Energy Savings With Reversible Thyristor Controlled Rectifier

The paper deals with energy savings in Traction Systems available with Thyristor Controlled Rectifiers (TCR) and Reversible TCR (RTCR). TCR provides active voltage control, RTCR in addition has power recuperation into AC line. The energy balance of the TCR and diode rectifier systems are calculated, including losses in the rails, car’s power train and friction losses. The TCR advantages over diode rectifiers: better voltage regulation and fault current limiting allow us to reduce the number of substations and increase their service life. Major energy savings are through recuperation back to AC line using RTCR, with additional savings through increased DC bus voltage. The estimated energy savings depending on the system parameters, train speed profile, etc. can be as high as 50%.

Thermal Analysis of Railroad Bearings: Effect of Wheel Heating

Catastrophic bearing failure is a major concern for the railroad industry because it can lead to costly train stoppages and even derailments. Excessive heat buildup within the bearing is one of the main factors that can warn of impending failure. A question is often raised regarding the transfer of heat from a wheel during braking and whether this can lead to false setouts. Therefore, this work was motivated by the need to understand and quantify the heat transfer paths to the tapered roller bearing within the railroad wheel assembly when wheel heating occurs. A series of experiments and finite element (FE) analyses were conducted in order to identify the different heat transfer mechanisms, with emphasis on radiation. The experimental setup consisted of a train axle with two wheels and bearings pressed onto their respective journals. One of the wheels was heated using an electric tape placed around the outside of the rim. A total of 32 thermocouples scattered throughout the heated wheel, the axle, and the bearing circumference measured the temperature distribution within the assembly. In order to quantify the heat radiated to the bearing, a second set of experiments was developed; these included, in addition to the axle and the wheel pair, a parabolic reflector that blocked body-to-body radiation to the bearing. The appropriate boundary conditions including ambient temperature, emissivity, and convection coefficient estimates were measured or calculated from the aforementioned experiments. The FE thermal analysis of the wheel assembly was performed using the ALGOR™ software. Experimental temperature data along the radius of the heated wheel, the bearing circumference, and at selected locations on the axle were compared to the results of the FE model to verify its accuracy. The results indicate that the effect of thermal radiation from a hot wheel on the cup temperature of the adjacent bearing is minimal when the wheel tread temperature is at 135°C (275°F), and does not exceed 17°C (31°F) when the wheel tread is at 315°C (600°F).

Evolutions in Railway Signaling: A “New Age” of Control?

The development of railroad signaling systems evolved with the need to provide interlocking between points and signals, and block working to keep trains a safe distance apart. Accordingly, the archetypal behavior of train control is summed up as providing (1) safe and efficient train movement by (2) the management of train routing and separation. This has been rudimentary since the advent of railway signaling and propagated in even the most contemporary of technologies today.

A Nonlinear Rail Vehicle Dynamics Computer Program SAMS/Rail: Part 1—Theory and Formulations

Accurate prediction of railroad vehicle performance requires detailed formulations of wheel-rail contact models. In the past, most dynamic simulation tools used an offline wheel-rail contact element based on look-up tables that are used by the main simulation solver. Nowadays, the use of an online nonlinear three-dimensional wheel-rail contact element is necessary in order to accurately predict the dynamic performance of high speed trains. Recently, the Federal Railroad Administration, Office of Research and Development has sponsored a project to develop a general multibody simulation code that uses an online nonlinear three-dimensional wheel-rail contact element to predict the contact forces between wheel and rail. In this paper, several nonlinear wheel-rail contact formulations are presented, each using the online three-dimensional approach. The methods presented are divided into two contact approaches. In the first Constraint Approach, the wheel is assumed to remain in contact with the rail. In this approach, the normal contact forces are determined by using the technique of Lagrange multipliers. In the second Elastic Approach, wheel/rail separation and penetration are allowed, and the normal contact forces are determined by using Hertz’s Theory. The advantages and disadvantages of each method are presented in this paper. In addition, this paper discusses future developments and improvements for the multibody system code. Some of these improvements are currently being implemented by the University of Illinois at Chicago (UIC). In the accompanying “Part 2” and “Part 3” to this paper, numerical examples are presented in order to demonstrate the results obtained from this research.

Dynamic and Quasi-Static Grade Crossing Collision Tests

To support the development of a proposed rule [1], a full-scale dynamic test and two full-scale quasi-static tests have been performed on the posts of a state-of-the-art (SOA) end frame. These tests were designed to evaluate the dynamic and quasi-static methods for demonstrating energy absorption of the collision and corner posts. The tests focused on the collision and corner posts individually because of their critical positions in protecting the operator and passengers in a collision where only the superstructure, not the underframe, is loaded. There are many examples of collisions where only the superstructure is loaded. For the dynamic test, a 14,000-lb cart impacted a standing cab car at a speed of 18.7 mph. The cart had a rigid striking surface in the shape of a coil mounted on the leading end that concentrated the impact load on the collision post. During the dynamic test the collision post deformed approximately 7.5 inches, and absorbed approximately 137,000 ft-lbs of energy. The SOA collision post was successful in preserving space for the operators and the passengers. For the quasi-static test of the collision post, the collision post was loaded in the same location and with the same fixture as the dynamic test. The post absorbed approximately 110,000 ft-lb of energy in 10 inches of permanent, longitudinal deformation. For the quasi-static test of the corner post, the post was loaded at the same height as the collision post, with the same fixture. The corner post absorbed 136,000 ft-lb of energy in 10 inches of permanent, longitudinal deformation. The series of tests was designed to compare the dynamic and quasi-static methods for measuring collision energy absorption during structural deformation as a measure of crashworthiness. When properly implemented, either a dynamic or quasi-static test can demonstrate the crashworthiness of an end frame.

Improved Tank Car Design Development: Ongoing Studies on Sandwich Structures

The Government and industry have a common interest in improving the safety performance of railroad tank cars carrying hazardous materials. Research is ongoing to develop strategies to maintain the structural integrity of railroad tank cars carrying hazardous materials (hazmat) during collisions. This paper describes engineering studies on improved tank car concepts. The process used to formulate these concepts is based on a traditional mechanical engineering design approach. This approach includes initially defining the desired performance, developing strategies that are effective in meeting this performance, and developing the tactics for implementing the strategies. The tactics are embodied in the concept. The tactics and concept evolve through engineering design studies, until a design satisfying all of the design requirements is developed. Design requirements include service, manufacturing, maintenance, repair, and inspection requirements, as well as crashworthiness performance requirements. One of the concepts under development encases the pressurized commodity-carrying tank in a separate carbody. Moreover, this improved tank car concept treats the pressurized commodity-carrying tank as a protected entity. Welded steel sandwich structures are examined as a means to offer protection of the commodity tank against penetrations from impacting objects in the event of a collision. Sandwich structures can provide greater strength than solid plates of equal weight. Protection of the tank is realized through blunting of the impacting object and absorption of the collision energy. Blunting distributes impact loads over a larger area of the tank. Energy absorption reduces the demands on the commodity tank in the event of an impact. In addition, the exterior carbody structure made from sandwich panels is designed to take all of the in-service loads, removing the commodity tank from the load path during normal operations. Design studies described in this paper focus on the protection aspect of using sandwich structures. Studies are conducted to investigate the influence of different parameters, such as sandwich height and core geometry, on the force-deformation behavior of sandwich structures. Calculations are carried out numerically using nonlinear finite element analysis. These analyses are used to examine the crashworthiness performance of the conceptual design under generalized impact scenarios.

Mechanical Properties of Tank Car Steels Retired From the Fleet

As a consequence of recent accidents involving the release of hazardous materials (hazmat), the structural integrity and crashworthiness of railroad tank cars have come under scrutiny. Particular attention has been given to the older portion of the fleet that was built prior to steel normalization requirements instituted in 1989. This paper describes a laboratory testing program to examine the mechanical properties of steel samples obtained from tank cars that were retired from the fleet. The test program consisted of two parts: (1) material characterization comprised of chemical, tensile and Charpy V-notch (CVN) impact energy and (2) high-rate fracture toughness testing. In total, steel samples from 34 tank cars were received and tested. These 34 tank cars yielded 61 different pre-1989 TC128-B conditions (40 shell and 21 head samples), three tank cars yielded seven different post-1989 TC128-B conditions (four shell and three head samples), and six tank cars yielded other material (A212, A515, and A285 steel) conditions (six shell and five head samples). The vast majority of the TC128-B samples extracted from retired tank cars met current TC128-B material specifications. Elemental composition requirements were satisfied in 97 percent of the population whereas the required tensile properties were satisfied in 82 percent of the population. Interpretation of the high-rate fracture toughness tests required dividing the pre-1989 fleet into quartiles that depended on year of manufacture or age, and testing three tank cars per quartile. Considering the high-rate fracture toughness results at 0°F for the pre-1989 fleet, 100 percent of the oldest two quartiles, 58 percent of the second youngest quartile, and 83 percent of the youngest quartile exhibited adequate or better fracture toughness (defined as toughness greater than 50 ksi√in). High-rate fracture toughness at –50°F was adequate for 83 percent of two quartiles (the youngest and second oldest), but the other two quartiles exhibited lower toughness with only 33 (2nd youngest) to 50 percent (oldest) exhibiting adequate properties.

RF Coupling Simulation Model Development for Optimal Placement of Antennas Supporting Wireless Communications Systems

The locomotive cab’s limited rooftop area requires that the transmitting and receiving antennas for communications be placed in close proximity to one another. Currently, no means exist to aid the railroad radio frequency (RF) engineer in placing these antennas so that mutual communications interference is minimized. The goal of this paper is to describe a method that can be used to determine optimal antenna placement in a time- and cost-effective manner. The method described below utilizes various forms of the Friis transmission equation in Monte Carlo simulations.

A New Security and Safety Solution for Public Guided Transport

Railway and Public Guided Transit Properties often employ large numbers of video cameras to supervise critical areas and facilitate incident management. Capabilities of Central Control Staff is, however, limited to check the increasing number of CCTV images and so far automated image processing solutions had been insufficiently reliable. TelSys GmbH (a railway telematics company in Dresden, Germany) had therefore developed over the last seven years together with the University of Technology in Dresden and some public transport providers (subway of Berlin, subway of Prague) a robust solution to supervise automatically critical areas like tunnel entrances, station tracks or station platform edges. Also qualifications with German Railways and in Finland had been performed. The automatic image processing software reliably differentiates between trains (“permitted” objects) and objects that move from the platform into the tracks or move too close to otherwise prohibited areas. Object sizes, alarm times, reliability and safety requirements had been taken from the VDV 399 standard of the German Public Transport Operators Association. After years of reliability and safety research and demonstration the system is now in regular operation (stopping automatically incoming driverless trains if an object is detected in the track) and can be considered as the first safe video image processing system according to railway standards. Experiences, system architecture and principles as well as further development plans and planned demonstration installation in North America are discussed.