Rail Integrity Research Articles

Quantitative monitoring of brittle fatigue crack growth in railway steel using acoustic emission

Structural degradation of rails will unavoidably take place with time due to cyclic bending stresses, rolling contact fatigue, impact and environmental degradation. Rail infrastructure managers employ a variety of techniques and equipment to inspect rails. Still tens of rail failures are detected every year on all major rail networks. Inspection of the rail network is normally carried out at night time, when normal traffic has ceased. As the implementation of the 24-h railway moves forward to address the increasing demand for rail transport, conventional inspection processes will become more difficult to implement. Therefore, there is an obvious need to gradually replace outdated inspection methodologies with more efficient remote condition monitoring technology. The remote condition monitoring techniques employed should be able to detect and evaluate defects without causing any reduction in the optimum rail infrastructure availability. Acoustic emission is a passive remote condition monitoring technique which can be employed for the quantitative evaluation of the structural integrity of rails. Acoustic emission sensors can be easily installed on rails in order to monitor the structural degradation rate in real time. Therefore, apart from detecting defects, acoustic emission can be realistically applied to quantify damage. In this study, the authors investigated the performance of acoustic emission in detecting and quantifying damage in rail steel samples subjected to cyclic fatigue loads during experiments carried out under laboratory conditions. Herewith, the key results obtained are presented together with a detailed discussion of the approach employed in filtering noise sources during data acquisition and subsequent signal processing.

Challenges in the Integration of Light Rail and Land Use: A Case Study of Yizhuang Line in Beijing

Transit-oriented development (TOD) is advocated by urban planners as a tool to promote transportation and land use integration, and it has especially been applied in new town developments in Chinese cities. Since 2000, urban metro system construction in Beijing has accelerated and many new towns in suburban areas have emerged due to rail transit connections with the central city. This paper is a case study of Yizhuang new town, which is located in the southeast suburban area of Beijing. It explores whether light rail is successful in promoting transportation and land use integration. First, by comparing the land use within a 1 km radius of three rail stations, findings suggest that the TOD model in terms of land use may not be implemented. Second, by tracing land use changes over time, we found that commercial functions are critical to support TOD development. Third, the mismatch of urban functions between low-skilled labor employment opportunities and high-skilled residential neighborhoods emphasizes the failure of planned reverse commuting patterns. In conclusion, our findings suggest that without a proper land use policy, TOD based on light rail only may not be a successful model in the case of Yizhuang new town. The policy implication is that the planning code of land use should be more flexible and adaptable, in order to promote the integration of transportation and land use in a synergetic way.

Airline and railway disintegration in China: the case of Shanghai Hongqiao Integrated Transport Hub

In China, the need to integrate the air and rail networks has been identified and dozens of transport hubs that include air and HSR links have been built or are planned. In this research, which is complementary to Chen and Lin, the level and potential for air–rail integration at Shanghai Hongqiao Integrated Transport Hub is examined and analyzed. The results show that despite the excellent infrastructure the actual level of integration is low, while the potential benefits from such integration could be very large. It seems that in China the main barrier for air–rail integration is institutional and stems from the institutional (and cultural) division between air and rail transport and from the importance placed on promoting competition almost at any cost – both of these barriers can be said to be ‘imported’ to China from (especially) the U.S. and Europe. But with the infrastructure for air–rail integration in place, the potential to realize such an integration is far greater. A move away from the uni-modal governance and planning of transport can open the door not only to air–rail integration but to the creation of a truly integrated transport system in China.

Integration of Light Rail on the I-90 Floating Bridge across Lake Washington

Installing light rail transit across a floating roadway bridge presents many unique challenges, foremost of which is how to design the multidimensional moving joints at both ends of transition spans between the fixed and floating structures. A technical solution to this technical challenge has been proposed, analyzed, modeled, designed, and prototype tested in the context of the East Link Extension, a light rail transit project being carried out by Central Puget Sound Regional Transit Authority (Sound Transit). Described are the planning, execution, and results of a full-scale prototype testing program of the proposed Curved Element Supported Rail (CESuRa) Track Bridge System, based on the relationship of curved rail supports in two independent planes that adjust in response to the movements of the Interstate 90 (I-90) Bridge. The prototype CESuRa track bridges performed as expected; the information gathered and lessons learned will greatly benefit the final design, the production track-bridge fabrication, and the installation process. Also discussed is the anticipated performance of these track bridges on the I-90 structure in conjunction with the proposed direct fixation track system, fixed rail anchors, and sliding rail expansion joints to be strategically located across the 1.1-mi I-90 Bridge. Built in 1989, the I-90 Bridge is the fifth-longest floating bridge in the world and carries three westbound and two reversible lanes of traffic between Seattle and Mercer Island, Washington. The bridge will be reconfigured to carry four westbound lanes, and the reversible lanes will be converted to light rail transit.

Forecasting passenger travel demand for air and high-speed rail integration service: A case study of Beijing-Guangzhou corridor, China

This paper investigates the mode choice behavior of inter-city passengers among air transport, high-speed rail (HSR), and air and high-speed rail (AH) integration services. Stated preference survey has been conducted for four typical city pairs that are located in the Beijing-Guangzhou corridor, China. Modal split models are proposed and calibrated based on the collected survey data. The proposed models are used to identify the key factors affecting passengers’ mode choices and to estimate the modal split of passenger travel demand for some inter-city transportation markets of China. Sensitivity analyses are also performed to reveal the market potential of the AH integration service in China. It has been found: (i) when the inter-city travel distance exceeds a threshold, passengers become less sensitive to the connection time of the AH service, (ii) the most competitive haul distance for the AH service is between 1200km and 1600km, and (iii) the en route travel time is the most important factor affecting the market share of the AH service.

Analysis of Urban Rail Transit Seamless Transfer Standard

With the improvement of urban rail transit network and traveler requirement of travel , the concept of rail seamless integration has been proposed. This paper analyzes the meaning of integration and seamless integration and the connotation and characteristics of urban rail transport were seamlessly transfer analysis. On this basis, the organization of urban rail transit traffic in different ways are discussed. According to Brighton G (Bou ladon G) hypothesis, tranfer distance is devided into ideal, desirable, acceptable, tolerable, intolerable five levels and their corresponding standard values are quantized, getting the standard of transfer time and distance to evaluate the quality of rail integration and Seamless Transfer of proposeing the standards of integration time and distance.

Non-contact inspection of rail surface and internal defects based on electromagnetic ultrasonic transducers

A non-contact ultrasonic rail integrity inspection technique is discussed in this work as an alternative to concurrent contact-type ultrasonic testing method using piezoelectric transducers, which have some disadvantages due to physical contact between transducers and rails. To this end, transducers which can produce and measure elastic waves in rails without any physical contact were suggested based on electromagnetic ultrasonic transducers. The transducers were designed to selectively produce ultrasonic bulk waves or surface waves according to excitation frequency; it is possible to detect internal and surface defects with same transducer. Simulations using finite element models were performed to determine transducer operating frequencies optimal to defect types. With a series of experiments, it was shown that the proposed method could detect rail internal damages without any physical contact. The effects of air gap between the transducer and a rail and the position of a receiving transducer on the signals were studied to check practical lift-off distance and scanning speed of the method. Non-contact examination of rail surface defects was also carried out using the same transducers only by changing the frequency of excitation current and showed successful results.

Integration of HSR and air transport: Understanding passengers’ preferences

Different solutions for the integration of high-speed rail (HSR) and air transport could be implemented, ranging from very basic integration to more sophisticated systems which include ticket and handling integration. A discrete choice experiment is conducted to better understand passengers’ preferences. We estimate a number of flexible choice models, taking into account the existence of systematic and random taste heterogeneity. We obtain a range of willingness-to-pay values for service quality attributes, finding some important results that can be used to infer policy conclusions about the real attractiveness of the Air–HSR integrated alternative. In this respect, we find that schedule coordination which reduces connecting time will be crucial.

Evaluation Index System of Urban Rail and Bus Transfer Integration

Integration is not only the main content of development of urban passenger transport system, but also the urgent need to raise the level of public transport services and enhance the attractiveness of public transport. Thus coordination of urban rail transit and conventional bus transit systems is an inherent requirement of implementation of public transport priority development strategy. In the context of rapid development of rail transit in domestic cities, after summarizing the theory and practice of integration of urban rail and conventional bus transit, this paper analyzed the meanings and levels as well as the evaluation method of coordination between urban rail system and conventional bus system. On the basis of analysis, the evaluation indexes of coordination between urban rail system and bus system from institutional, technological and economic views are defined. After that, an evaluation index system of integration level of urban rail network and conventional bus network was set up.

Noncontact ultrasonic guided wave inspection of rails

This article describes a new system for high-speed and noncontact rail integrity evaluation being developed at the University of California at San Diego. A prototype using an ultrasonic air-coupled guided wave signal generation and air-coupled signal detection has been tested at the University of California at San Diego Rail Defect Farm. In addition to a real-time statistical analysis algorithm, the prototype uses a specialized filtering approach due to the inherently poor signal-to-noise ratio of the air-coupled ultrasonic measurements in rail steel. The laboratory results indicate that the prototype is able to detect internal rail defects with a high reliability. Extensions of the system are planned to add rail surface characterization to the internal rail defect detection. In addition to the description of the prototype and test results, numerical analyses of ultrasonic guided wave propagation in rails have been performed using a Local Interaction Simulation Approach algorithm and some of these results are shown. The numerical analysis has helped designing various aspects of the prototype for maximizing its sensitivity to defects.

Practices and motivations of travellers making rail–cycle trips

Currently only 2% of British rail passengers choose to cycle to the station, in contrast to 40% in the Netherlands, but the combination of cycling with rail use presents a potentially attractive alternative to car use with carbon reduction and health-promotion benefits. The present study examined the motivations and behaviours of people who integrate bicycle and rail use, focusing particularly on the provision of station cycle parking as a facilitator. A novel methodology was applied to two intercity stations in Bristol (southwest England) to examine movements within an extensive cycle parking area. Bike–rail integration emerges as a complex set of practices, influenced by a range of factors including, but not limited to, the availability of station cycle parking. It is concluded that bike–rail integration can make a contribution to reducing both carbon emissions and car dependence, but a lack of integration within the rail industry and other agencies is limiting the delivery of policies to enhance the opportunities.

Intermodal integration in air transportation: status quo, motives and future developments

Soaring air traffic, increasing urban expansion and airports operating at full capacity are reasons that have caused a discussion about improvements in airport landside access systems. One approach to better match customer demands and address airport congestion is to facilitate the intermodal integration of airports. Building on a survey on intermodal passenger air transportation, we elaborate on the current and future situation at major airports. Our findings indicate a high modal concentration and dependence on individual access modes. However, while airport managers intend to reduce the share of these modes, they plan to increase that of high-occupancy airport access modes. We analyze the underlying motives that cause airports to extend their connections to surface infrastructure. In a case study, we assess an intermodal best practice solution for the integration of air and rail.

Evaluation of slant crack propagation under RCF in railway rail

Crack propagation due to rolling contact fatigue (RCF) could be a significant potential challenge to the integrity of railway rails because it may lead to a serious disaster. Fatigue cracks subjected to cyclic rolling contact force experience a complex non-proportional mixed loading and complicated boundary condition. In the present research, complex crack opening/closure/sliding/locked behaviors as the cyclic contact loading movement is analyzed considering liquid lubrication action on rail surfaces as well as crack faces. Based on a series of FE analyses, the calculations of the effective SIF ranges for RCF cracks under certain contact loading and boundary conditions are proposed in the form of polynomial functions which will be appropriately used to predict RCF crack growth rate.

Integrasi Angkutan Keretaapi Dengan Bus Damri Di Stasiun Tugu Yogyakarta

Yogi;akarta cihj is one of the tourist cihj and a universihj to11m and a cih; full of culture that hard tobreak, other than within the cih;, as well as tourists from abroad and students wlw want to registersclwols that migrate out of population yogi;aknrtn yogyaknrta with routine e7.1en; Idul Fitri, flockflocked to visit nyeknr fogjaknrtn . One of tile 11zo1ks arf' quite populnr and beazme tlze people's choiceis rail, because beside the railwm; is a mode of mass transit modes of transportation also has someadvantages safe, comfortable, safe and timely when compared with other transportation modes.Yogi;aknrta Tugu station to sen1e several hjpes of rail freight business executives and train withpassengers on auerage each dm; to reach 6.5 t/wusand passengers, especially on big dm;s and weeksand, with the number of passengers, the passengers off the train modes require continued until hereached the final destination, especially passengers wlw headed jogja town with a bus transportationmodes, especially road Oamri. One of tlze expected proficienci; le7.1el in these sulusi overcome theMunicipal Government of Yogi;aknrtn (Yogi;aknrtn Transportation AgenCIJ) with PT. Rnilwm;s andPerum Oamri cooperation provided means of road transport continued until he reached the finaldestination of the integration of rail with bus transportation Oamri.

Microstructure Features and Contact Fatigue Crack Growth on Rail

Rolling Contact Fatigue (RCF) damage on the surface of rails such a head check, squats is a growing problem. Since rail fractures can cause derailment with loss of life and property, the understanding of rail fracture mechanism is important for reducing damages on the rail surface. In this study, we have investigated RCF damage, fatigue growth and fracture surface morphology on the surface of broken rail using failure analysis and finite element (FE) analysis. The investigation indicates that the crack grows at about 20° to the depth of 8mm from the surface and branches into two cracks. One crack propagates downward at about 47°, the other propagates upward. Since the crack growth rate of the downward crack was faster than that of upward crack, rail eventually was broken. Since the downward branches lead to fracture of the rail, they are more dangerous to the integrity of rails. It has been observed that White Etching Layer (WEL) occurs within the surface of broken rail. It was found that the fatigue crack initiation and propagation was accelerated by WEL.

Long-term perspectives of intermodal integration at airports

Encouraged by increasing urban expansion and soaring air traffic, connectivity between airports and other modes of transportation has become increasingly important. To mitigate airport congestion and better match customer demands, airport managers are exploring the intermodal integration of airports, particularly through the fostering of concepts such as air–rail integration. This paper studies external influences on intermodality and analyses the motivations of different stakeholders with respect to the integration of their infrastructure. Based on a survey at major airports worldwide, the paper elaborates on the current situation of intermodality at airports in Europe, Asia and the Americas. The results indicate that, even now, many airports still strongly depend on cars as the main access mode. To derive future trends in intermodal integration, the paper analyses potential developments under a changing environment. It thereby develops a framework and offers two polar scenarios. The analysis indicates that the importance of intermodality for the aviation industry is likely to increase, particularly that of air–rail integration, regardless of the chosen scenario.

Transport logistic services in Russia: Integration in the world market

This paper considers problems of increased foreign trade networks requiring faster growth of multimodal shipping and exact coordination of all points in the chain of freight delivery. Special attention is paid to rail and sea shipping integration in major directions of freight flows.

Competition between wear and rolling contact fatigue at the wheel—rail interface: some experimental evidence on rail steel

Recent studies of the rail—wheel interface have shown that wear and rolling contact fatigue (RCF) are competitive phenomena. Wear, by removing the material from the contact surface, tends to limit the propagation of cracks formed by cyclic contact stresses. Several parameters influence these phenomena. This article studies the effects of various working conditions on the surface damage of railway steels. The competition between wear and RCF is particularly strong in dry rolling—sliding contacts, in which the damage severity of our test cases can be adequately predicted using the shakedown map. In wet contacts, RCF is prevalent: cracks rapidly propagate into the subsurface layer in response to hydraulic pressure penetration and then branch towards the surface causing severe damage (macroscopic pitting). The severity of this phenomenon depends strongly on the applied load and cannot be inhibited by wear due to the low friction. On the basis of these results, a general procedure is proposed to the structural integrity of rails.

Service Orientation, Bus–Rail Service Integration, and Transit Performance

Service orientation is one of the most important decisions that a transit manager makes. A manager can concentrate service on the central business district (CBD) or disperse service to connect multiple destinations. Conventional wisdom suggests that transit managers should focus on serving the CBD, because that—such wisdom suggests—is where riders wish to travel. In some places, the service orientation decision is complicated by the need to define the specific role to be played by rail service. Some managers may view rail transit as part of an integrated network structure. Other managers may view it simply as the functional equivalent of a high-capacity bus route. This research examines the relationship between service orientation, bus–rail service integration, and transit performance in U.S. metropolitan areas with between 1 million and 5 million people. Metropolitan areas that have integrated their rail transit into a decentralized network structure are found to enjoy higher riding habit, higher service productivity, and better cost-effectiveness than metropolitan areas with other network structures or modal combinations. These findings suggest the need for transit managers to carefully consider the relationship between service orientation and bus–rail integration to better serve their customers and improve overall transit performance.

Experimental and Numerical Characterization of a Rail Steel Behavior under Cyclic Contact Stresses

Wear and rolling contact fatigue interaction in rolling/sliding contact is an important topic in the research on structural integrity of rails and railway wheels. Wear is in competition with rolling contact fatigue, as it removes surface material layers, reducing cracks length and hindering their propagation. Cracks nucleate by accumulation of cyclic unidirectional plastic strain (ratcheting). In this paper a model for ratcheting assessment is discussed and applied to the UIC 900A steel, after a calibration based on experimental results. The experimental tests allow also a characterization of the crack formation condition for this material. By this model, a computer program is developed in order to simulate in a very short time the effect of a large number of load cycles, providing a tool for predicting crack formation and propagation rates.