The Design and Performance of the European Freight Wagon Standard Suspensions

In the paper we present the three most common European standard freight wagon suspensions. It is characteristic for the European suspensions that they are all primary suspensions without a bolster. The design and the function of their single elements are described. New results on the nature of dry friction and its influence on the damping characteristics are presented. Finally a few theoretical investigations of the dynamics of European freight wagons are surveyed with emphasis on the calculations of the critical speed. The results are compared with corresponding results for American wagons.

Forging the Way to a Better Axle

Historically, rail “axles” for the center truck of Low Floor Mass Transit Cars have been manufactured and supplied by European companies. The industry standard is a fabricated assembly comprised of forged ends welded to a structural steel center of various shapes. Several factors have enticed one domestic supplier to look for a better way to manufacture the axle in the United States. The word axle will be used in this paper, although technically the word “support” is more valid as an “axle” is assumed to rotate and this “support” does not. Currently, Penn Machine is producing its latest support, a one piece forged axle with the properties of the previous welded assembly. Many considerations, including material type, manufacturability, stress and deflection, weight, and dimensional fit, were made prior to approval of the final design. Because previous models were designed and manufactured overseas, European design criteria and materials had to be considered, and in some cases modified for the domestic market. The analysis approach began with a European calculation method. Additional analysis was performed to evaluate modifications. Finite Element Analysis was conducted to refine the design and to investigate material reducing options. The proposed paper outlines the design process used in bringing this new and innovative concept off the boards and into reality. It is the hope of the authors that others will recognize domestic opportunities by observance of the process used to create the new axle. To date, the new axle is being proposed for use on two new transit systems. The cars will be tested with the new axle to insure safety and performance.

A Preliminary Evaluation and Analysis of Technologies for Eliminating Railway Insulated Joints

This paper will investigate the feasibility of adopting innovative design concepts that could decrease the dependence on bonded insulated joints for railway track monitoring. First, the purpose of insulated joints and their historical usage are examined. Next, designs that utilize track circuits are discussed. This will be followed by a section on acoustic methods, reflectometry, and robotics.

Crashworthiness Requirements for Commuter Rail Passenger Seats

Occupant experiments using instrumented crash test dummies seated in commuter rail seats have been conducted on board full-scale impact tests of rail cars. The tests have been conducted using both conventional cars and cars modified to incorporate crash energy management (CEM). Test results indicate that an improved commuter seat design could significantly reduce occupant injuries associated with collisions of CEM railcars. Commuter seats built to specific crashworthiness design requirements can mitigate the increased severity of secondary impacts associated with CEM equipment. In a collision, the leading car or two in a CEM consist may have a more severe longitudinal crash pulse than the leading car in a conventional consist. The crash pulse associated with a leading CEM cab car results in a higher secondary impact velocity between the unrestrained occupant and the seat, when compared to a conventional cab car. This conclusion applies to both rear- and forward-facing occupants. As a result, the seat must absorb more energy, which may cause significant deformation of the seat back, preventing occupant compartmentalization. Compartmentalization is an occupant protection strategy that aims to: contain occupants between rows of seats, provide a ‘friendly’ impact surface, and prevent tertiary impacts with other objects. To compartmentalize occupants during a collision, seats must be relatively stiff. To limit the forces and accelerations associated with occupant injury, the seat must be compliant, absorbing the occupant’s kinetic energy as it deforms. The objective of seat design crashworthiness requirements is to strike a balance between the competing objectives of compartmentalization and minimizing occupant injury. Work is currently on-going to design, build and test a prototype 3-passenger commuter rail seat that will improve interior crashworthiness. The first step is to develop the design requirements, which are based on a head-on collision between a CEM cab car-led train and a CEM locomotive-led train. The seat design will be evaluated using quasi-static and dynamic finite element analysis. The occupant response will be evaluated using a collision dynamics model two rows of seats and three Hybrid III 50th percentile anthropomorphic test devices (ATDs). The seat design will be modified until the analytical models demonstrate that it meets the design requirements. Finally the prototype seat will be fabricated and tested quasi-statically and dynamically to ensure that the seat meets the design requirements. This paper describes the performance-based requirements that the prototype commuter rail seat must meet. Performance-based requirements include occupant compartmentalization, maximum allowable injury criteria, and maximum allowable permanent seat deformations. The paper also provides strategies for designing commuter seats that are better able to manage and dissipate the energy during a secondary impact. The paper describes computer models used to determine if the seats meet the design requirements.

Development of a Passenger Wheel Standard

The American Public Transit Association (APTA) is seeking to develop specifications to ensure that wheels used in passenger applications perform safely under the service conditions to which they are exposed. To this end, an approach has been developed which will address this need at two levels. First, a variant on the Association of American Railroads (AAR) S-660 standard [1] is proposed with loading requirements that more realistically represent typical conditions in passenger operations. This is considered a design standard and is to be applied to identify wheel designs not susceptible to fatigue cracking in the wheel plate and hub suitable for use by transit and commuter agencies. Second, an application standard (or more precisely, a recommended practice) has been conceived which is designed to assist transit agencies (or original equipment manufacturers) in the appropriate choice of an “approved” wheel design based on the expected service environment. This technique will identify wheel designs which, under normal operating conditions, should not result in thermal damage to the wheel tread.

Analysis of Lateral Track Strength for High Speed Rail

Recently the FRA has proposed a reduction in the maximum allowable net axle lateral load limit from the current 50 percent of static vertical axle load (NAL/V limit = 50%) to less than 40 percent depending, in part, on the basis of FRA’s lateral track strength model, TREDA. Such a reduction could indirectly result in limiting the maximum speed of high speed passenger trains to the equivalent of 7 inches (178 mm) cant deficiency. This paper reports on the author’s investigation of selected assumptions and calculations made in TREDA. Improvements to the model are recommended and a revised NAL/V relationship is proposed, derived from an independent analysis of the driving and resisting forces. Finally, a vehicle dynamic analysis is performed to determine how the author’s proposed revised NAL/V limit would affect 9-inch (229 mm) cant deficiency operation as the high speed rail industry is now considering.

A Crush Zone Design for an Existing Passenger Rail Cab Car

A Crash Energy Management (CEM) cab car crush zone design has been developed for retrofit onto an existing Budd M1 cab car. This design is to be used in the upcoming full-scale train-to-train test of a CEM consist impacting a standing freight consist of comparable weight. The cab car crush zone design is based upon the coach car crush zone design that has been previously developed and tested. The integrated system was developed after existing national and international CEM systems were reviewed. A detailed set of design requirements was then drafted, and preliminary designs of sub-assemblies were developed. The preliminary designs were analyzed using detailed large deformation finite element software. Performance of the cab car crush zone under ideal and non-ideal loading conditions was analyzed prior to development of the final design. The key components of the design include: a long stroke push-back coupler capable of accommodating the colliding locomotive coupler, a deformable anti-climber to manage the colliding interface interaction, an integrated end frame on which the deformable anti-climber is attached, a set of primary energy absorbers designed to crush in a controlled manner while absorbing the majority of the collision energy, and a survivable space for the operator which pushes back into an electrical closet. The cab car crush zone is designed to control both lateral and vertical vehicle motions that can promote lateral buckling of the train and override of the impacting equipment. The design is capable of managing the colliding interface interaction with a freight locomotive and passing crush back to successive crush zones. Detailed fabrication drawings have been developed and submitted to a fabrication shop. In addition, existing Budd M1 cars are being prepared to receive the retrofit components.

Real Time Monitoring of Vehicle/Track Interaction

ENSCO, Inc. has developed the next generation of real time Vehicle Track Interaction (V/TI) Monitoring system. The system provides continuous measurement of car body, truck motions and axle impacts. Software detects various acceleration events, tag them with GPS time and location information, and deliver the data to a central processing system through the latest Code Division Multiple Access (CDMA) wireless communication network. Upon delivery, the information is automatically tagged with milepost and subdivision or other geographic reference and loaded into an enterprise database management system. The data is available in near real time via the web on maps of the track and track infrastructure where users have the option of generating tabular reports or viewing the actual waveform of the acceleration event. In addition, the system offers real time pager and email notifications of predefined user events. This system automatically provides real time monitoring and detection of track profile and alignment problems, battered joints, rail-end mismatch, misaligned switches and damaged frogs. The information generated by this system helps railroads prioritize maintenance for these track anomalies that can cause equipment or lading damage. The location information picked up by the system allows railroads to navigate back to the track areas for follow up remedial actions or enhance track maintenance planning decisions. There are over 60 systems in operation on passenger and freight railroads. This paper will address the technology behind the monitoring, the events detected in the field, and how the system can be used to supplement traditional track inspection technologies.

A Novel Independent Train Localization Method Based on Multi-Sensor Fusion

Train localization system is a vital part of train control system. A novel independent train localization method based on multi-sensor fusion is proposed in this paper. In conventional train localization system, the position determination is dependent on the reference information source controlled by rail operator, such as track circuit and so on. In some new train localization systems on test[1][2][3][4], the localization methods based on Satellite Navigation are very popular, so that the system’s reliability and safety are put outside of the rail operators’ control actually. The localization method proposed in this paper uses inertial sensor gyrometer and conventional odometer, which is mounted on the locomotive’s driven axle. Gyrometer is used to measure train’s heading angular rate. And odometer is used to measure train’s velocity. Usually, the dead reckoning method independent of outside reference information is selected for these two sensors’ fusion. But an obvious disadvantage of this method is the position error is increasing linearly according to time, so that this method can not work independently. Therefore Satellite Navigation system is often used to restrict the increasing error to an acceptable range. The method proposed in this paper overcomes the disadvantage of dead reckoning. Because the rail route or train’s moving track is fixed, the route’s curvature-mile curve can be obtained. According to this curve it is obvious, in the area where route is straight, the curvature value is zero; in the area existing a turning, the value is not zero. DGPS equipment is mounted on the test train to get and record the position data on the test route. Then the curvature-mile curve can be calculated from these data. We use Hurst coefficient to get the characters of train track such as turning from the gyrometer and odometer’s data. By matching these characters and the known route’s curvature-mile curve, the train’s real-time position can be calculated. If the dual-direction communication channel such as GSM-R is available, virtual block or moving automatic block in train control system could be achieved. Details of this process are presented in this paper with some results to illustrate the effectiveness of the methods.

Dynamics Analysis of Self-Steering Railway Trucks for Assessing Curving Performance

The primary purpose of this study is to provide a qualitative analysis of the dynamics of the self-steering trucks that are commonly used for freight locomotives on improving curving performance and increasing adhesion in curves. Although there are a number of anecdotal statements on the ability of steerable trucks to reduce curving forces and increase adhesion in curves, to the best of our knowledge, there exists no study that provides a qualitative or quantitative analysis of these features of steerable trucks. Two aspects of locomotive trucks are essential for their ability to deliver small curving forces and high adhesion in curves. First, the ability to allow the axles to yaw sufficiently relative to the truck frames, such that they can hold a small angle of attack with the rail. Second, to provide sufficiently large longitudinal stiffness between the end axles and the axles and truck frame, in order to accommodate high adhesions. An equivalent stiffness analysis is used to show that the two steerable trucks that are considered for this study are far superior to conventional, three-axle, straight trucks in providing both a smaller angle of attack and a higher longitudinal stiffness for better curving and adhesion characteristics. The qualitative analysis of this study agrees with the experience the railroads have had with their self-steering trucks. The findings of this study indicate that self-steering trucks can result in lower lateral forces, accommodate tighter curves, and deliver higher adhesion in curves; without lowering the critical hunting speed of the locomotive. The results further show that the steering mechanism stiffness can have a large effect on the lateral, longitudinal, and yaw stiffness between the end axles; therefore, significantly lowering curving forces, and increasing adhesion and critical hunting speed of the truck.