An improved understanding of the vertical load path is necessary for improving the design methodology for concrete crossties and fastening systems. This study focuses on how the stiffness, geometry, and interface characteristics of system components affect the flow of forces in the vertical direction. An extensive field test program was undertaken to measure various forces, strains, displacements and rail seat pressures. A Track Loading Vehicle (TLV) was used to apply well-calibrated static loads. The TLV at slow speeds and moving freight and passenger consists at higher speeds were used to apply dynamic loads. Part of the analysis includes comparison of the static loads and the observed dynamic loads as a result of the trains passing over the test section at different speeds. This comparison helps define a dynamic loading factor that is needed for guiding design of the system. This study also focuses on understanding how the stiffness of the components in the system affects the flow of forces in the vertical direction. The study identifies that the stiffness of the support (ballast) underneath the crossties is crucial in determining the flow of forces. The advances made by this study provide insight into the loading demands on each component in the system, and will lead to improvements in design.

A target-oriented method for the design of railway wheel profiles is presented. The target chosen is the rolling radii difference function which plays an important role in the dynamics of railway vehicles especially for high speed performances. A computer program based on this method has also been developed and is validated by way of examples in which wheel profiles LMA, S1002G and XP55 are investigated.

The Railroad Industry experiences multiple failures with currently used bonded insulated joint designs. These failures have encouraged an increased effort in strength and fatigue analysis for the joints. This paper presents a program initiated by Virginia Tech and Transportation Technology Center Incorporated (TTCI) to develop, analyze, and test a family of insulated joint designs featuring non-adhesive bolted connections. This program utilizes a hierarchical set of Finite Element (FE) parametric models that explore the problem’s mechanics for a family of rail joint design concepts by refining the analysis with each subsequent model. Currently, there is limited information concerning design criteria for insulated joints in the Railroad industry. Therefore, an initial task in this program is to define design criteria and representative load cases characteristic of typical life cycles for commercial freight rails. Design criteria are either proprietary to the railroad or do not appear to be published in the AREMA handbooks. However, the AREMA handbooks do define an acceptance test for the failure of rail joint. Failure criteria were derived from the AREMA rolling wheel acceptance test with some modifications to the magnitude of the loads. Using these load cases and design criteria, multiple FE models are used to identify the dominant mechanics of the bolted joint and contact problem. Each model features parametric relationships that enable rapid design changes including geometric features and mechanics. The development of hierarchical FE models facilitates the selection of a specific model that embodies the essential mechanics of the problem while maintaining a geometry that allows for parametric tradeoff studies. The design variables and baseline finite element model are used as an analysis tool developed as an Abaqus scripted template for design comparison studies. The hierarchical approach to finite element modeling with a parametric model has been applied to the development of a bolted insulated rail joint design, which has been realized in a new insulated joint prototype. The mechanics explored in the FE models can be verified using various full-scale load frame tests in a controlled environment. Tests are standardized across models using identical boundary conditions and load cases. The results obtained will be used to confirm modeling assumptions and provide necessary information for further prototype development. The prototype of the full 3-D geometry will be tested in track at TTCI for final design verification. The hierarchical parametric finite element modeling approach results in a tool that can be applied to joint design across the rail industry.

The Taiwan High Speed Rail (HSR) line, running north ∼ south, is located at the western corridor of the island with a total length of 345 km., out of which 252 km. are continuous viaducts or bridges. This type of structure was chosen to eliminate on grade crossing for trains travelling at speed of 300 km/hr., this will also allow better land usage on either side of the line. Taiwan is a major earthquake zone, the imperative challenge for the planning and design of this world’s longest HSR viaducts is to provide controlled dynamic responses to the structure for operational safety and passenger comfort. To achieve this goal, dynamic interactions between the running high speed trains and the viaducts need to be studied comprehensively and in details. The result is a specification very different from traditional railway viaduct. SINOTECH Engineering Consultant, Ltd. was involved with this HSR project in various stages including planning for part of the alignment during project development by government agencies, and also basic and detail design of viaducts for the BOT concessionaire THSRC. In this paper an introduction is given on how the major contents of viaduct specific design specification of UIC, Eurocode, Japanese code and Taiwan local code have been combined. How Sinotech approached this challenge, the design method chosen, and a summary of bridge design related to seismic safety and passenger comfort are also described herewith. Finally, the experience gained from Taiwan HSR and suggestions for future HSR design and construction are summarized for the reference of similar projects in the future.

Track substructure design is an often overlooked step in the design of railroad track. The lack of consideration for the substructure when designing track results in greater maintenance demands due to inadequate track substructure performance. Railway track is a stable structure with a progressive failure process that allows track engineers to manage the degradation of the track through maintenance. However, increasing demands for track availability from high traffic volumes require that track maintenance be minimized while ensuring safety. Additionally, developing high speed rail and intercity passenger rail on existing corridors necessitates higher levels of substructure performance due to tighter track roughness tolerances. Reduction in maintenance needs can be achieved by ensuring that new construction and rehabilitation projects be designed to provide a stable track structure throughout the design life. Lack of readily available data for substructure materials is a drawback to the use of track design methods. This paper provides a summary of several available substructure track design methods along with the required data for design. The track design data is related to track measurements that could be used to determine much of the information necessary for design of track rehabilitation. Track load-deflection data could be used to develop much of the needed design data while ground penetrating radar could support delineation of similar track segments. Benefits of track structure design include knowledge of expected life, reduced maintenance, material properties for quality control, and development of material properties that could permit application of performance based contract specifications.

Implementing safety systems on railroads and transit systems to prevent collisions and the risks of excess speeds often come at the price of lengthened trip time, reduced capacity, or both. This paper will recommend a method for designing Positive Train Control (PTC) systems to avoid the degradation of operating speeds, trip times and line capacities which is a frequent by product of train-control systems. One of the more significant operational impacts of PTC is expected to be similar to the impacts of enforcing civil speed restrictions by cab signaling, which is that the safe-braking rate used for signal-system design and which is expected to be used for PTC is significantly more conservative than the service brake rate of the train equipment and the deceleration rate used by train operators. This means that the enforced braking and speed reduction for any given curve speed restriction is initiated sooner than it otherwise would be by a human train operator, resulting in trains beginning to slow and/or reaching the target speed well in advance of where they would absent enforcement. This results in increased trip time, which can decrease track capacity. Another impact of speed enforcement is that it often results in “underspeeding.” In a cab-signal (and manual-train-operation) environment, it has been well documented that train operators typically operate two or three mph below the nominal enforced speed to avoid the risk of penalty brake applications. Target and location speed enforcement under PTC is likely to foster the same behaviors unless the design is prepared to mitigate this phenomenon. While the trip-time and capacity impacts of earlier braking and train-operator underspeeding are generally marginal, that margin can be very significant in terms of incremental capacity and/or resource for recovery from minor perturbations (aka system reliability). The operational and design methodology that is discussed in this paper involves the use of a higher unbalance (cant deficiency) for calculating the safety speed of each curve that is to be enforced by PTC, while retaining the existing maximum unbalance standard and existing speed limits as “timetable speed restrictions”. Train operators will continue to be held responsible for observing the timetable speed limits, while the PTC system would stand ready to enforce the higher safety speeds and unbalance should the train operator fail to properly control his or her train. The paper will present a potential methodology for calculating safety speeds that are in excess of the normal operating speeds. The paper will also calculate using TPC software the trip-time tradeoffs for using or not using this potential concept, for which there are some significant precedents. Other operational impacts, and proposed remedies, will be discussed as well. These will include the issues of total speed enforcement versus safety-speed enforcement, the ability of a railroad’s management to perform the speed checks required by the FRA regulations under normal conditions, and the operation of trains under occasional but expected PTC failures.

Hot Mix Asphalt (HMA) pavements can be used to improve the performance of crossing diamonds and other high dynamic load track segments. HMA underlayments are one method of strengthening track foundations to improve track superstructure performance. Railroads are looking for standardized designs for HMA similar to what is available for ballast section, crossties and rail. Therefore the authors have developed a rational design method and recommended designs for Hot Mix Asphalt (HMA) underlayments at crossing diamonds. A parametric analysis of typical subgrade conditions and mainline railroad loadings was conducted. These results have been compiled into an easy to use table of minimum HMA thickness vs. subgrade strength.

This paper will present the development of composite coil springs made from glass-fiber-epoxy materials. It will also review the results from prototype springs that have been manufactured and tested. Sardou S.A. has been developing and manufacturing composite structures and components of various designs for over 27 years. This experience, especially with composite torsion springs, has led to development, prototype production, and testing of several designs of composite coil springs. The design takes advantage of commercially available glass fiber and epoxy materials. The development process led to proprietary design methods and computer models to simulate unique configurations and material characteristics. The development process also allows design of composite springs for the same or smaller design volume as steel coil springs with comparable spring characteristics. The manufacturing methods that are used apply existing lost mold and winding processes in unique ways to produce prototype composite coils springs. These methods were also developed considering scaling-up and automation for volume production. Several generations of prototype composite coil springs have been produced and tested. Each generation has advanced the design and manufacturing methods. Several features of composite coil springs including light weight, dynamic response, flexibility of design, and fatigue resistance have been demonstrated through testing. Depending the steel counterpart considered, composite coils springs offer weight saving of about 75%, fatigue life improvement, no rust, no creep, and no notch sensitivity at a cost close to that of a steel spring.