Track Design Handbook for Light Rail Transit, Second Edition (2012) / Chapter Skim
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From page 11... ...
2-i Chapter 2 -- Light Rail Transit Vehicles Table of Contents 2.1 INTRODUCTION 2-1 2.1.1 State-of-the-Art for Light Rail Vehicles 2-1 2.1.2 Vehicle/Trackway Interface 2-2 2.2 LIGHT RAIL VEHICLE DESIGN CHARACTERISTICS 2-3 2.2.1 Introduction 2-3 2.2.2 Vehicle Design 2-4 2.2.2.1 Unidirectional/Bi-Directional 2-4 2.2.2.2 Non-Articulated/Articulated 2-5 2.2.2.3 High-Floor/Low-Floor LRVs 2-7 2.2.2.3.1 Introduction 2-7 2.2.2.3.2 Low-Floor Cars -- General 2-8 2.2.2.3.3 Low-Floor Car Truck Design 2-8 2.2.2.4 Carbody Strength, Crashworthiness, and Mass 2-9 2.2.2.4.1 Introduction 2-9 2.2.2.4.2 Crash Energy Management 2-10 2.2.2.4.3 LRV Bumpers 2-11 2.2.2.4.4 Vehicle Mass 2-11 2.3 VEHICLE CLEARANCES 2-14 2.3.1 Vehicle Clearance Envelopes 2-14 2.3.2 Vehicle Static Outline 2-15 2.3.2.1 Vehicle Length 2-16 2.3.2.2 Distance between Truck Centers 2-16 2.3.2.3 Distance between End Truck and Anticlimber or Bumper 2-16 2.3.2.4 Carbody Width 2-17 2.3.2.5 Carbody End Taper 2-17 2.3.2.6 Other Static Clearance Factors 2-18 2.3.3 Vehicle Dynamic Envelope/Outline 2-19 2.3.3.1 Vehicle Components Related to Vehicle Dynamic Envelope 2-22 2.3.3.2 Track Components Related to Vehicle Dynamic Envelope 2-22 2.3.3.3 Vehicle Clearance to Wayside Obstructions and Other Tracks 2-22 2.3.3.4 Platform Clearances 2-23 2.3.3.5 Pantograph Height Positions 2-23 2.4 VEHICLE-TRACK GEOMETRY 2-24 2.4.1 Horizontal Curvature -- Minimum Turning Radius of Vehicle 2-25 2.4.2 Vertical Curvature -- Minimum Sag and Crest Curves 2-25 2.4.3 Combination Conditions of Horizontal and Vertical Curvature 2-25 2.4.4 Vertical Alignment -- Maximum Grades 2-26 2.4.5 Maximum Allowable Track Twist 2-27 2.4.6 Light Rail Vehicle Ride Quality 2-29 2.4.6.1 Vehicle Natural Frequency as a Factor in Ride Comfort 2-29 2.4.6.2 Track Geometrics as a Factor in Ride Comfort 2-29
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From page 12... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-ii 2.5 VEHICLE STRUCTURAL LOADS 2-30 2.5.1 Static Vertical Loads 2-30 2.5.2 Wheel Loading Tolerance (Car Level) 2-30 2.5.3 Wheel Loading at Maximum Stationary Superelevation 2-30 2.5.4 Unsprung Mass 2-30 2.5.5 Truck Design 2-31 2.5.5.1 Motorized Trucks 2-31 2.5.5.2 Non-Motorized (Trailer)
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From page 13... ...
Light Rail Transit Vehicles 2-iii 2.6.4 Maintenance of the Wheel/Rail Interface 2-51 2.6.5 Matching Wheel and Rail Profiles 2-51 2.6.6 Wheel Tread Widths and Flangeways at Frogs 2-53 2.7 RESILIENT WHEELS 2-53 2.8 ON-BOARD VEHICLE WHEEL/RAIL LUBRICATION 2-55 2.9 VEHICLES AND STATIONS -- ADA REQUIREMENTS 2-56 2.10 REFERENCES 2-57 List of Figures Figure 2.3.1 Three-section 70% low-floor LRV in an 82-foot [25 meter] radius curve 2-18 Figure 2.3.2 Typical LRV dynamic envelope 2-21 Figure 2.5.1 Kinki Sharyo power truck for 70% LRV 2-32 Figure 2.5.2 Siemens power truck for a Combino 100% low-floor narrow gauge LRV 2-33 Figure 2.5.3 Bombardier Flexity Outlook power truck for 100% low-floor LRV 2-33 Figure 2.5.4 Kinki Sharyo trailer truck for 70% low-floor LRV 2-34 Figure 2.5.5 Kinki Sharyo cranked axle for low-floor LRV trailer truck 2-35 Figure 2.6.1 Candidate initial LRV wheel profile 2-45 Figure 2.6.2 Compromise wheel for Karlsruhe tram-train 2-50 Figure 2.6.3 Wheel-rail interface 2-52 Figure 2.7.1 Bo84 wheels used by NJ Transit 2-55 List of Tables Table 2.2.1 Relative mass of 100% vs.
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From page 14... ...
1-2 CHAPTER 2 -- LIGHT RAIL TRANSIT VEHICLES 2.1 INTRODUCTION The light rail transit vehicle ("light rail vehicle" or "LRV" for short) is arguably the most publically prominent feature of any LRT system.
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From page 15... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-2 that make even larger LRVs more suitable for operation in areas with large volumes of pedestrians and motor vehicles. • Articulated streetcar vehicles, with the trucks semi-rigidly attached to the carbody rather than swiveling relative to the carbody.
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From page 16... ...
Light Rail Transit Vehicles 2-3 • Lateral Vehicle Forces on the Track - Maximum lateral forces resulting from all speed and curvature combinations • Dynamic Vehicle Forces on the Track - Impact of car and truck natural frequencies - Impact of wheel flats or damaged wheels It is essential that the track designer, the vehicle designer, and the designers of systems such as signals, catenary, etc., coordinate and cooperate to achieve compatibility between the LRT system components under all operating conditions. These interactions can be facilitated by generating a comprehensive design criteria manual for any new LRT system and keeping it updated with "as-built" information as the project is developed, constructed, and operated.
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From page 17... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-4 • Suspension characteristics • Performance (acceleration, speed, and braking) • Wheel diameter and wheel contour • Wheel gauge These characteristics must be considered in the design of both the vehicle and the track structure.
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From page 18... ...
Light Rail Transit Vehicles 2-5 • Single-end vehicles that have doors on both sides can be coupled back-to-back resulting in a double-end train. • The choice of single-end versus double-end vehicles may have an impact on how yard and shop facilities are laid out.
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From page 19... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-6 functionally very similar to high-floor, articulated LRVs of today. The objective of this evolution in vehicle design was to maximize not only passenger capacity but also the number of passengers carried per operating employee since labor costs, then as now, were a high percentage of the cost of transit operation.
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From page 20... ...
Light Rail Transit Vehicles 2-7 could not be economically lengthened. Longer vehicles can affect other infrastructure and systems as well, particularly the layout of equipment within the light rail vehicle maintenance shop.
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From page 21... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-8 [0.9 meter] higher.
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From page 22... ...
Light Rail Transit Vehicles 2-9 floor would be lower than the elevation of solid axles. The usual resolution is to use trucks that do not have conventional solid axles extending from wheel to wheel.
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From page 23... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-10 its mass, with the result that new transit cars were much heavier than their predecessors. This extra weight had impacts on power consumption, structure design, and track design.
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From page 24... ...
Light Rail Transit Vehicles 2-11 unnecessarily increase the procurement costs are under consideration. Whether those changes will be adopted in whole or part cannot be predicted, and rail transit design practitioners must therefore keep current with evolving best practices.
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From page 25... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-12 Table 2.2.2 shows some of the characteristics of modern light rail vehicles operating in North American cities as of 2010. The table is not intended to be a comprehensive reference of every vehicle or every system now operating but rather an illustration of the rather wide array of vehicles that a track designer might encounter on any given project.
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From page 26... ...
Light Rail Transit Vehicles 2-13 Table 2.2.2 Light rail vehicle characteristics matrix (2010 data) CITY Carbuilder/Model DELIVERY YEAR WEIGHT AW0 lbs MAXIMUM WHEEL LOAD lbs LENGTH Feet CARBODY CONFIGURATION FLOOR LEVEL 1 Baltimore ABB 1989/1995 108,000 12,000 95 6-axle 2-carbody High 2 Boston KS Breda 1982 2000 85,000 86,300 9,350 9,500 74 74 6-axle 2-carbody High 50% Low 3 Buffalo Tokyu 1985 71,000 11,000 66'-10" 4-axle 1-carbody High 4 Calgary Siemens SD 160 1999/2008 89,600 9,800 81'5" 6-axle 2 carbody High 5 Charlotte Siemens S 70 2004/2008 96,800 10,700 93'6" 6 axle 3 carbody 70% low 6 Cleveland Breda 1982 91,300 9,800 80' 6-axle 2-carbody High 7 Dallas KS 1 KS 2 1998 2007 108,000 140,000 11,600 15,176 92'6" 123'6" 6-axle 2-carbody 8-axle 3-carbody High Low 8 Denver Siemens SD 100 Siemens SD 160 1995 2008 88,000 9,650 81'6" 6-axle 2-carbody 6-axle 2-carbody High 9 Edmonton Duewag U 2 Siemens SD-160 1982 2009 67,300 91,700 7,900 9,960 79'8" 81'4" 6 axle 2-carbody 6-axle 2-carbody High High 10 Houston Siemens S 70 2004 98,500 10,950 96'6" 6-axle 3-carbody 70% low 11 Los Angeles Nippon Siemens SD100 Siemens P2000 Breda 2550 1992 1993 1999 2008 98,000 98,000 89,000 10,700 10,700 9,970 89' 89' 90' 6-axle 2-carbody 6-axle 2-carbody 6-axle 2-carbody 6-axle 2-carbody High High High High 12 Minneapolis BBD Flexity 2004 99,180 10,940 94' 6 axle 3-carbody 70% low 13 New Jersey Kinki Sharyo BBD (DMU)
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From page 27... ...
Track Design Handbook for Light Rail Transit, Second Edition 41-2 Table 2.2.2 Light rail vehicle characteristics matrix (2010 data) (continued)
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From page 28... ...
Light Rail Transit Vehicles 2-15 build cars to any dimension, it is usually more economical to choose vehicles that are already in production or have at least been engineered. Therefore, the facility designer of a new system should establish a composite vehicle clearance envelope that accommodates vehicles from several manufacturers to maximize competitive bidding and then design the system to accommodate those clearances.
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From page 29... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-16 2.3.2.1 Vehicle Length When considering the length of a light rail vehicle, it is important to distinguish between the actual length of the carbody and its length over the coupler faces as follows: • Over Coupler Face -- The coupler is the connection between LRVs that operate together. It extends beyond the front of the car structure.
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From page 30... ...
Light Rail Transit Vehicles 2-17 2.3.2.4 Carbody Width The width of the LRV carbody is determined by several factors: • In the case of any LRV that will be operating in mixed traffic in a street, it generally should comply with the legal maximum widths for motor vehicles. There can be some latitude on this since, unlike a large rubber-tired vehicle such as a truck, the path of the LRV is absolutely predictable.
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From page 31... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-18 Figure 2.3.1 Three-section 70% low-floor LRV in an 82-foot [25-meter] radius curve The ideal situation clearance in curves on a double-track route is to design the end taper and select the truck centers and pivot point locations so as to make the mid-ordinate and endoverhang clearances at equal distances from the track centerline.
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From page 32... ...
Light Rail Transit Vehicles 2-19 The geometric center of the plan view of a rail vehicle truck in curved track will not be coincident with the centerline of the track, but rather shifted some distance toward the inside of the curve. The magnitude of this shift will vary depending on the axle spacing of the truck, the radius of the curve, the lateral position of the truck relative to the rails, and any skew the truck may have assumed relative to the track.
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From page 33... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-20 but instead be addressed by the track designer as part of the track construction and maintenance tolerances. If the vehicle designer does include track factors in the VDE, that fact needs to be clearly documented.
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From page 34... ...
Light Rail Transit Vehicles 2-21 Figure 2.3.2 Typical LRV dynamic envelope
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From page 35... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-22 2.3.3.1 Vehicle Components Related to Vehicle Dynamic Envelope The vehicle dynamic envelope is influenced by both the as-fabricated characteristics of the vehicle, particularly its suspension system, and possible wear and/or failure of vehicle subassemblies. These factors include • Primary/secondary suspension systems • Maximum roll/lean/sway • Maximum lean due to total failure of all truck components • Wheel tread and flange wear Air springs (also known as air bags)
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From page 36... ...
Light Rail Transit Vehicles 2-23 vehicle dynamic envelopes from adjacent tracks obviously must be avoided. The resulting requirements will dictate minimum track centers and running clearances for tangent and curved track, including construction and maintenance tolerances as input to the track alignment calculations.
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From page 37... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-24 car with the pantograph locked down is typically only of concern in the design of maintenance shop infrastructure, such as the entrance door to a paint booth, where the LRV would usually be pushed or towed by other equipment. Lock-down clearances would only be a consideration along revenue service track if the LRV has "off-wire" operating capability.
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From page 38... ...
Light Rail Transit Vehicles 2-25 2.4.1 Horizontal Curvature -- Minimum Turning Radius of Vehicle The minimum turning radius is the smallest horizontal radius that the LRV can negotiate. In some cases, the value may be different for a single LRV versus two or more coupled into a train or for a fully loaded LRV versus an empty one.
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From page 39... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-26 with potential LRV suppliers to establish mutually agreeable limits. The following is a typical example from one vehicle specification: Reverse vertical curve: A two-vehicle consist shall be capable of negotiating a reverse vertical curve section involving: first, a crest of 250 m [820 feet]
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From page 40... ...
Light Rail Transit Vehicles 2-27 Slippage may result in rail burns during both acceleration and braking and wheel flats during braking. Light rail vehicles have always been equipped with sanders, activated by the operator to drop dry sand on the rail and thereby increase friction between wheel and rail.
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From page 41... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-28 specification for the maximum wheel unloading when one wheel is leaving the horizontal plane -- such as when being lifted by the outer rail on spiral curve with superelevation: Lifting or lowering any wheel on a truck 38 mm (1.5 inches) shall not cause the load to change on any wheel of that truck by more than 50% with the vehicle on level tangent track and under an AW0 load.
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From page 42... ...
Light Rail Transit Vehicles 2-29 requirements. If jump frogs are proposed on an LRT project, that fact should be clearly identified in the vehicle procurement documents.
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From page 43... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-30 2.5 VEHICLE STRUCTURAL LOADS 2.5.1 Static Vertical Loads ASME RT-1[8] defines light rail vehicle weights as follows: • AW0: Empty load: the weight of the vehicle ready to run with all mounted components, including full operating reserves of lubricants, windshield fluid, etc., but without crew and passenger load.
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From page 44... ...
Light Rail Transit Vehicles 2-31 secondary suspension systems. The use of resilient wheels theoretically reduces unsprung mass to only the weight of the tire; however, the elastomeric elements of resilient wheels still need to be fairly stiff so as to keep the tire both circular and concentric with the axle.
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From page 45... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-32 The power trucks beneath 100% low-floor cars are much more sophisticated since they require room for the low-floor passenger cabin to pass between the wheels and truck frame. Figure 2.5.2 illustrates an outside frame truck design for narrow gauge track with the motors mounted longitudinally outboard of and between the wheels.
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From page 46... ...
Light Rail Transit Vehicles 2-33 Figure 2.5.2 Siemens power truck for a Combino 100% low-floor narrow gauge LRV Figure 2.5.3 Bombardier Flexity Outlook power truck for 100% low-floor LRV
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From page 47... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-34 Figure 2.5.4 Kinki Sharyo trailer truck for 70% low-floor LRV 2.5.5.2 Non-Motorized (Trailer) Trucks Non-motorized trucks are typically located under the articulation joints of LRVs.
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From page 48... ...
Light Rail Transit Vehicles 2-35 Figure 2.5.5 Kinki Sharyo cranked axle for low-floor LRV trailer truck 2.5.5.3 Load Leveling Both motorized trucks and trailer trucks typically include air bags as the secondary suspension. Leveling valves installed on the bolster sense changes in pressure between the air bags due to increases or decreases in the passenger loads and automatically inflate or deflate the air bags to restore the car floor level at the predetermined location in compliance with ADAAG.
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From page 49... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-36 2.5.5.4 Inboard versus Outboard Bearing Trucks In its simplest form, a truck has two axles that are held parallel to each other by a truck frame. The points at which the frame is supported by the axles are called bearings.
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From page 50... ...
Light Rail Transit Vehicles 2-37 rely on the contact between the outer rail and wheel to accept all curving forces. Therefore, European carbuilders and other international carbuilders schooled in European practice do not typically expect there will be any force acting against the back of the wheel from a restraining rail.
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From page 51... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-38 2.5.6.3 Load Weight If the LRV has a load weight function, the acceleration and deceleration forces will be increased at car loadings above AW0 to some maximum loading value. These values should be defined to establish maximum longitudinal track force.
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From page 52... ...
Light Rail Transit Vehicles 2-39 The following formula is a sample computation of the longitudinal force (F) on the track created by a three-car train during emergency braking and using a 0.5 adhesion coefficient leading to a deceleration rate (d)
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From page 53... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-40 produce conditions where the wheel climbs over the rail head. The design of related friction surfaces should be such that the friction factor remains constant as service life increases.
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From page 54... ...
Light Rail Transit Vehicles 2-41 • A new system that will share part or all of its tracks with a freight railroad operation. In such cases, there is usually very little opportunity to change anything, and it may be necessary to default to Association of American Railroads (AAR)
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From page 55... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-42 necessary in railroad work because the acceptable maintenance tolerances for both track and wheel mounting are relatively large. In contrast, rail transit fleet sizes and track miles are both much smaller than they are for railroads, and it is somewhat easier to achieve tighter maintenance tolerances.
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From page 56... ...
Light Rail Transit Vehicles 2-43 TCRP Report 71: Track-Related Research -- Volume 3: Exothermic Welding of Heavy Electrical Cables to Rail, Applicability of AREMA Track Recommended Practices for Transit Agencies (prepared under TCRP Project D-7) addresses many issues relevant to the interface between LRT track and LRV wheel sets that are not covered by AREMA.
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From page 57... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-44 wheel and rail profile is less than 0.5 millimeters [0.02 inches] at the center of the rail (in singlepoint contact)
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From page 58... ...
Light Rail Transit Vehicles 2-45 tread that lies below the plane of the top of rail. On the field side of the concave worn tread, the wheel taper will actually be negative.
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From page 59... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-46 The paragraphs that follow describe some of the issues that must be considered when selecting or developing a wheel profile for light rail transit. 2.6.3.2.1 Tread Conicity Wheel treads virtually always have a conical taper when new (usually 1:20)
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From page 60... ...
Light Rail Transit Vehicles 2-47 AAR-1B wheel and transit wheels of similar design have Nadal Values of about 1.1, indicating a much reduced tendency to climb the rail and hence a greater margin of safety against derailment. To be fully effective, the 75-degree flange angle should be constant (i.e., not part of a curved surface)
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From page 61... ...
Track Design Handbook for Light Rail Transit, Second Edition 84-2 2.6.3.2.7 Flange Thickness Typically, the flange thickness -- the horizontal dimension from the projected vertical back face of the wheel to the gauging point on the front of the flange -- should be about 7/8 to 1 inch [22 to 25 mm]
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From page 62... ...
Light Rail Transit Vehicles 94-2 been made on several transit properties operating 70% low-floor cars were confirmed.[16] As a result of this accelerated wear, it is generally necessary to reprofile IRWs more frequently and replace the resilient wheel tires more often than on solid axle wheel sets.
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From page 63... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-50 Figure 2.6.2 Compromise wheel for Karlsruhe tram-train (all dimensions in millimeters) No tram-train systems have been constructed in North America, although DMU operations in southern New Jersey and Austin, Texas, have some tram-train characteristics.
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From page 64... ...
Light Rail Transit Vehicles 2-51 2.6.4 Maintenance of the Wheel/Rail Interface When the first edition of the Track Design Handbook for Light Rail Transit was published, there had been relatively little investigation into the rail/wheel interaction under transit vehicle loadings. Since that time, there has been a good deal of investigation under the auspices of TCRP Project D-7, with the results published as a series of volumes collectively known as TCRP Report 71.
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From page 65... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-52 As with wheel profiles, the majority of the research and development work regarding rail head profiles and rail profile grinding has been undertaken by and for the railroad industry. While the transit industry can also benefit from this research, readers are cautioned that recommendations for heavy haul railroads are very often less than entirely applicable to the transit industry.
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From page 66... ...
Light Rail Transit Vehicles 35-2 2.6.6 Wheel Tread Widths and Flangeways at Frogs When a wheel passes through a frog, the wheel tread must pass over the open throat of the intersecting flangeway. In an ordinary (not flange-bearing)
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From page 67... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-54 wheel load of approximately 6000 pounds [about 2700 kg] , which was sufficient under the relatively light PCC car.
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From page 68... ...
Light Rail Transit Vehicles 55-2 now possible without overstressing the wheel. One vendor reports commonly handling lateral forces of up to 45 kN [10,000 lb]
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From page 69... ...
Track Design Handbook for Light Rail Transit, Second Edition 2-56 initial method of on-board lubrication, solid stick lubricators held by spring pressure against the flange of the wheel, have generally been unsatisfactory. Several situations have changed that collectively show promise of creating an optimal method of getting friction modifiers to the locations that most need it: • Better lubricants and friction modifiers that are vastly superior to and more environmentally friendly than common mineral oils and greases.
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From page 70... ...
Light Rail Transit Vehicles 2-57 To properly address ADAAG requirements, designers will consider all dimensional tolerances of the platform/vehicle interface, such as • Track-to-platform clearances. • Vehicle-to-track clearances.
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From page 71... ...
Track Design Handbook for Light Rail Transit, Second Edition 85-2 [15]
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