High-speed trains, though prevalent in Europe and Asia, are not yet a reality in the US. But interest and industry engagement are growing, especially around commercial hubs close to commuter homes for alleviating commute times. With support from the Federal Railroad Administration in the United States, the authors are exploring the design requirements, challenges, and technology capabilities for wireless communication between passenger cars, on-board systems and with trackside infrastructure, all using next-generation radio access technologies. Key aspects of this work focus on interoperability, modularity of the architecture to facilitate a future-proof design, high-performance operations for passenger services and ultra-low latency capabilities for train control operations. This paper presents the theoretical studies and computer simulations of the proposed network architectures, as well as the results of an LTE/5G field test framework using an OpenAir-Interface (OAI)-based software-defined radio (SDR) approach. Through various test scenarios the OAI LTE/5G implementation is first evaluated in a lab environment and through field tests. These tests provide ground-truth data that can be leveraged to refine the computer simulation model for evaluating large-scale environments with high fidelity and high accuracy. Of particular focus in this evaluation are performance aspects related to delay, handover, bit error rate, frequency offset and achievable uplink/downlink throughput.

The modern society’s continuous increasing mobility requirements have encouraged new transportation technological platforms. The so called Hyperloop concept, also described as the fifth mode of transport (rather than road, rail, water and air) for both passenger and/or freight) is supported on the idea of a pod like vehicle, running in a near vacuum environment (inside tubes) at near sonic speeds, higher than current air transport ones. This technological approach has played a prominent role in the modern transport scenario, with a potential to offer high service levels, associated with high speed, reliability and weather operational flexibility, as well as reduced environmental footprint and costs. This groundbreaking technological concept, albeit revolutionary, can not be seen as a novelty, with previous precursors being proposed in the last century. However, the concept has been reintroduced in 2012 with updated technologies, in an open sourced format, by the acknowledged entrepreneur Elon Musk, to instigate further improvement/development among interested companies worldwide, focused on its exploration on a commercial scale in the near future. The Hyperloop concept is envisioned to compete with both the High Speed Rail (HSR) and Maglev services, in the 160–640 km (100–400 mi) range, as well as air transport, for up to 1,000 km (625 mi) range, with alleged both environmental and cost advantages over their competitors. However, despite the technology’s high performance potential, given its multidisciplinary feature (sonic/high speed, near vacuum, linear motor propulsion, electric power storage, pod environment maintenance/cooling, air quality control, transport capacity, among others) and its inherent current low maturity from both the engineering, operational and cost perspectives, there are several major technological, regulatory, planning, financial and environmental challenges to be addressed, prior to reach the commercial service status. In this context, it is currently required a huge research effort to figure out technological barriers, followed by prototype tests, to set up the safety and operational requirements. Work is current under way, with a huge research effort (from both the academy and the industry) focused on basic technological concepts, as well as some prototype tests (currently unmanned) driven to test the specific main technological approaches in a real world condition. Given its revolutionary feature, Hyperloop technology is seemed as both ambitious and controversial by the general public and transport experts, with some optimistic bets in its medium term revolutionary role in the passenger transport market, focused on some niche segments currently serviced by the rail mode, as well as other skeptical bets in its restricted role to the freight market, given some inherent safety issues. This work is supposed to present a review (supported on the current available technical literature) of the groundbreaking Hyperloop technology concept and its potential to fill some specific rail niche markets, in both passenger and/or freight segments, with an assessment of the main technology’s hurdles/bottlenecks status and their perspectives, from a technological, environmental and cost focus, followed by a snapshot of some potential Hyperloop project candidates.

In this paper, the vertical carbody dynamics of the railway vehicle excited by random track inputs are investigated. The multi-objective ℋ ∞ controllers for carbody weight of the actual, heavy and a mass confined in a polytopic range have been designed with the aim of reducing the wheel forces, heave, pitch and roll body accelerations of the vehicle. Later, the carbody mass is modelled as a free-free Euler Bernoulli beam and the low frequency flexural vibrations of the train body are examined. An omnibus ℋ ∞ controller is synthesized to suppress both the rigid and low frequencies flexible modes of the railway vehicle. The performances of the ℋ ∞ controllers are verified by using the passive and active suspension responses on the right and left rail track disturbances that are represented by the power spectral density functions authenticated for the stochastic real track data collected from the Qinhuangdao-Shenyang passenger railway line in China. Simulation results showed that all controllers exhibit a very good performance by effectively reducing the car-body accelerations in vicinity of the resonanat frequencies while keeping the wheel-rail forces in the allowable limit.

It is well-known that the geometrical characteristics of the indents on prestressing wire used in the manufacture of prestressed concrete railroad ties affect the magnitude of the transfer length. In particular, it has been shown that such parameters as indent depth, indent volume and indent sidewall angle all affect transfer length, with indent volume being a major influence. Previous research has shown that the larger the indent volume, the shorter the transfer length. For full load bearing capacity, it is important that the transfer length not exceed the distance to the rail seat. Consequently, transfer length has been identified as a key diagnostic parameter for evaluating the load bearing capability of prestressed concrete railroad crossties. Furthermore, it has been proposed for use as a valuable quality control parameter. Ongoing research, as well as previously published research results, also indicates that the geometry of the prestressing wire indents plays a major role in the formation of cracking. This is particularly important in the manufacture of concrete ties intended for high speed rail applications. Cracking and debonding of prestressing wires associated with ties in service can result in severe splitting and complete tie failure. It is therefore not sufficient to guarantee a safe transfer length alone, without consideration of the cracking propensity. The wire specifications in standard ASTM A881 are intended to promote quality prestressed railroad tie behavior; however, the detailed causes of cracking and splitting, and the specific indent features that are responsible, are not well-known from a quantitative perspective. Until recently, inspection of prestressing wire indent properties consisted of sampling a few indents from a small segment of wire, providing very limited statistical information on wire indent properties. To address this deficiency, a high-resolution automated non-contact optical wire indent scanning system has been developed for completely and rapidly characterizing all relevant indent geometrical parameters. The system is capable of measuring large segments of wire to yield statistically significant samples of all relevant indent parameters including indent depth, indent width, indent sidewall angle, indent pitch, and indent volume. The current state-of-the-art in this system development, along with some new insights based on recent indent scanning results, will be presented. This system represents a valuable tool to aid in identifying the key indent geometrical features related to cracking. The overall goal is to quickly assess critical indent parameters, so as to ensure high-quality bond and eliminate in-track tie splitting failures.

As an important element in track, pre-stressed concrete railroad ties in the high-speed rail industry must meet the safety and performance specifications of high-speed trains. Systematic destructive and non-destructive evaluation of existing concrete ties can lead to a better understanding of the effect of prestressed concrete tie material design on performance and failure within their service life. It has been evident that environmental and climate conditions also have a significant impact on concrete railroad ties, causing various forms of deterioration such as abrasion and freeze-thaw damage. Understanding of the material characteristics that cause failure in different types of existing concrete railroad ties taken from different places is the main focus of this paper. Observing the current status and damages of railroad ties taken from track might give a correlation between the material characteristic and type of distress and cracking seen. Although it has been seen by previous works that effective factors such as air void system and material composition directly affect the performance of concrete ties such as freeze-thaw, material evaluation of existing ties after service life has not been addressed in previous publications. In this research, the authors have investigated the material characteristic such as aggregate and air-void system of existing pre-stressed concrete railroad ties taken from track. However, compressive and splitting tensile strength and fractured surface of samples cored from the ties were acquired. In order to obtain the strength of concrete materials of existing ties, six samples were cored from six different types of ties taken from tracks across the U.S., according to ASTM C42-16, and tested using ASTM C39 and ASTM C496 methods. However, the concrete air-void system (ASTM C457) was measured on saw-cut samples extracted from the ties to evaluate the influence air content and distribution on mechanical properties of the ties. Regarding the history and service life condition of the ties, it seems that material properties of the ties effectively alter the performance of the ties. Aggregate sources used at each location may have different properties such as texture, angularity, and mineralogy, contributing either propagation or resistance in splitting cracking in concrete. Furthermore, the polished surface of samples extracted from the ties show the uniformity and air void system in some ties which demonstrate their superiority in terms of resistance to freeze-thaw damage. Considering the results of this research, comprehensive evaluation of material characteristics might give a better view of existing concrete railroad ties situation, providing a worthwhile background for future tie design considerations.

The increasing movement of people and products caused by modern economic dynamics has burdened transportation systems. Both industrialized and developing countries have faced transportation problems in urbanized regions and in their major intercity corridors. Regional and highway congestion have become a chronic problem, causing longer travel times, economic inefficiencies, deterioration of the environment and quality of life. Congestion problems are also occurring at airports and air corridors, with similar negative effects. In the medium distance travel market (from 160 up to 800 km), too far to drive and too short to fly, High Speed Rail (HSR) technology has emerged as a modern transportation system, as it is the most efficient means for transporting large passenger volumes with high speed, reliability, safety, passenger comfort and environmental performance. HSR system’s feasibility will depend on its capacity to generate social benefits (i.e. increased mobility rates, reduced congestion, capacity increase and reduced environmental costs), to be balanced with the high construction, maintenance and operational costs. So, it is essential to select HSR corridors with strong passenger demands to maximize these benefits. The first HSR line was Japan’s Shinkansen service, a dedicated HSR system, between Tokyo and Osaka, launched in 1964, which is currently the most heavily loaded HSR corridor in the world. France took the next step, launching the Train à Grande Vitesse (TGV), in 1981, with a dedicated line with shared-use segments in urban areas, running between Paris and Lyon. Germany joined the venture in the early 1990 with the Inter City Express – ICE, with a coordinated program of improvements in existent rail infrastructure and Spain, in 1992, with the Alta Velocidad Espanola – AVE, with dedicated greenfield lines. Since then, these systems have continuously expanded their network. Currently, many countries are evaluating the construction of new HSR lines, with European Commission deeming the expansion of the Trans European Network as a priority. United Kingdom, for example, has just awarded construction contracts for building the so called HS2, an HSRexpanded line linking London to the northern territory. China, with its dynamic economic development, has launched its HSR network in 2007 and has sped up working on its expansion, and currently holds the highest HSR network. United States, which currently operates high speed trainsets into an operationally restricted corridor (the so called Northeast Corridor (NEC), linking Washington, New York and Boston), has also embarked into the high speed rail world with the launch of Californian HSR Project, currently under construction, aimed to link Los Angeles to San Francisco mega regions, the ongoing studies for Texas HSR project, to connect Dallas to Houston, into a wholly privately funding model, as well as studies for a medium to long term NEC upgrade for HSR. Australia and Brazil are also seeking to design and launch their first HSR service, into a time consuming process, in which a deep discussion about social feasibility and affordability is under way. This work is supposed to present an overview of HSR technology worldwide, with an assessment of the main technical, operational and economical features of Asian and European HSR systems, followed by a snapshot of the general guidelines applied to some planned HSR projects, highlighting their demand attraction potential, estimated costs, as well as their projected economic and environmental benefits.

This paper provides a review of me of the main themes in North American R&D and technology innovation from the 1970s through 2017. A chronological description identifies some of the principal developments in safety and performance over the years, including the introduction of new technologies, the changes in government and industry priorities and funding for R&D. This includes investments in tank car/hazmat research, maglev, and high speed rail). Key technology introductions such as automated track and rolling stock inspection systems are discussed. The evolving and changing roles of the Federal government, the AAR, individual railroads, the supply industry are described. The paper offers a timeline of key events in railroad R&D and technology introductions, with brief discussions each came to pass, the conditions in the industry which drove or enabled them and the impacts each introduction have had. The paper closes with some thoughts about current trends in technology and railroad R&D and their likely trajectory into the future.

Safety is a top priority for the development of worldwide high-speed rail systems. Ballast flying is a particular safety concern when a high-speed train is traveling above a certain speed on the ballasted track. Displaced ballast particles from the track may cause damages to rolling stock, as well as the track infrastructure and wayside structures close to the sides of way. The objective of this research is to develop a probabilistic modeling framework to estimate the probability of ballast flight on specific segments or routes, accounting for several principal risk factors. Based on the probabilistic assessment, we propose a methodology to quantify the probability of flying ballast under certain scenarios. The methodology can be further developed, ultimately enabling a normative risk assessment for flying ballast risk management.

Advanced active suspension systems has attracted considerable attention in modern railway vehicle designs in recent years. The purpose of the suspension is to attenuate the vehicle vibrations due to various rail excitations. With active suspensions it is aimed to improve the performance in some cases, while not making it worse in others. The performance-related objectives can be approximately translated in different norm bounds on certain transfer functions or impulse responses. In this paper, a multi-objective problem is formulated as a non-convex and non-smooth optimization problem for a full-car railway vehicle modelled with seventeen-degrees-of-freedom (17 DOF) and excited by random rail inputs. The controller order restricted to be less than or equal to the passive system model order. For a range of orders, controllers are synthesized by using the HIFOO toolbox.

With the development of high-speed rail technology, the interaction between wheel and track becomes more serious, which threatens the running stability, riding quality and safety of the vehicle. Due to the selected stiffness and damping parameters, conventional passive suspensions cannot fit in with the diverse conditions of the railway. Additionally, among these vibrations contains a large amount of energy, if this vibrational energy can be recycled and used for the active suspension to control, it will be a good solution compared to the conventional passive suspensions. Many energy-harvesting shock absorbers have been proposed in recent years, the most popular design is the electromagnetic harvester including linear electromagnetic shock absorbers, rotational electromagnetic shock absorbers, the mechanical motion rectifier (MMR), and the hydraulic electromagnetic energy-regenerative shock absorber (HESA). With different energy converting mechanisms, the complicated effects of the inertia and nonlinear damping behaviors will severely impact the vehicle dynamic performance such as the ride comfort and road handling. In the past few years, engineers and researchers have done relevant researches on HESA which have shown that it has good effects and proposed several suspension energy regeneration solutions for applying to car. This paper presents a novel application of HESA into a bogie system for railway vehicles comparing to the conventional suspension systems. HESA is composed of hydraulic cylinder, check valves, accumulators, hydraulic motor, generator, pipelines and so on. In HESA, the high-pressure oil which is produced by shock absorber reciprocation could be exported to drive the hydraulic motor, so as to drive the generator to generate electricity. In this way, HESA regenerate the mechanical vibrational energy that is otherwise dissipated by the traditional shock absorber as heat energy. Because the bogie has two sets of suspension systems, a dynamic model of bogie based on AMESim is established in order to clarify the influence of the dynamic characteristics effect and the energy harvesting efficiency when installing the HESA into different sets of the bogie. Then, set the HESA model into each suspension system of the bogie and input with the corresponding characteristic excitation, the influence of the dynamic characteristics and the energy harvesting efficiency are analyzed and compared. The simulation results show that the system can effectively reduce the vibration of the carriage, while maintaining good potential to recycle vibratory energy. Based on the results of the simulation, the relationships as well as differences between the first suspension system and second suspension system have been concluded, which are useful for the design of HESA-Bogie. Moreover, comparing the energy harvesting efficiency discrepancy between the two suspension systems, the potential of energy harvesting of a novel railway vehicle bogie system with HESA has been evaluated and then the best application department has been found, which indicates the theoretical feasibilities of the HESA-bogie to improve the fuel economy.

The support structure beneath railroad tracks may appear to be a simple layering of various materials, but rather, it is a complex system working together to distribute the load of passing trains. It is paramount that this structure maintain its designed support properties not only to preserve component life expectancy but to maintain the safety of the trains traveling over the rails. During normal operations, track geometry, as evaluated through the standard deviation of various track geometry channels, tends to degrade over time. This is a byproduct of the cyclical loading applied to the track structure by passing trains causing the slow compacting and settling of the ballast and sub-structure. Assuming all variables are held constant, a regular maintenance schedule should bring track geometry back into acceptable limits, but this is generally not the case in real life. In the event that the subgrade cannot support and distribute the pressure caused from the passing train successfully, accelerated track geometry degradation can take place. This accelerated degradation can be further increased when there exists a transition between support strengths which can lead to increased dynamic loading. A case study in sub-structure pressure management has been devised and applied to a high speed rail line. During a recent track renewal operation where track was maintained down to the subgrade, pressure transducers were placed within the sub-grade layer under both the left and right rails, inside and outside of track regions where sub-structure management has been applied. This test segment was monitored over a period of one year with both pressure and track geometry data being recorded at regular intervals. This paper will explore the relationship between sub-structure pressure and local track geometry measurements as it relates to the monitored test segment with a region of known subgrade management transition. Numerous numerical techniques will be applied to understand the change over time of the subgrade pressure distribution capability (measured as pressure beneath the rail) and the degradation of various track geometry channels individually over time. Correlation of the pressure data to track geometry data will also be done using both raw data and data processed using numerical techniques. This will lead to an understanding of how the quality of the track support structure, specifically the track support structure’s ability to distribute pressure, can affect the magnitude and degradation rates of various track geometry channels.

Concrete railroad ties have been used in increasing numbers in the U.S., particularly in high-speed rail, heavy-haul freight lines, and new track construction because of their reduced deflections, durability, and competitive cost. In-track assessment of concrete railroad ties can be a challenge, however because many exterior tie surfaces are covered by tie pads and rail or ballast. This damage may include concrete section wear from abrasion, cracking, or crumbling, or other types of defects. Damage internal to the concrete can also not be seen visually. The time and cost needed to inspect these tie surfaces means that it is not routinely performed. Non-destructive testing offers promise as a way to assess concrete tie integrity without having to remove ballast, however more information is needed to know how well non-destructive techniques work in detecting damage. Two of the most promising techniques for investigating the integrity of concrete non-destructively are ultrasonic pulse velocity and impact-echo. Ultrasonic pulse velocity (UPV) and Impact-echo (IE) were applied to investigate the uniformity of concrete railroad tie and its cavities, cracks and defects for concrete ties taken from track after service. This paper evaluated the variability of the test results in UPV and IE testing condition in which two concrete railroad ties with same manufacture and load history condition were tested in both methods. Two additional concrete ties with the same manufacture and load history as each other with visible longitudinal cracks were also examined to see how the damage affected the variability measured. For this purpose, wave pulse for every full length tie from full top, half top, longitude and two sides were measured using ultrasonic pulse (ASTM C597). Also, thickness of concrete ties on both sides, including rail seat location and the middle were assessed by standard tests method for measuring the p-wave speed and the thickness of concrete using the impact-echo method (ASTM C1383). Advice is given on how to interpret ultrasonic pulse velocity and impact-echo measurements and given the variability of the test method how to flag ties for potential deterioration given that most ties in service will not have initial measurements taken before damage for comparison.

Ballastless track slab offers excellent stability and durability and has been well accepted in high-speed railways worldwide. Rails are typically laid on precast concrete slabs that are subjected to dynamic load transferred from the rails. Cracks can be induced by shrinkage and mechanical loading in concrete, which accelerates the degradation and affects the performance of the track slab. As tens of thousands of miles of ballastless track are constructed, effective and efficient maintenance for the concrete slabs has become an issue. In this paper, ultra-high performance concrete (UHPC) is proposed to fabricate ballastless track slab. UHPC is a superior fiber-reinforced, cementitioius mortar, which has greatly-improved mechanical strengths and durability. A recently-developed UHPC is evaluated in terms of the flowability, durability, shrinkage, and mechanical properties. A functionally-graded slab design is proposed with the consideration of initial material cost. The slab is cast with two layers: a layer of conventional concrete at the bottom, and a layer of UHPC on the top. A three-dimensional finite element model is developed for ballastless track slab whose flexural performance is investigated and compared with that of slab made with conventional concrete. Concrete damage plasticity model is incorporated to consider the post-cracking behavior. The results indicate that the proposed UHPC is promising for fabricating ballastless track slab with superior performance.

The interaction between the train, track, and bridge was considered as an interaction between two decoupled subsystems. A first subsystem consisted of the train vehicle simulated as a four-wheelset mass-spring-damper system having two layers of suspensions and ten degrees of freedom. A second subsystem consisted of the track-bridge system assumed to be a top rail beam and a bottom bridge beam coupled by continuous springs and dampers representing the elastic properties of the trackbed smeared over the spacing of the railway ties. The bridge supports were assumed to be rigid or flexible. The equations of motion of a finite element form were derived for each subsystem independently by means of the Newton’s second law. The dynamic interaction between the moving vehicle of the first subsystem and the stationary underlying track-bridge structure of the second subsystem was established by means of a no-separation constraint equation in the contact points between the wheels and the rails. The proposed two-dimensional analysis was intended to accurately describe the vertical behavior of short span bridges subjected to high-frequency excitations due to the passage of high speed trains; therefore, shear deformations, rotational inertia effects, and consistent mass matrices were adopted in the mathematical model. Numerical solutions of the decoupled equations of motion for both subsystems were obtained with the step-by-step direct integration in the time domain using HHT alpha method with a special scheme in the contact interface. The solution accuracy of the proposed method was validated against responses obtained from a semi-analytical method of a train car travelling over a simply supported bridge. The practical engineering application was demonstrated with a case study investigating effects of key parameters in the behavior of a ballasted short span railway bridge. Compared with the moving force model, results showed that for bridges with rigid supports both the vehicle interaction and trackbed produce lower peak responses at resonance speeds with the latter being more significant. However an increase in support flexibility had a greater impact across all speeds in increasing the bridge responses.

The Federal Railroad Administration (FRA) has published a Notice of Proposed Rulemaking (NPRM) that will require passenger rail operators in the United States to develop a System Safety Program using a risk-based hazard management approach. Identified as 49 CFR, Part 270 System Safety Rule [1], the NPRM describes the basic requirements for a system safety program plan, including the need for a method for accepting risk. The NPRM does not, however, identify how the responsible party should actually go about managing risk. That is left up to the railways themselves. In Europe, hazard management is applied in the railroad industry (including high-speed rail systems) under the regulatory authority of the European Union. European Commission Regulation 352/2009/EC [2] outlines a Common Safety Method (CSM) on Risk Evaluation and Assessment for Railways of the European Union, commonly known as the CSM Regulation and the heart of the railway safety program in Europe. The CSM Regulation includes the standard risk assessment process elements: identification of the hazards, corresponding risks, mitigation measures to reduce the risk, and the resulting safety requirements to be fulfilled by the system under assessment. What sets the CSM Regulation apart from other risk assessment programs is that it provides a methodology for determining when acceptable risk is achieved. The risk acceptability of the system under assessment is evaluated using one or more of the following risk acceptance principles: a) The application of relevant codes of practice; b) A comparison with similar systems (reference systems); c) Explicit risk estimation. In essence, the responsible party can accept risk that has either been regulated to an acceptable level by an authority having jurisdiction or a widely-accepted industry practice, or if the risk has been successfully addressed by a similar railway system through that railway’s engineering and operational controls. If neither of these cases applies the responsible party can estimate the risk and choose to accept it or not. A common approach, even internationally, is to develop an explicit risk estimation process based on the U.S. Department of Defense Military Standard 882E (MIL-STD-882E) [3]. Safety hazards are identified, analyzed for risk (severity and probability), and mitigations are progressively applied until a level of safety is achieved that is as low as reasonably practicable. The California High-Speed Rail Authority (CHSRA) has adopted a risk-based hazard management program to achieve an acceptable level of safety for the design, construction, implementation and operation of the California High-Speed Rail System. CHSRA has deliberately used both domestic and international guidance and standards in the development of this program in an effort to apply the most up-to-date processes and philosophies, and to draw upon the impressive safety legacy of international high-speed railway operators. This paper will describe the relevant regulations and guidance (both domestically and internationally), review the elements of a risk acceptance program based upon the CSM Regulation, and apply the program to a select set of hazards to demonstrate how appropriate mitigations can be determined and residual risk accepted. The paper will also identify potential future applications for the CSM Regulation here in the United States, and will challenge the reader to manage hazards using a risk-based approach that incorporates the basic framework of the CSM Regulation.

The rail pad stiffness is one of key design parameters of the track structure, affecting the load distribution along the rail and the dynamic behavior of the track. The rail pad stiffness, however, can be increased under accumulated train load and environmental load, i.e., temperature change, due to the nature of resilient rubber. This study investigates the causes and prediction model of the stiffness increase of the resilient rail pads used in the ballasted and concrete slab track in high-speed railway. For this purpose, in-situ rail pads were taken from several sites, and the static and dynamic stiffness was measured. Also, the repeated load test and accelerated heat aging test on new rail pads in the laboratory have been performed. Based on the test data, proposed is a mathematical model for predicting the increase of the rail pad stiffness according to passing tonnage and elevated temperature.

American railroads are planning to introduce the Positive Train Control System (PTC), a wireless communication system to control passenger and cargo train movements. By design PTC has two networks, the main control network that disseminates trackage rights and a wayside interface unit (WIU) network that beacons track status. One of the main constraints for adopting this system for high-speed trains is the limited bandwidth availability in USA, as higher speeds require more control packets to be communicated using the same radio channel. In this paper we propose an architecture that manages available bandwidth between control and WIU networks by considering the maximum number of trains that has to be simultaneously accommodated by a control point and allocate control channels for the uplink and downlink communication between trains and control points accordingly. The rest of the channels are assigned to wayside devices to minimize interference. Control point locations are decided so that there is proper communication between any train and a control point until the train is handed over to the next control point. The proposed architecture addresses the congestion management, power control and interference avoidance aspects of communication planning for high-speed rail operations. We demonstrate the applicability of our frequency management architecture for a hypothetical train intersection.

Highly efficient energy transmission between Overhead Catenary System (OCS) and pantograph is paramount for high speed railway lines. However this is not usually considered relevant for low speed railway lines. But interruptions in mechanical and electrical contact interfaces increase maintenance costs and can lead to EMI problems with its surrounding environment. In order to avoid this, OCS systems are carefully designed using complex programs for calculation of pantograph/OCS interaction and compared with registered data. This means that it is necessary to invest valuable resources (time and money) to design a proper OCS. At the end of the day, in order to obtain full benefits of a well designed OCS, both careful calculation and installation of all the elements of the system are a must. If no balance between design, calculation and installation is achieved, the overall procedure can present cost ineffectiveness due to wrong or careless installation. The first step of a proper OCS installation process is taking into account all the geometrical and mechanical characteristics and restrictions of the system (maximum and minimum span lengths, slopes, cants, etc.) as well as the relative position of masts, portal structures and head spans to the track. The forces applied by the conductors to each mast and cantilever are established bearing all these data into account. Cantilevers are calculated using these efforts as an input data together with all the geometrical restrictions that the system imposes, thus obtaining their complete geometry and the stresses and strains that they will have to support. These stresses and strains are compared to different standards as well as to rate and calculate masts and foundations. The geometric parameters of the cantilevers are used to prefabricate these elements in order to speed the installation process and to avoid onsite installation errors. A precise calculation process is needed to assure that the contact wire is in the correct position. That’s why a proper calculation tool is needed. CLARA, is a tool developed to perform geometrical and mechanical calculations of OCS cantilevers and rate both masts and masts foundations. This tool has been designed in AECOM Madrid Transportation Design Center by the authors. It is an IT tool that performs this calculation in a precise and quick manner, taking into account all the necessary input data and determining output data to the required level of detail as presented in this paper. This tool provides useful data to design OCS controlling parameters that are of paramount importance for final OCS behavior. Some of these parameters are usually non-controlled due to onsite installation procedures. The authors believe that the use of this tool avoids recalculation, inefficiencies and systematic errors and hence it provides the basis for a more cost efficient design and building process.

Because of its length, the catenary is probably the part of the infrastructure which is the most exposed to lightning strikes: it is a very conductive part, with a significant height, sharp parts and high voltages applied on it. For that reason, different protection schemes are adopted. Surge arresters are installed to limit the over-voltages in the substations, along the catenary and onboard the trains. In addition, an air-termination network (composed of lightning rods or overhead wires, which are grounded) are installed in the substations. The implementation of these schemes normally follows in-house guidelines, established by each infrastructure manager to ensure the compliance with the standards. The physical interpretation of the equivalent area and the expected number of flash strikes is sometimes missing. This paper intends to provide a physical perspective to this problem, using the concept of volume of attraction of each conducting element and linking it to the notion of equivalent area. A specific study case taken for the Madrid-Barcelona 25kV 50Hz high-speed line (Spain) is used to illustrate these concepts.

New and expanded passenger rail projects must deliver dependable scheduled service with affordable operations and maintenance (O&M) costs. Reliability, Availability, and Maintainability (RAM) characteristics of equipment, facilities, and rolling stock determine the dependability and O&M costs of a rail system. System designers, builders, and operators can achieve suitable RAM characteristics by applying established engineering concepts, methods, tools, and techniques throughout the system life-cycle. Targeting and achieving system-wide RAM characteristics are necessary to assure the quality of service delivered to the customers and control O&M costs. A rail project reaps maximum benefits from applying system-wide RAM assurance processes if the RAM activities begin in an early planning phase, whether for a green field or an upgrade project, a single passenger rail system subsystem or a whole new railroad or rail service. Application of RAM assurance processes early on guide design to ensure RAM requirements are met in support of achieving overall service dependability and costs goals. RAM assurance processes are often applied at the railroad subsystem level such as rolling stock, train control, communications, traction power, and even infrastructure and civil works. Key challenges in the early phases of a project are setting the appropriate system-wide performance indicators and metrics, using on-time performance, O&M cost, and other system-wide indicators; and then apportioning those targets to each railroad subsystem in a suitable metric that is measurable and directly relevant to each subsystem and its provider. Once the rail system is integrated and in operation, further steps must assure that the system as a whole meets the system-wide RAM targets. This paper describes a model and associated processes that establish the needed parameter sets, analyses, and metrics, and provides a case study based on a new high-speed rail project.