail profile assessment, monitoring, and maintenance.
interoperability, many transit systems have adopted different
wheel and rail profile standards for different reasons. Some of This appendix fulfills the requirement of the first objective.
TABLE A-1 Tasks in the program of wheel/rail profile optimization technology and
flange climb criteria
Program Tasks
Define common problems and concerns related to wheel/rail
Task 1
profiles in transit operation
Phase I
Propose preliminary flange climb criteria for application to transit
Task 2
operation
Develop general guidelinesfor wheel/rail profile assessment
Task 1
applied to transit operation
Phase II
Propose final flange climb derailment criteria validated by the
Task 2
test data
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A-6
CHAPTER 2
METHODOLOGY
To develop wheel/rail profile assessment technology, the Transportation Association (1) and the research team's knowl-
existing problems and concerns related to wheel and rail pro- edge of these systems, as shown in Table A-2. These systems
files in transit operations first need to be identified. A survey operate a large number of cars and have a variety of types of
has been conducted of selected transit systems to examine the operation. They are mainly located in four geographic areas:
current state of common practices in wheel/rail operation and
maintenance. · Washington, D.C.--Baltimore
· Chicago
· California
2.1 SELECTION OF SYSTEMS FOR
SITE VISITS · the Northeast (BostonNew YorkPhiladelphia)
The research team compiled a partial list of transit systems The research team visited several of these transit agencies
based on the 2003 Membership Directory of American Public to perform the survey. Due to budget limitations, the team sur-
TABLE A-2 List of large transit systems
Light Rail Bi- Rapid Commuter
Transit System Cars level Transit Coach Locomotive Total Geographic area
1 San Francisco Bay Area Rapid Transit (BART) 669 669
2 San Francisco Municipal Railway 136 136 California
3 Southern California Regional Rail Authority (Los Angeles) 146 37 183
4 Metropolitan Atlanta Rapid Transit Authority 238 238 Atlanta
5 Chicago Transit Authority 1190 1190 Chicago
6 Chicago Metra 781 165 139 1085
7 Massachusetts Bay Transportation Authority 185 408 362 80 1035
8 New Jersey Transit Corporation (NJ TRANSIT) 45 844 139 1028 Northeast
9 Port Authority Transit Corporation (Lindenwold, NJ) 121 121
10 Metropolitan Transportation Authority (New York) 8231 8231
11 Port Authority Trans-Hudson Corporation (New York) 342 342
12 Southeastern Pennsylvania Transportation Authority 197 345 349 891
13 Maryland Transit Administration 53 100 110 30 293 Washington
14 Washington Metropolitan Area Transit Authority 882 882 D.C. /Baltimore
TABLE A-3 Transit systems visited during the survey
Area Agencies Visited
· MBTA
Trip 1 Northeast
· New Jersey Transit Corporation (NJ TRANSIT)
· Washington Metropolitan Area Transit Authority
Washington, D.C. and
Trip 2 (WMATA)
Philadelphia
· SEPTA
· Chicago Transit Authority (CTA)
Trip 3 Chicago area · Chicago Metra (not included in the summaries
of site visits)
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A-7
veyed six systems in three main geographic areas (Table A-3). 2.3 ANALYSIS OF SURVEY INFORMATION
These six systems are considered representative of transit
operations in North America. The research team has carefully studied the information
from the survey. Analysis has been performed with an
emphasis on the wheel/rail profiles and issues related to
2.2 SITE VISIT wheel/rail interaction. These issues include the following:
During each site visit, the following information was · Typical wheel/rail profiles used in transit operations.
researched: · Wheel/rail contact patterns.
· Wheel/rail wear patterns.
· Current problems related to the wheel/rail profiles in · Safety concerns related to wheel/rail profiles.
that system. · Vehicle curving performance and lateral stability
· Historical information of wheel/rail related problems. behavior as affected by wheel/rail profiles.
· Map of route, curve distribution, and operating speed. · Other issues related to wheel/rail profiles.
· New wheel/rail profile designs.
· Worn wheel/rail profiles, if available.
2.4 IDENTIFYING COMMON WHEEL/RAIL
· Wheel/rail wear historical data. PROFILE ISSUES
· Vehicle design information.
· Rail lubrication practices. Based on the survey and the survey information analysis,
· Current wheel/rail maintenance practice. the common problems and concerns related to wheel/rail pro-
· Any other wheel/rail related problems. files in transit systems were identified and are further sum-
marized in this appendix. Based on the survey, there is a clear
Results from the individual surveys are contained in the understanding of what guidelines transit operators need
Appendixes A-1 to A-5. related to wheel/rail profiles.
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A-8
CHAPTER 3
TRANSIT SYSTEM SURVEY
As a way of focusing expectations, prior to each visit to the of wheel/rail issues. Five major topics were included in the
representative transit systems, a questionnaire was sent to a presentation:
primary contact person at each location focusing on the fol-
lowing topics: · Fundamentals of wheel and rail contact.
· Vehicle dynamics related to wheel and rail shapes.
· Problems caused by incompatible wheel/rail profiles.
· Existence and type of wheel/rail profile related prob-
· Wheel/rail lubrication.
lems on the system.
· Wheel/rail maintenance.
· Remedies tried (successfully or not) for the wheel/rail
problems.
After the initial seminar, a group discussion was held to
· Determining whether the problems are specific to par-
explore wheel/rail topics. With the involvement of personnel
ticular vehicle types and/or track locations.
from operations, track maintenance, and vehicle maintenance,
· Opinions of existing track and/or car conditions versus
many problems and concerns were reviewed at a systems
design and maintenance standards.
level. The discussion continued with individual interviews,
· Lubrication practices.
during which the research team collected much information
· Employee wheel/rail interface training needs.
related to practice, standards, and rules. At each site visited, a
· Existence of a wheel re-profiling program.
wheel/axle/car shop tour was conducted with a primary
· Existence of, and criteria for, a rail grinding program.
mechanical representative. Then, an on-track visit and dis-
· Percentage of budget spent on various facets of wheel/rail
cussion was performed with an engineering representative.
maintenance.
Appendixes A-1 to A-5 provide a brief summary of the
· Any other vehicle performance research.
information from each individual system visited. These sum-
· Driving factors behind the wheel/rail work (e.g., eco-
maries have been reviewed by the relevant systems to ensure
nomics, safety).
the accuracy of the information. The topics in each summary
· Major corrections needed to improve wheel and rail
include the following:
interaction.
· Wheel and rail profiles.
Each visit began with a presentation on the effect of · Wheel life and wheel re-profiling.
wheel/rail interaction on vehicle performance to groups · Rail life and rail grinding.
that included track maintenance, vehicle maintenance, and · Track standards.
operating personnel. This presentation (approximately · Fixation methods.
1 hour long) was intended to improve the group's under- · Lubrication and wheel slide.
standing of wheel/rail contact systems and the importance of · Noise.
wheel/rail profile optimization and to stimulate discussion · Major concerns and actions.
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A-9
CHAPTER 4
COMMON PROBLEMS OR CONCERNS RELATED
TO WHEEL/RAIL PROFILES
The common problems and concerns discussed in this sec- 4.1 WHEEL FLANGE ANGLE
tion are summarized from the survey information. They may
not apply to every transit system. An issue is addressed here The maximum flange angle of the designed wheel profiles
because it was of interest or was considered by more than one applied in transit operation ranges between 63 and 75
system and because it falls into the general area of wheel/rail degrees. Table A-4 lists the wheel flange angles received for
interaction. the six visited systems.
In this section, the following issues related to wheel/rail It was noticed that the wheel profile drawings received
profiles and wheel/rail interactions are discussed: from some systems have no direct measure of wheel flange
angle. Some flange angles listed in Table A-4 were obtained
· Wheel flange angle. by converting the wheel profile drawings received to CAD
· Surface finish from wheel re-profiling. drawings. Then the flange angles were accurately derived
· System transition in increasing wheel flange angle. from the CAD drawings. During the survey, when asked
· Independently rotating wheels. about the flange angle, the engineers in the vehicle mainte-
· Cylindrical tread wheels. nance group usually would only reference the drawings but
· Wheel/rail contact condition analysis. not know the actual angle if there was no direct measure of
· Track gage and flangeway clearance. flange angle in the drawing.
· Wheel slide and wheel flats. The maximum wheel flange angle () is defined as the
· Noise. angle of the plane of contact on the flange relative to the hor-
· Rail lubrication. izontal (Figure A-1), and it has a significant effect on wheel
· Wheel/rail wear. flange climb derailment. Figure A-1 illustrates the system of
· Wheel/rail profile monitoring and documentation. forces acting on the flange contact point. Lateral force (L)
and vertical force (V) are exerted on the rail by the wheel.
A brief description of the theories related to each issue is Reacting forces exerted on the wheel by the rail are the nor-
provided for a better understanding on the cause of the prob- mal force (F3) and the lateral creep force (F2) in the plane of
lem and the damage that might result. contact.
TABLE A-4 Maximum wheel flange angle of designed wheels (the blank indicates no
such service in that system)
Rapid Transit
Light Rail Cars Commuter Cars
System Cars
Flange Angle Flange Angle
Flange Angle
63 degrees (in the No information was No information was
MBTA
transition to 72 degrees) received received
NJ TRAN SIT 75 degrees 72 degrees
60-65 degrees
SEPTA 63 degrees 72 degrees
(in specified tolerance)
WMATA 63 degrees
Chicago Metra 75 degrees
CTA 68 degrees
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A-10
angle, and the other wheel profile has a 63-degree flange
angle. At a friction coefficient of 0.5, which is the dry
wheel/rail contact condition, the limiting L/V value is 1.13
for wheel profiles with a 75-degree flange angle (such as the
AAR-1B wheel) and 0.73 for the wheels with a 63-degree
flange angle. Clearly, wheels with low flange angles have a
higher risk of flange climb derailment.
Increasing the design wheel flange angle to reduce the risk
of flange climb derailment has been a common practice for
Figure A-1. Flange forces at wheel climb. transit systems. Due to historic reasons, some older transit sys-
tems have adopted relatively low wheel flange angles in the
range of 63 to 65 degrees. The low flange angles are prone to
Equating forces in the lateral and vertical directions give flange climb derailment and have less compatibility with dif-
the following equation: (2) ferent truck designs. Newer transit systems generally start with
a wheel profile having a flange angle of 72 to75 degrees.
L tan - F2 F3 A wheel profile with a higher flange angle can reduce the
= (A-1) risk of flange climb derailment and can have much better
V 1 + F2 tan F3
compatibility with any new designs of vehicle/truck that may
be introduced in the future compared to wheels with lower
This equation gives the minimum L/V ratio at which flange angles. Also, with higher L/V ratio limits (according
flange climb derailment can occur for any value of F2/F3 at a to the Nadal flange climb criterion), high flange angles will
specified maximum contact angle. Nadal's criterion (3), pro- tolerate greater levels of unexpected track irregularity.
posed in 1908 and still used extensively for derailment
assessment, can be derived from Equation A-1 for the satu-
F2 4.1.1 Derailments of Low Floor Light Rail
rated condition of = µ where µ = the coefficient of
F3 Vehicles Due to Low Flange Angle
friction between the wheel and the rail (see Equation A-2):
Figure A-3 compares two examples of designed wheel
profiles used by transit systems. First is a wheel profile with
L tan - µ a flange angle of 63 degrees that was previously applied to
= (A-2)
V 1 + µ tan all vehicles on MBTA's Green Line (light rail), including
new Number 8 cars. The second example is the profile
If the maximum contact angle is used, Equation A-2 gives applied to the NJ TRANSIT's Newark city subway (light
the minimum wheel L/V ratio at which flange climb derail- rail) with a flange angle of 75 degrees.
ment may occur for the given contact angle and friction coef- As shown in Figures A-4 and A-5, MBTA's Number 8
ficient µ. In other words, below this L/V value, flange climb cars have a structure similar to that of the NJ TRANSIT light
cannot occur. Figure A-2 plots the relation of limiting L/V rail cars (LRVs) with the low-platform level boarding and
ratio and maximizing flange angle at different levels of fric- low floor for handicapped accessibility. These types of cars
tion coefficient between wheel and rail. have three sections and double articulation at the center unit.
Figure A-2 gives two examples of wheel flange angles. The center unit is equipped with independent rotating
One is the AAR-1B wheel profile with a 75-degree flange wheels.
2
0.1 0.2 0.3 0.4
1.8
1.6
Nadal L/V Value
1.4 0.5
1.2
1
0.8
0.6 1.0
0.4
0.2
0
45 55 65 75 85
Flange Angle (Degree)
Figure A-2. Relationship of limiting wheel L/V ratio and
maximum flange angle. Figure A-3. Examples of designed wheel profiles.
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A-11
angle. In 1993, six low speed flange climb derailments
occurred on curves in the yards. Guardrails were installed
later in those derailment locations. In August 2003, a flange
climb derailment occurred on a service train. Among other
causes, the consultant for the derailment investigation has
suggested that the 63-degree flange angle may have
increased the risk of flange climb derailment. WMATA has
been considering the improvement of wheel profile to a
larger flange angle of 72 to 75 degrees.
Figure A-4. The Number 8 car of MBTA Green Line. 4.1.3 Additional Transit System Wheel Profile
Designs
The cars from these two light rail systems show different Among the 14 wheel profile drawings of U.S./North
dynamic performance due to the differences in suspension and American light rail systems that are included in the Track
wheel profile design. However, the 63-degree wheel flange Design Handbook for Light Rail Transit (excluding SEPTA
angle, combined with other track and vehicle situations, appar- and MBTA wheel profiles, which have been discussed in
ently contributed to derailments of the Number 8 cars in 2000 Table A-4), 8 have no direct measures of flange angle, and 2
and 2001. One of MBTA's remedial actions has been to of the remaining 6 have a design flange angle of 63 degrees
increase the wheel flange angle from 63 degrees to 75 degrees (4).
by introducing a new wheel profile. Rail grinding has also been This handbook proposed a wheel flange angle of 70
performed to reshape the rail gage corner to help the wheels degrees based on Heumann's design. The APTA's Passen-
maintain the 75-degree flange angle. Combined with other ger Rail Safety Standard Task Force Technical Bulletin (5)
improvements in track maintenance, the derailment of the provides guidance on reducing the probability of wheel-
Number 8 cars due to the low flange angle has been eliminated. climb derailment, suggesting a minimum wheel flange angle
In comparison, there are no derailment concerns with the of 72 degrees (suggested tolerances are +3.0 degrees and
similar cars on the NJ TRANSIT subway system. The wheels -2.0 degrees).
in the cars were designed with a 75-degree flange angle.
4.2 WHEEL RE-PROFILING
4.1.2 Derailment of Rapid Transit Vehicles Due
4.2.1 Rough Surface from Wheel Re-Profiling
to Low Flange Angle
To reduce wheel and rail wear, WMATA adopted the Wheel truing is a process that re-profiles the wheel shape
British worn tapered wheel profile in 1978 to replace the old and removes surface defects such as flats, spalls, and
cylindrical profile. This wheel profile has a 63-degree flange shellings. Two types of wheel re-profiling machines are com-
monly used. Figure A-6 shows the milling type, which has a
cutting head with many small cutters. The arrangement of the
cutters forms the wheel profile. Figure A-7 shows the lathe
type, which has a wheel profile template; the single cutter
cuts the wheel by following the shape of a template.
Figure A-5. NJ TRANSIT LRV. Figure A-6. Milling type wheel re-profiling machine.
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A-12
Generally, the coefficient of friction for dry and smooth
steel-to-steel contact is about 0.5. The effective coefficient of
friction for rough surface condition can be much higher. For
example, if the friction coefficient reaches 1.0, the L/V limit
would be 0.5 for a 75-degree flange angle and 0.3 for a
63-degree flange angle (as shown in Figure A-2). Therefore,
the rough surface produced by wheel re-profiling could sig-
nificantly reduce the L/V limit for flange climb. The low
flange angle further increases the derailment risk.
Several remedies may improve the surface condition:
· Frequently inspecting the cutting tools--especially for
Figure A-7. Lathe type wheel re-profiling machine. the milling type machine. Dulled tools can produce a
very rough surface. Sometimes the grooves on the
wheels were obvious.
Several systems have reported flange climb derailments · Addressing the final surface tuning. In this step, there is
occurring at curves or switches in yards when the cars were no significant material removal but rather a light cut for
just out of the wheel re-profiling machines. This type of smoothing the surface. WMATA has included this step
derailment was likely caused by the wheel surface roughness in its wheel re-profiling procedures.
after wheel re-profiling. Figure A-8 compares the wheel sur-
faces just after re-profiling and the surface after many miles Further, lubrication after re-profiling can be an effective way
of running. The left wheel in Figure A-8 was re-profiled by to prevent flange climb derailment on newly re-profiled wheels.
the milling type machine with very clear cutting traces on the Again, referring to Figure A-2, reducing the friction coefficient
surface. The middle wheel was re-profiled by a lathe type at wheel/rail interface can increase the L/V limit for flange
machine with shallower cutting traces. The right wheel was climb. The sharp asperities on the wheel surface after re-
returned to the shop from service with a smooth surface but profiling may quickly deform or wear off in operation due
had a flat spot on the tread. to very high locally concentrated contact stress. After some
(a) (b) (c)
Figure A-8. Comparison of wheel surface roughness. (a) Surface after wheel re-profiling from milling
type machine, (b) Surface after wheel re-profiling from lathe type machine, and (c) surface of wheel back
from operation with a flat spot.
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A-34
Rail wear was mentioned as an issue for a few curves. In A2.5 FIXATION METHODS
these cases, rail life may be as short as 6 years. Two exam-
ple scenarios were discussed: The Newark City Subway currently uses wood ties on bal-
last, except in stations where dual block wood is set in con-
crete. A planned service extension will be near both an his-
· At a grade crossing near Gladstone, the curve is elevated
toric church and a performing arts center. Therefore, a
to 1.5 in. underbalance (designed for 45 mph traffic),
floating slab design has been specified to reduce noise and
but traffic actually operates around 25 mph due to the
vibration. The cost of this is estimated to be three to five
crossing. This results in faster low rail wear and some
times that of conventional track.
track movement.
The commuter operations at NJ TRANSIT use conven-
· Some sharper curves, which would normally receive
tional wood tie/cut spike construction with premium fasten-
flange lubrication, have no lubricators installed due to
ers on some curves. That is, curves greater than 2 degrees
other concerns such as losing traction or braking capa-
(2,900-foot radius) are gradually being re-fit with Pandrol
bility on a grade.
fasteners and lag screws. Previously, NJ TRANSIT used
hairpin-type fasteners in the curves, but the fasteners did not
NJ TRANSIT commuter operations report no programmed hold.
rail profile grinding operations. Limited spot grinding is used
to return the rail shape to a new profile, but it is not generally
targeted toward specific rolling contact fatigue issues. Newly A2.6 LUBRICATION AND WHEEL SLIDE
installed rail is commonly ground after 1 year to remove sur-
face defects or corrugations. A2.6.1 Light Rail
Approximately twice a year, an ultrasonic and induction
The Newark City Subway applies a variety of rail lubrica-
rail inspection is conducted across the system, uncovering 8
tion methods in its system. Wayside flange lubricators and
to 15 defects each time. Neither rail shelling nor corrugations
wayside top-of-rail friction modifier systems are operating,
are significant issues.
and an onboard lubrication system is currently under test.
In the yard there are eight lubricators using regular grease
for the flange side and the back of the wheel.
A2.4 TRACK STANDARDS Wayside top-of-rail friction modifiers have been installed
at the 60-foot and 82-foot curve radius turnaround loops at
Track Geometry Standards (known as MW4) are mainly
Penn Station (tunnel) and at the 100-foot radius (outdoor)
used by the commuter rail system and are used as a guide for
curve at Franklin Street. Site inspections confirmed that no
the Newark City Subway. City Subway staff report that City
wheel screech was perceived at these locations. NJ TRAN-
Subway follows much tighter classifications for its operation
SIT reports no adverse effects of weather on the vehicle per-
than FRA would prescribe. For example, the light rail track
formance using the friction modifier outdoors.
gage dimension is a nominal 56 1/2 in., with a +1/4 in. and
A concern for the Subway during autumn and spring is the
-0 in. tolerance, and the maximum operating speed is
so-called "black rail," a slippery condition caused by falling
50 mph. The FRA standard for commuter rail gage is a nom-
leaves combining with morning dew and dust. When wet, the
inal of 56 1/2 in. with a +1 in. and -1/2 in. tolerance for
leaves are smashed by passing wheels and become a low-
speeds above 60 mph.
friction contaminant. This black rail condition can cause
The Newark City Subway experienced a derailment dur-
adhesion and braking problems systemwide. Efforts were
ing turnout negotiation on a Number 10 Samson switch. It
made to improve the resulting low friction conditions via
has been determined that the AREMA 5200 detail at the
track cleaning with an electric rotating brush, but NJ TRAN-
Samson type switch and the quality of point adjustment to the
SIT did not report success. Rather, the brushing operation
stock rail was not adequate and may always create a hazard.
tended to merely distribute the contaminant evenly across the
Consequently, housetop point protection was retrofitted to all
rail. Since then, NJ TRANSIT has procured a hi-rail water jet
switches.
cleaner operating at 20,000 psi with much improved results.
FRA track geometry standards apply on the NJ TRAN-
SIT commuter lines. The National Railroad Passenger Cor-
poration (Amtrak) track geometry car is currently used A2.6.2 Commuter Rail
across the system quarterly. The Amtrak inspections of the
550-mi track typically yield about five to eight track geom- About 80 wayside lubricators are installed on the com-
etry defects. NJ TRANSIT intends to perform 8 to 10 muter rail system curves. There is an ongoing debate within
inspections per year. Programmed surfacing is performed NJ TRANSIT about the minimum curvature that should
on a 5- to 10-year interval and tends to follow the tie receive a wayside lubricator. A systemwide review of rail
replacement cycle. profiles and lubricator placement is underway.
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A-35
As mentioned previously, some curves that would nor- and wheel wear are being closely monitored, as evident by
mally receive flange lubrication have no lubricators installed the use of MiniProf data from every wheel.
because of other concerns, such as losing traction or braking Various existing mitigation techniques oriented toward
capability on a grade. wear, noise, and safety have been implemented:
Leaf residue on the tracks is also a seasonal problem for
the commuter operations. · Wayside flange lubrication.
· Wayside top-of-rail friction modification.
A2.7 NOISE · Special trackwork point guards.
· Optimization of restraining rails on curves.
Noise and vibration is an important issue for the Newark City
Subway, especially for the rail sections that are close to resi- Additionally, prototype onboard flange lubrication is
dential areas. NJ TRANSIT has oriented some of their rail lubri- being tested and a program of preventative rail profile grind-
cation efforts to reduce noise levels as well as wear. At a turn- ing is planned.
around curve (82-foot radius) in the Vehicle Base Facility yard
and a few other locations, the wayside flange lubricators are
used to reduce wheel squeal and wear. A similar success has A2.8.2 Commuter Rail
been implemented at a sharp, in-street curve at Franklin Avenue
via a wayside top-of-rail friction modifier. Also recently, squeal NJ TRANSIT's commuter rail wheel/rail profile mainte-
noise has been reduced underground at the sharp Penn Station nance is an ongoing process. Daily flange width and wheel
curve via a top-of-rail friction modifier. As mentioned, the flat inspections, as well as suitable capacity in the two wheel
Newark City Subway is also making efforts to improve vehicle re-profiling shops result in good maintenance of wheel tread
curving by properly adjusting rail gage and flange way clear- profiles.
ances, which should also reduce the noise on curves somewhat. Past problems and solutions for the NJ TRANSIT com-
Unlike the City Subway, noise has not been an important muter system have included the following:
issue on the NJ TRANSIT commuter operations. This is
expected, given that commuter systems often operate with · Vehicle hunting--reduced by implementing 1:40 tread
greater separation from residential and business areas. tapers.
· Low-speed flange climb at special trackwork--
A2.8 MAJOR CONCERNS AND ACTIONS improved by implementing higher flange angle wheels.
· Slow-speed derailments in yards (especially with newly
A2.8.1 Light Rail cut wheels)--reduced by giving greater attention to
yard track quality.
As a newly updated system overall, the Newark City Sub- · Low-speed flange climb when local operations are con-
way is maintaining a high level of operational quality with siderably below the designed balance speed--reduced
extensive efforts toward preventative maintenance. Both rail by reengineering elevations at some curves.
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APPENDIX A-3
SEPTA
SEPTA has a very diverse infrastructure with operations
including commuter, rapid transit, and light rail.
Both the City Transit (Green Line) and Suburban Light
Rail Lines (Routes 101 and 102) use similar 50-foot long
Kawasaki LRVs. However, the wheel profiles and track gage
are different between the city and suburban lines.
SEPTA's three rapid transit lines are the Market-Frankford
(Blue) Line, the Broad Street Subway (Orange), and the
Norristown Route 100 (Purple) Line. The Blue line oper-
ates 55-foot long Bombardier M-4 stainless steel cars. The
Orange Line has a fleet of Kawasaki B-IV cars each 67.5 ft
in length. The Purple Line (Route 100) has a fleet of N-5 cars
from Bombardier.
Regarding commuter operations, the majority of SEPTA
vehicles are 85-foot long Silverliner type vehicles from Figure A3-1. SEPTA cylindrical wheel wears into slightly
Budd, St. Louis Car, and GE. Other types of commuter cars hollow but stable shape on Suburban Route 101, LRV.
include 85-foot electric push-pull cab cars and coaches from
Bombardier.
The regional (commuter) line cars use 32-in. diameter
wheels with 75-degree peak flange angle and 1:20 taper. The
current rail standards for the commuter rail system are the
A3.1 WHEEL AND RAIL PROFILES 115RE and the 132RE.
The diameter of all LRV wheels is 27 in. The wheel pro-
file for the LRV cars on the Green Line has a 63-degree A3.2 WHEEL LIFE AND WHEEL RE-PROFILING
flange, a 1:20 tread taper, and a flat top flange that may help
to reduce the contact stress as wheels pass special flange- The light rail lines (including the Norristown route)
bearing trackwork. achieve about 150,000 to 200,000 mi between re-profiling.
A cylindrical tread wheel profile is applied on the LRV The average wheel life is about 10 years.
cars operating on Routes 101 and 102. This wheel profile was The City Transit LRV (Green Line) wheels are generally
inherited from previous cars. Analyses of tolerances for the re-profiled due to flange issues. Field inspections showed that
flange root width show this to have a peak flange angle that these wheels often encounter street debris in the girder rail
is between 60 and 65 degrees. When new, these cylindrical flangeway. As such, they experience excessive riding on the
wheels tend to wear quickly to a slightly hollow tread, as top of flange. The 101/102 LRV wheels are re-profiled at
shown in Figure A3-1. They then stabilize to a reasonably about a 5-year interval, based on a predicted usage of 33,000
constant shape. Field observations of tangent tracks on the mi per year.
Route 101 indicated a narrow contact band, skewed some- SEPTA has two re-profiling machines, a lathe type
what towards the gage face of the rail. re-profiling machine and a milling-head re-profiling
The light rail lines use 100RB rail. The rail gages are wider machine. The lathe machine has a single-point cutting tool
(ranged from 62.25 to 62.5 in.) than standard gage of 56.5 in. that produces a smoother surface finish compared to that
On the Orange (Broad Street Subway) Line cars, 28-in. from the milling machine.
wheels are used with a 63-degree flange angle and a 1:20 The milling machine has a cutting head with many small
tread taper. Except for the commuter rail lines, the new rail cutters (staggered to form the wheel profile). SEPTA
laid are 115RE . However, former rail standards have left expressed particular interest in any potential flange climb
80- to 100-lb/yd rail in some sections. effects caused by smoothness differences between left and
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right wheels on the same axle. Such differences have been For standard gage lines, contractors are used for infrequent
seen when using one sharper cutting head and one dull head. grinding. SEPTA now replaces rails in tunnels when profile
The SEPTA wheel diameter tolerances after re-profiling or surface problems are advanced. During recent experience
1/8 in. within the same axle, 1/4 in. axle-to-axle in the same with rail grinding in a tunnel, it was found that the spread of
truck, and 1/2 in. truck-to-truck difference in the same car. grinding dust, air contamination, and expensive station
As with all the systems visited, SEPTA has experienced cleanup made rail grinding in those areas unfeasible with the
low-speed derailments, and almost all of them were flange available equipment.
climbs in yard tracks. Some of these were associated with SEPTA reported that asymmetric grinding on some curve
newly re-profiled wheels. Wheel surface roughness after sections successfully improved vehicle curving and resulted
wheel re-profiling, combined with SEPTA's low flange in reduced wear and noise.
angles, could considerably reduce the L/V limit ratio Like other transit systems, SEPTA has had track corruga-
required for wheel climb. tion problems at specific locations. Rail grinding is required
On the commuter lines, operating miles are not tracked periodically in these zones to remove severe corrugations.
and therefore wheel lives are not known. Generally these
wheels are trued for flat spots caused by braking and/or rail
contaminants. A3.4 TRACK STANDARDS
Commuter rail lines follow FRA track safety standards.
A3.3 RAIL LIFE AND RAIL GRINDING The light and heavy rail track is maintained to SEPTA inter-
nal track standards. In brief, SEPTA track geometry stan-
Rail lives vary from 6 years (tighter curves) to 40 years (tan- dards are similar to the FRA standards, although oriented
gent track). Curves over 5 degrees (1150-foot radius) tend to toward 31-foot mid-chord lengths. (Gage specifications are
wear quickly and are typically replaced within 5 to 7 years. equal to the FRA rules. Alignment specifications are under
On the rapid transit lines, fast wear in some tangent areas 1/2 in. of the FRA allowances. Vertical profile and cross
can be attributed to significant use of track brakes under the level rules are similar to the FRA rules, and the track twist
cars. Alternating gage face wear between left and right rail rules are slightly under the FRA allowances.)
was reported at a certain locations. The causes are still under Light rail lines are designed to 4.5 in. maximum under-
investigation. balance. All other lines allow up to 3 in. underbalance. Head-
As shown in Figure A3-2, the rail at certain sections of the hardened rails are installed on curves. Guardrails are
Green Line had significant wear or surface damage. The installed for rapid transit curves wherever tighter than 750 ft
damage is likely caused by wheel impacts upon street debris in radius.
in the girder rail flangeway. This can locally lift the tread To improve vehicle curving and to reduce gage face wear
contact and cause wheel impacts at an adjacent section. of the high rail on tight curves, track gage is intentionally
For the wide gage light rail lines, SEPTA owns an 8-stone widened up to 1 in. in places. However, SEPTA has concerns
grinding machine. Rail profile grinding is targeted toward about how much worn rail conditions effect the optimum
producing an 8-in. rail head crown radius. effective gage on different curvatures.
Figure A3-2. Rail surface damage on Green Line.
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Regarding commuter operations, a track geometry car tives, and by manually placing small solid disks of com-
inspects track every third month. Walking track inspections pressed sand on the rail head.
are performed once a week for sections having less than 5 A new, speed-sensing , dynamic braking control system is
million gross ton (MGT) traffic per year and twice a week for being implemented in the rapid transit operation to reduce
sections having traffic more than 5 MGT per year. wheel sliding during braking.
Various maintenance intervals are used on the light rail
and rapid transit lines (including limited cross tie and rail
replacement, and surfacing where necessary). As a long-term A3.7 NOISE
goal, SEPTA is planning to achieve the track standards one
The rapid transit lines (Market-Frankford and Broad
class higher than the FRA specification.
Street) and the City Transit light rail lines converge under the
Philadelphia City Hall. This array of tunnels and stairwells is
A3.5 FIXATION METHODS excessively noisy due to the combinations of squeal, flang-
ing noise, wheel impacts, and rolling noise.
Rail fixation for the various SEPTA rapid transit lines The Broad Street cars are subjectively deemed to be quite
ranges from direct fixation (e.g., wood half-ties set in con- noisy, although it is believed that they were somewhat qui-
crete) to wood ties on ballast (at grade and elevated track). eter when new. At least one subway station was retrofitted as
Light rail lines also have areas of direct pour concrete fixa- a means of noise reduction. However, the noise level was not
tion. In these cases, the rails are initially held in place every satisfactorily reduced in this station, even after the additional
6 ft with Pandrol clips and a steel beam tie. Then, the rails are wheel/rail smoothing, sound absorption, and barriers. Atten-
fully embedded in concrete with only gage face clearance left tion to this issue continues, because the root problem source
in the concrete. However, tracks with this installation method remains somewhat undefined.
show that the concrete can rupture prematurely near battered The eastern portion of the Market-Frankford (Blue) line
joints. has required significant rail head and gage face grinding to
For commuter track, both wood ties on ballast and booted remove corrugations (and associated noise) on tangents.
two-block concrete ties are used. The City Transit (Green) line has flange-bearing wheels
for special trackwork. The route has one nonflange bear-
ing frog with level points and wings. A depressed point
A3.6 LUBRICATION AND WHEEL SLIDE
frog was installed at one location, but immediate public
complaints resulted in replacement with a level style. Dy-
Rapid transit operations include up to 40-degree (150-foot
namic braking also tends to reduce noise by reducing wheel
radius) curves. Such curves are manually greased daily.
sliding.
SEPTA is hoping to improve flange grease controllability
and efficiency on these curves by installing through-holes on
the restraining rails, along with grease fittings and automatic A3.8 MAJOR CONCERNS AND ACTIONS
pumps.
On the commuter lines, most curves over 3 degrees SEPTA inherited a wide array of infrastructure from pre-
(1900-foot radius) have wayside flange lubricators. The ceding entities. This includes different track design stan-
commuter lines include 12-degree (480-foot radius) dards, different vehicle types, and different track gages.
curves near a regional station. This location formerly SEPTA also inherited problems resulting from deferred
caused excessive wheel and rail wear. Now liberal rail maintenance by previous railroads. At one point, over 600
greasing and 15 mph speed restrictions are used to mini- defective welds were found in track as a result of poor weld-
mize wear. ing practices. This number has steadily decreased as SEPTA
Slippery rails due to leaf residue in the fall months are a continues to put forth significant effort into improving track
major concern. In the fall, 60 to 80 percent of regional train maintenance.
delays are leaf-related. In 2002, this issue caused the delay of Similarly, the regional commuter lines were taken over
2,357 trains. Wheel slides due to rail contamination lead to in 1982 with immediate track geometry and rail condition
flat spots. Dynamic impacts due to these flats can damage the problems, requiring several years of continuous improve-
track, induce noise, and affect ride quality. ment of track geometry to achieve desired quality condi-
To mitigate the seasonal problem, SEPTA cleans the tions. Over the past 20 years, almost all tracks in the com-
track on the Norristown line, and on regional lines during muter rail system have been upgraded with continuously
their short, 3-hour overnight work window. This is done welded rail.
with both advanced techniques (former locomotives now Lubrication continues to be an area of development at
called "Gel Cars" with a 5,000-psi high-pressure washer and SEPTA. Rail wear issues primarily drive this effort.
traction gel applicators operating at 10 mph) and more tra- Although still employing manual track greasing in some
ditional methods, such as by applying sand with locomo- rapid transit locations, more advanced track-based systems
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are slowly being implemented. The next step in this process Wheel sliding and the resulting wheel flats are a major
is a trial installation of through-hole grease fittings on issue and problem, especially during the autumn season. Sev-
guardrails for flangeway lubrication. eral techniques have been applied to ease the problem, but
SEPTA has experienced infrequent derailments that fall the need for developing more effective technology to remove
into two categories: train handling (traction, braking, exces- rail contaminants is needed.
sive speed) and slow-speed flange climb (at more severe The cause of rail corrugation is still under investigation.
curves, yards, climbing switches, and sometimes soon after Both rail grinding and rail replacement have been conducted
re-profiling). to remove corrugation.
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APPENDIX A-4
WMATA
WMATA has a large degree of standardization. Only three To improve margins of safety, WMATA is considering a
car types have been used in the system's 35-year history: the design wheel profile change to a higher flange angle. How-
original Rohr cars are still in use, as well as Breda cars pur- ever, the system stability during such a transition is being
chased in the early 1980s and CAF cars recently delivered. carefully considered.
The Rohr cars have an Atchison/Rockwell suspension with The current standard rail is 115RE for new installation.
good curving performance. This type of car is deemed Head-hardened rail is installed on tight curves.
slightly more prone to hunting when trucks are worn. The
Breda cars have a longer wheel base (5 in. longer) than Rohr
cars, and a slightly stiffer primary suspension. Over time, the A4.2 WHEEL LIFE AND WHEEL TRUING
Breda cars have been involved in a few flange climb derail-
ments. The cars have approximately 13,200-pound maxi- WMATA wheels show a typical life of about 400,000 mi,
mum wheel loads and use 28-in. diameter wheels. (The or 4.5 years of operation. Between 3 and 5 re-profiling oper-
weight of the Breda is approximately 81,000 pounds.) ations are possible before reaching to the thin flange or thin
WMATA is a relatively new system compared to the other rim limits. As with every system, wheel flats can be a prob-
transit systems surveyed. Therefore, its track layout contains lem during the fall season each year. The autumn leaves are
fewer tight curves. The tightest curve in WMATA has a a major cause of wheel re-profiling. This has periodically
radius of 250 ft (23 degrees). An extensive preventative overloaded the wheel shops, requiring a few weeks of over-
maintenance program results in good ride and operational time labor to remove flats.
qualities. However, a few recent incidents of flange climb WMATA has two types of wheel-re-profiling machines:
derailments have raised concerns related to wheel profiles milling and lathe. Shop personnel report significantly
and track gage.
smoother finishes with the lathe machine. Consequently,
after the use of the milling type machine, WMATA wheels
get a minimal pass as the final step of re-profiling (known as
A4.1 WHEEL AND RAIL PROFILES
the "air cut," where no significant material is removed).
Perhaps more importantly, all wheels are now manually
The original WMATA cars were supplied with cylindrical
wheel profiles that resulted in excessive wheel and rail wear. lubricated immediately after re-profiling.
To reduce the excessive wear, a field experiment was per- Wheel diameter tolerances after re-profiling are 1/16 in.
formed during 1978 and 1979 to select a wheel profile with within the axle, 1/4 in. axle-to-axle in the same truck, and 1/2
better wear performance. The wheels in 12 trucks of three in. truck-to-truck in the same car.
Rohr car series were machined to various wheel profiles. WMATA believes that most wheels are trued at least once
Wear rates were analyzed. This test led to the adoption of the per year as a result of its "no flat" policy.
"British Worn" profile as WMATA's standard wheel shape.
This profile has a flange angle of 63 degrees.
In recent years, there have been several incidences of A4.3 RAIL LIFE AND RAIL GRINDING
flange climb derailment--most of them at yard switches.
Generally, these derailments were caused by multiple factors. Generally, tangent track and most low rails at curves on
Among the derailment factors, observations included newly this system have retained the original rails. Rail replace-
re-profiled wheels and dry rails. Under such conditions, the ment is performed more frequently on sharper curves.
friction coefficient between wheel and rail can be quite high. WMATA allows 1/2 in. of gage face wear. Thus, the tran-
In combination with WMATA's low flange angle, the L/V sit system reports that curves greater than 7.5 degrees
ratio limit before precipitating a flange climb derailment can (760-foot radius) last 3 to 5 years, and frogs last about
be considerably low. Also, wheels with low flange angles 8 years. Rails are not generally re-laid due to the extra effort
have less tolerance to any unexpected track irregularities. required.
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An outside contractor performs grinding annually. Loca- A4.6 LUBRICATION AND WHEEL SLIDE
tions for rail grinding are specified based on subjective eval-
uations of ride quality and noise. No lubrication is performed on mainline track, but some
traditional wayside flange lubricators are used in yard tracks
and guard rails. Past trials of both on-board stick lubricators
A4.4 TRACK STANDARDS and wayside top-of-rail friction modifiers proved to reduce
noise but caused wheel slide and were hard to maintain.
Maximum speed on the system is 75 mph, but currently it Therefore operations precluded the application of lubrication
is restricted to 59 mph for energy conservation and equip- on mainline.
ment longevity. As with other lines, leaves are a problem in the fall caus-
Allowable track gage, alignment, profile, and cross level ing excessive wheel flats. WMATA does not attempt to clean
deviations tend to make up one-third to one-half of the toler- rails; rather operating speeds are reduced and selected safety
ances found in FRA rules for Class 3 (60 mph) track. stops are used to reduce the effects of leaves.
Designed track gage also varies by curvature:
· 1/4 in. tight on mainline tangent to 4-degree curves.
· Standard on 4- to 16-degree curves. A4.7 MAJOR CONCERNS AND ACTIONS
· 1/2 in. wide above 16-degree curves.
Major issues for WMATA relative to wheel/rail profiles
· 3/4 in. wide above 16-degree curves with restrained rail.
are the following:
WMATA is installing guardrails on all switches corre-
· Improving wheel flange angle to reduce flange climb
sponding to less than a 500-foot radius (11.5-degree). Also,
derailment.
curves with less than a 800-foot radius (7.2-degree) are
· Careful planning for a smooth transition to a new wheel
equipped with guardrails. Guardrail clearance is set to 1 7/8 in.
profile.
The sharpest yard curve is 250 ft in radius (23 degrees).
· Optimizing gage distance on curves to improve vehicle
The sharpest mainline track curve is 755 ft in radius (7.6
curving and reduce wear.
degrees). Secondary and yard tracks are designed to 4.5 in.
· Searching for more effective techniques to deal with the
underbalance operation. Tie plates are standard 1:40.
leaf residue problem.
WMATA has attributed some flange climbs on special track-
· Applying resilient rail/tie isolators to reduce noise.
work to the lack of rail cant.
· Investigating acceptable lubrication practices.
· Maintaining a high level of ride quality. Infrequent and
A4.5 FIXATION METHODS somewhat transient hunting has been known to occur at
certain places on the system, which seems to be driven
All WMATA surface tracks are crosstie on ballast con- by specific combinations of vehicle and track (including
struction. However, both elevated and underground tracks prevailing grade). As the vehicles age, this hunting sit-
have direct fixation via resilient (rubber/steel tie pad) fasten- uation may further deteriorate. If so, it is likely that a
ers. Stiff (250-kip/in.) and softer (150-kip/in.) fasteners have specific study of the cause/effect mechanisms will be
been tried, with the softer versions preferred. required.
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APPENDIX A-5
CTA
CTA operates the city's rapid transit system. Currently The combination of these two factors could considerably
225 mi of track are in service on seven lines, including about reduce the L/V limit for flange climb on the tight curve that
25 mi of subway. has a tendency to generate high lateral forces. Subsequently,
CTA uses four series of 48-foot long passenger cars simi- a guardrail was installed and the lubricator has been regularly
lar in construction. These cars have a light axle load (19,200 inspected.
pounds fully loaded) compared to other subway systems The current rail profile at CTA is 115RE. However,
(around 26,000 pounds). short sections of older 90- and 100-lb/yd rail are still in
All but the oldest CTA cars use a large kingpin (6-in. use. Although starting with a crown radius, these rails are
diameter and 14-in. length) allowing only rotational freedom maintained to a flat head. Rail wear patterns identified in
about a vertical axis. All but the oldest cars have Wegmann the field indicate that this wheel/rail combination has a
style trucks, which equalize weight distribution by primary rather wide contact band at wheel tread and rail head
spring deflection and allowing the truck center plate to warp. region.
Routine car inspections are conducted at 6,000 mi or 90
days. Partial overhauls are conducted at one-quarter life, or
about every 7 years. Complete overhauls are performed at A5.2 WHEEL LIFE AND WHEEL
half life, or about 12 to 14 years. RE-PROFILING
CTA has not experienced flange wear problems using the
A5.1 WHEEL AND RAIL PROFILES AAR cylindrical tread contour. The wheel life is not actually
tracked in routine maintenance. Thus, the current wheel life
CTA uses 28-in. diameter wheels with the AAR narrow is unknown, but it was estimated as longer than 3 years and
flange cylindrical tread profile with a flange angle of close to perhaps as much as 6 to 7 years.
68 degrees. This profile was adopted by CTA in the 1930s to CTA estimates that almost all wheel profile maintenance
eliminate vehicle hunting that occurred at 60 to 80 mph on
is done due to tread flat spots, mostly induced by operational
high-speed, interurban cars.
causes such as braking, acceleration, and curving. Some flat
Based on CTA's staff statement during the survey, this
spots may be caused by rail contamination, such as falling
cylindrical profile has been performing well, likely because
leaves. Subjective conditions for removing flats are mainly
of two major factors:
based on operator or public complaints. Since this is not a
dimensional criterion, CTA personnel believe that a few flat
· A high percentage of tangent track.
· A lighter axle load compared to other rapid transit. spots approaching 2 in. in diameter can be found on the sys-
tem. Occasionally, a wheel is re-profiled because it has
CTA personnel recalled no mainline derailments in recent exceeded the high flange limit. Wheel tread hollowing is
history. At the 54th Street yard, a few wheel-climb derail- rarely seen during wheel maintenance.
ments have occurred in the past decade. These occurred at a Wheel re-profiling is performed on lathe-style machines
100-foot radius curve installed without a guardrail. The track only at the Skokie shop and one Blue Line shop. CTA finds
worked well for 3 years, then an alignment of two factors that this type of machine holds diameter variations on
caused a few climbs on newly re-profiled wheels: an axle much closer than a cutting head machine
(within 0.005 to 0.010 in. from left to right wheel after
· Acceptance of a new wheel re-profiling machine at the re-profiling).
shop that might have increased the wheel surface rough- The current wheel diameter tolerances allowed after
ness after re-profiling. re-profiling are 3/64 in. within an axle (0.046 in.), 1 in. axle-
· Malfunction of the curve lubricator on this section of to-axle in the same truck, and 1-in. truck-to-truck within the
track. same car (i.e., using the same rule as above).
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A5.3 RAIL LIFE AND RAIL GRINDING segments on either side of steel structures or bridges. Longer
switch ties and closer-than-normal tie spacing were applied to
Rails on tangent track and shallow curves have a relatively create a stiffer support between the standard ballasted track
long life, perhaps 50 years. Further, rails last about 15 years and the elevated track.
even on the very tight curves at the corners of Chicago's CTA has noticed instances of the high rail lifting in loca-
famous Loop (89-foot radius). This is likely due to the low tions that have greater than a 1 7/8-in. flangeway in a guarded
wheel loads, local rail lubrication, and low speeds (15 mph) curve. The greater flangeway width allowed higher lateral
allowed around the curves in the Loop. force against the high rail, and, consequently, the rail lifted
CTA does not experience rail shelling because of light axle from the tie plates. The rail was retained with standard cut
loading. Rail grinding is performed using a "rail smoother" spikes. The flangeway width was corrected to 1 7/8 in. and
that uses flat stones to grind a surface parallel to the top of the problem was corrected.
the tie plates. The light grinding (using 8 to 10 grinder
passes) is used on the whole system once a year to smooth
corrugations and other imperfections. A5.6 LUBRICATION AND WHEEL SLIDE
New rails are installed with the original crown, and CTA
smoothes the head about 1 year after installation. Typically CTA uses both traditional wayside flange lubricators and
after such smoothing, the rail needs no maintenance for a few trial wayside, top-of-rail friction modifier installations.
another 4 years. Elevated track may require smoothing Lubricators are installed on the curves with a radius of less
slightly more often. than 500 ft. CTA track design personnel expressed interest in
learning how different lubrication methods affect lateral
forces.
A5.4 TRACK STANDARDS The close spacing of trains on the system prevents the use
of a hi-rail vehicle lubricator. No onboard rail lubrication is
Maximum speed on the CTA system today is 55 mph, with
used or planned at this time. An earlier field trial of onboard
15 mph limits on the tight (90-foot radius) Loop curves. The
solid stick flange lubricants (using the Skokie Swift Line)
CTA track is generally designed to FRA Class 3 track geom-
was unsatisfactory.
etry standards, but specifically applying the shorter 31-foot
Regarding seasonal wheel slides, the Skokie Swift (Yel-
criteria. Also, CTA designs curves for a maximum of 4.5 in.
low Line) and the Brown Line near the end of the line on bal-
of underbalance operation.
lasted track have received noise complaints due to wheel
Track geometry is not measured regularly. A contractor
flats. These flats are deemed to be related to leaf residue and
was hired to measure the system in the early 1990s, but track
geometry measurement has not been conducted since then. resulting wheel slips. Removal of wheel flats is the active
Visual inspections are performed twice a week by track program to mitigate these complaints.
walkers. No out-of-face, ultrasonic rail head inspections are Other lines of the CTA system generally operate without
performed, but ultrasonic bolthole/joint inspections are reg- leaf problems, likely due to two factors:
ularly scheduled.
All curves with a radius of less than 500 ft have guardrails, · Mostly underground, elevated, or freeway-median oper-
with a 1 7/8-in. flangeway clearance. The guardrail continues ating away from vegetation.
10 ft before and after the curve. Designed track gage is the · Seven-day, 24-hour operations.
standard 56.5 in., except an additional 1/4-in. of width on
curves tighter than a 125 ft radius. Maintenance is performed For these reasons, CTA does not have a rail-cleaning
when the gage exceeds 1 in. in width. program.
A5.5 FIXATION METHODS A5.7 NOISE
On elevated track, rails are fixed to full width wood ties. Due to the extensive curve lubrication employed and cur-
In the subway, CTA employs mostly wood half-ties in con- rent vehicle designs (lighter weights and relatively soft sus-
crete. Some subway rails are held with coach screws, others pensions), CTA has reduced rail/wheel noise considerably in
with resilient fasteners. In and near the O'Hare Station, the the past 25 years. CTA's solid wheels are now equipped with
track is directly fixed in concrete with resilient fasteners. damper rings as shown in Figure A5-1, which has signifi-
CTA's surface tracks and a small amount of tunnel track are cantly reduced the free vibration of the plate.
ballasted, with the use of spikes gradually being phased out Although the elevated structures remain rather noisy, fur-
in favor of clips. ther noise reductions are largely deemed impossible without
To minimize dynamic car responses due to track stiffness reengineered support structures, since the steel girders are
variation at bridge approaches, CTA designed special 100-foot very effective noise amplifiers.
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A5.8 MAJOR CONCERNS AND ACTIONS
CTA's wheel/rail profile maintenance focuses on keeping
the wheels round and the rails smooth. Satisfactory vehicle
designs have been proven over long periods, and CTA has no
plans to change what works. Track installations and lubrica-
tion methods continue to evolve gradually, with a conserva-
tive policy toward trial installations.
Past problems have included the following:
· Vehicle hunting--improved by employing a cylindrical
profile years ago.
· Curve squeal/screech--improved by slightly soft pri-
mary suspension trucks, light vehicles, rail lubrications,
and lowered operating speeds.
· Slow-speed yard derailments--leading to greater atten-
tion on guardrail placement and lubricator maintenance.
CTA track designers would also like a computer program that
Figure A5-1. Steel damper on CTA wheels: The steel allows input of design parameters (e.g., curve radius, operating
damper fits snugly into a groove on the field-side plate and speed, underbalance, lubrication presence, profile) and pro-
reduces ringing considerably. duces the expected lateral force ranges generated by the wheels.
