Uneven Track Research Articles

Research on influence of track stiffness on development of rail squat defects

This paper presents research aiming to establish the relationship between track stiffness and the appearance and development of squat defects on running rails. Uneven incidence of squat defects was observed on the rails of the investigated main transit track in arailway station. Inspection of track support conditions was conducted using an electrometric method. The comparative analysis of the research results indicated a correlation between the incidence of squats and the changes in track support stiffness. The electrometric profiles and maps indicate the mixing of material from contaminated track ballast and wet subballast, which leads to uneven track support stiffness. This was determined as the main cause of occurence of squats and track geometry deterioration. It was concluded that uniform track stiffness has to be maintained throughout the entire track service life.

A Typology of National Park Co-management Agreements in the Era of Reconciliation in Canada

Parks Canada, in response to commitments undertaken towards reconciliation, has signaled its readiness to reassess the participation of Indigenous peoples in the co-management of national parks, national park reserves, and national marine conservation areas (NMCAs). However, the effectiveness of co-management, as the established framework underpinning these and other longstanding partnerships between the state and Indigenous groups, has been disputed, based on an uneven track record in meeting the needs, interests, and aspirations of Indigenous communities. This paper explores the potential of co-management to facilitate reconciliation within national parks, reserves and NMCAs by developing a typology of various types of co-management agreements. Addressing a critical knowledge gap in co-management governance, we provide a comprehensive review of 23 negotiated co-management agreements involving the state and Indigenous groups in a national park context. The resulting typology categorizes these agreements according to contextual factors and governance arrangements, offering insights into the feasibility of shared governance approaches with Parks Canada. Moreover, it identifies the strengths and weaknesses of co-management agreements in fulfilling reconciliation commitments. Our findings indicate that, although Parks Canada has implemented innovative approaches to co-management and shown a willingness to support Indigenous-led conservation efforts, true shared governance with Indigenous groups, as defined by international standards, is limited by the Canadian government's evident reluctance to amend the foundational legislation to effectively share authority in national parks.

Non-linear influences of track dynamic irregularities on vertical levelling loss of heavy-haul railway track geometry under cyclic loadings

Abstract With an emphasis on the combined degradation of railway track geometry and components, a new numerical-analytical method is proposed for predicting the track geometrical vertical levelling loss (VLL). In contrast to previous studies, this research unprecedentedly considers the influence of initial track irregularities (ITI) on VLL under cyclic loadings, elastic-plastic behaviour, and different operational dynamic conditions. The non-linear numerical models are simulated using an explicit finite element package known as LS-Dyna, and their results are validated by full-scale experimental and field measurement data. The outcomes are iteratively regressed by an analytical logarithmic function that cumulates permanent settlements, which innovatively extends the effect of ITI on VLL in a long-term behaviour. For a typical heavy-haul railway operating under 30 tons axle load and 60 km/h train velocity, the result indicates that the set of ITI with the highest standard deviation (SD) of vertical profile (VP) degrades faster (37% on average) than that with the lowest SD. Additionally, our new findings reveal that the worst scenario is related to a train running at 60 km/h and carrying a load of 20 tons/axle in an uneven track whose SD of VP evolves from 3.23 mm at N = 0 (ITI) to 7.20 mm, whereas the best one corresponds to a train at 60 km/h and 30 ton axle load in an uneven track whose SD of VP downgrades from 0.48 to 1.50 mm, both at 3 M cycles (or 60 million gross tons). These findings indicate the importance of considering the ITI for predicting track geometrical VLL under cyclic loadings. Therefore, based on this research, an acceptable condition (thresholds) of ITI can be redefined for a minimum effect on VLL, which can support the development of practical maintenance guidelines to extend the railway track service life.

Design of railway transition zones: A novel energy-based criterion

Railway transition zones (RTZs) experience higher rates of degradation compared to open tracks, which leads to increased maintenance costs and reduced availability. Despite existing literature on railway track assessment and maintenance, effective design solutions for RTZs are still limited. Therefore, a robust design criterion is required to develop effective solutions. This paper presents a two-step approach for the formulation of a preliminary-design criterion to delay the onset of processes leading to uneven track geometry in RTZs. Firstly, a systematic analysis of each track component in a RTZ is performed by examining spatial and temporal variations in kinematic responses, stresses and energies using a finite element model of an embankment-bridge transition. Secondly, the study proposes an energy-based criterion to be assessed using a model with linear elastic material behavior and states that an amplification in the total train energy in the proximity of the transition interface is an indicator of increased (and thus non-uniform) degradation in RTZs compared to the open tracks. The correlation between the total strain energy (assessed in the model with linear material behaviour) and the permanent irreversible deformations is demonstrated using a model with non-linear elastoplastic material behavior of the ballast layer. In the end, it is claimed that minimising the magnitude of total strain energy will lead to reduced degradation and a uniform distribution of total strain energy in each trackbed layer along the longitudinal direction of the track will ensure uniformity in the track geometry.

Student-centered instruction can build social-emotional skills and peer relations: Findings from a cluster-randomized trial of technology-supported cooperative learning.

Given the uneven track record of adjunctive social-emotional learning (SEL) programs and waning effects by middle and high school, we propose a more integrative approach to SEL through cooperative learning (CL). CL has demonstrated the ability to improve social-emotional, behavioral, academic, and mental health benefits, but CL lessons are complex and thus can be difficult to design and consistently deliver with fidelity. The present study attempted to address this barrier by examining the effects of technology-assisted CL on five social-emotional competencies, as well as social and behavioral outcomes. Participants were 813 students (50.2% female, N = 408, and 70.7% White, N = 575) from 12 middle and high schools in the Pacific Northwest in a cluster-randomized design where six intervention schools implemented technology-assisted CL and six control schools conducted business as usual. Using multilevel modeling, intervention effects on all outcomes after 1 year were significant, with moderate to large effect sizes, inviting further evaluation of integrative approaches to SEL that are developmentally aligned with the needs of students in secondary education. Although there remains a dearth of universal school-based interventions with demonstrated impacts on social outcomes in middle and high school, the present study builds support for the use of integrative, relationship-based instructional approaches, supported by technology, to promote positive peer relations, and social competencies for this age group. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Application of Odometry and Dijkstra Algorithm as Navigation and Shortest Path Determination System of Warehouse Mobile Robot

One of the technologies in the industrial world that utilizes robots is the delivery of goods in warehouses, especially in the goods distribution process. This is very useful, especially in terms of resource efficiency and reducing human error. The existing system in this process usually uses the line follower concept on the robot's path with a camera sensor to determine the destination location. If the line and destination are not detected by the sensor or camera, the robot's navigation system will experience an error. it can happen if the sensor is dirty or the track is faded. The aim of this research is to develop a robot navigation system for efficient goods delivery in warehouses by integrating odometry and Dijkstra's algorithm for path planning. Holonomic robot is a robot that moves freely without changing direction to produce motion with high mobility. Dijkstra's algorithm is added to the holonomic robot to obtain the fastest trajectory. by calculating the distance of the node that has not been passed from the initial position, if in the calculation the algorithm finds a shorter distance it will be stored as a new route replacing the previously recorded route. the distance traversed by the djikstra algorithm is 780 mm while a distance of 1100 mm obtains the other routes. The time for using the Djikstra method is proven to be 5.3 seconds faster than the track without the Djikstra method with the same speed. Uneven track terrain can result in a shift in the robot's position so that it can affect the travel data. The conclusion is that odometry and Dijkstra's algorithm as a planning system and finding the shortest path are very efficient for warehouse robots to deliver goods than ordinary line followers without Dijkstra, both in terms of distance and travel time.

Dynamic Analysis of a Steel–Concrete Composite Box-Girder Bridge–Train Coupling System Considering Slip, Shear-Lag and Time-Dependent Effects

A dynamic computational program considering slip, shear-lag and time-dependent effects of composite box-girder bridge–train coupling system is firstly proposed based on the authors’ previous studies. In the program, the long-term vertical displacement of a composite bridge is firstly calculated. The calculated vertical displacement is then superimposed on the existing uneven track as the new excitation of the composite box-girder bridge–train coupling system to obtain the dynamic responses of the bridge–train coupling system. A 3 × 40 m simply supported steel–concrete composite box-girder bridge is selected to investigate the influence of its time-dependent behavior on its dynamic responses. The results showed that the time-dependent effect will amplify the dynamic characteristics of the composite box-girder bridge and the high-speed train. The maximum vertical displacement and acceleration of the composite bridge increase by 8.82% and 13.64%, and the maximum vertical acceleration of the train body increases by 144.78%. Additionally, the slip and shear-lag effects have an impact on the dynamic responses of the composite box-girder bridge–train coupling system at different operation times. The dynamic responses of the coupling system strengthen with the decrease in shear connection stiffness. The dynamic responses of the system may be underestimated when the shear-lag effect is not neglected. Therefore, these conclusions should be given sufficient attention in the design, construction and operation of high-speed railway composite bridges.

Analysis on fatigue life of overhead travelling crane girder under impact load for sustainable transport system

As the main bearing structure of the crane, the girder structure determines its service life. While the girder structure meets the strength, stiffness, and stability, its fatigue life should be paid more attention. A strong impact will be caused by the overhead travelling crane running through the uneven track joint. Based on SolidWorks and automated dynamic analysis of mechanical systems, the virtual prototype of 480 t overhead travelling crane operation is established in this study. The operation simulation of various track height differences is carried out. Compared with the theoretical calculation of GB and ISO, the virtual prototype is verified. Through the strain test and finite-element calculation of stress of girder under the two working conditions including the main car with a load of 433 t running to the mid-span and span end of the girder, the stress concentration in the transition rounded corner of the girder is found. On the basis of the simulation load spectrum and finite-element static stress analysis, combined with the S–N curve of material, the fatigue damage and life prediction model of the 480 t overhead travelling crane girder is established. The minimum life of the dangerous part is obtained, providing a basis for the design and maintenance.

Dynamic train-track interactions over railway track stiffness transition zones using baseplate fastening systems

In railway industry, significant attention has been spent to solve stiffness transition zone problems since the railway tracks at these zones, especially at the transition between bridge and embankment, are prone to the significant degradation and they need extra maintenance activities and cost to ensure the safety and comfort of passengers. A variety of applications to solve the transition zone problems have been widely investigated. However, never has the application of baseplate fastening systems to fix the transition zone problem been fully investigated. The study proposed herein is the world’s first investigation to fill the knowledge gap by using numerical models to investigate the effect of baseplate pad stiffness and baseplate weight on the dynamic behaviours of the transition zone between slab track and ballasted track. The numerical models have been simulated using LS-DYNA software and validated by comparing with field measurements and other simulation results. The obtained results present that soft baseplate pads can intensify the rail displacements and increase an uneven track profile at transition zone. The results also show that the effect of baseplate weight play a slight role in reducing the differential settlement. The 400 MN/m/m2 pad stiffness provides the best solution as the slab track stiffness can be equalised to the stiffness of ballasted track. Overall, the optimal stiffness of baseplate can significantly reduce the differential settlement leading to reduce track degradation. However, the uses of heavier baseplates and softer baseplate pads together may cause negative effect by increasing the rail displacements leading to higher differential settlements. Hence, baseplate fastening systems should be carefully selected to maximise the benefit of baseplate fastening systems. The new insights will help track engineers to make an appropriate decision on the design and usage of baseplate fastening systems at the stiffness transition zone to mitigate the risk of accelerated track degradation.

Dynamic response of vehicle–bridge–soil system using lumped-parameter models for structure–soil interaction

Prediction of vibrations generated by railway traffic experiences an increasing interest, as new lines are being constructed and planned in many countries. The paper proposes a numerical model to analyse a coupled vehicle–bridge–soil system, taking into account the most important phenomena affecting the structure, while at the same time being comparatively computationally efficient. Such model is useful in the early design phases of a project, when analysing a range of possible configurations or conducting parametric analysis is required.A simplified vehicle model, nonlinear wheel–rail interaction, a bridge structure modelled using the finite-element method and a semi-analytical model for layered soil are all introduced in the model. A pure time-domain solution procedure is used, utilizing lumped-parameter models (LPMs) for the soil–foundation system. Representation of the dynamic stiffness matrix using LPMs is investigated by analysing the cross-coupling between footings and a novel procedure necessary for computationally stable LPMs is introduced and utilized. Further, pure time-domain solution is compared with an iterative mixed-domain solution. Finally, to illustrate the capabilities of the model, analyses are carried out to determine the resulting maximum and minimum excitation limits resulting from wheel–rail interaction on a number of randomly generated uneven track profiles.

OPTIMIZATION OF MOTION OF AUTOTRANSPORT ON UNEVEN ROADS CONTAINING ASCENDS AND DESCENDS

The impact of roads unevenness, i.e. presence of upward and downward motion zones in the road on auto transport fuel consumption is studied. The task of calculation of optimum interrelation of motion speed and acceleration at the uneven roads in sense of reaching of minimum consumed fuel and minimum emissions on environment is formulated and solved. In the study, an analysis of known works on the topic of research was carried out, which showed that the unevenness of the road, i.e. the presence of descents and ascents on the route is one of the main reasons that led to an increase in fuel consumption by vehicles on the route, while the problem of calculating the optimal functional relationship between the speed and acceleration has not yet been solved. Formulated and solved the problem of finding the optimal relationship between the speed and acceleration of vehicles in terms of achieving the minimum fuel consumption on an uneven track. Practical recommendations have been developed for the implementation of the proposed optimal driving regime on uneven terrain containing descents and ascents.

Improvement of the pointing precision of the Tianma radio telescope with an inclinometer measurement system

To assure high pointing precision of the Tianma radio telescope (TMRT), new models based on a inclinometer measurement system are added to the classical pointing model. This involves four main tasks. Firstly, the inclinometer measurement system is set up and its precision is evaluated. Secondly, a feedback control strategy for pointing error for the turbulences of uneven azimuth track and thermal deformations of alidade is implemented. Thirdly, after removing the linear effect of uneven track, sine fitting inclinometer data obtains the model of nonlinear effect of azimuth-track-level unevenness. The nonlinear effect is less than ±5 arc-sec. The azimuth angles associated with large pointing error show a good agreement with those corresponding to poor track unevenness. Finally, the TMRT inclinometers monitor the effect of thermal deformations of alidade on the pointing precision of elevation from stow position, to observing almost motionless radio source, to arbitrary postures of radio telescope. The measured data after subtracting other affected factors of inclinometer including intrinsic drift, azimuth-track unevenness, variation of the center of gravity have similar tendency with the simulated results of finite element model (FEM). Applying established real-time modified model to observe the radio source 2334 + 8226, the checking results show that the pointing precision improved 65%.

Settlement analysis using a generic ballasted track simulation package

Uneven track settlement inevitably occurs for ballasted track and eventually results in poor track geometry and support stiffness leading to considerably high maintenance cost. Considerable in situ and laboratory experiments have been carried out and empirical formulas have been proposed in order to predict track settlement. Nevertheless, laboratory tests are usually restricted in size for financial reasons and the site characteristics vary significantly to fully understand influential parameters. Therefore, the main aim of the present work is to develop an efficient model capable of replicating localised track settlement for different circumstances. A generic ballasted track simulation package BaTrack is introduced combining the Finite Element (FE) software Abaqus, Python, and Fortran. The three-dimensional (3D) FE model includes rail, sleepers, rail-pads, under sleeper pads (USPs), ballast and foundation layers. An advanced non-linear ballast material model is introduced using porous material properties and extended Drucker-Prager model with hardening and is able to account for different confining pressure values. The model is firstly used for comparison against a series of monotonic triaxial tests and has shown good agreement. It is then validated against a series of full size tests carried out at the Southampton Railway Testing Facility (SRTF). A number of settlement analyses are carried out and characteristics of the stress, contact pressure distribution and void evolution from different track configurations are discussed in detail.

Frost heave analysis of ballasted track above box culvert and its influence on train vibration

The uneven frost heave of frost-susceptible subgrade soil causes track irregularity, which highly enhances train vibration and affects the comfort and safety of railway transportation. This paper presents a coupled thermo-hydro-mechanical (THM) analysis for the freezing behavior of railway located above a box culvert. The vertical acceleration of the vehicle, an indicator of riding comfort, is predicted through a vehicle dynamic model. The results reveal that the existence of a box culvert changes the subgrade thermal pattern, leading to a deeper frost penetration depth. The frost heave amount above the box culvert is larger than the adjacent section, resulting in uneven track structure upheave and track irregularity. This frost-induced track irregularity highly affects train vibration.

SIMULATING PASSIVE SUSPENSION ON AN UNEVEN TRACK SURFACE

<p>Automobile suspension systems have an important role in a vehicle's functioning, especially with regard to driving safety. In the present paper we exhibit the equations that characterize a passive suspension system. Considering that solving the equations is extremely cumbersome we developed a simulation scheme in MATLAB Simulink. The simulation allows for an analysis of the behavior of the passive suspension system on any uneven track surface whose configuration is ensured by stimulus signals. For the simulation we used the quarter car model. The suspension was chosen as having two degrees of freedom. </p>

Influence of tire inflating pressure at dynamic forces acting on articulated trolleybus

SKODA VÝZKUM s.r.o. cooperated on the development of the NEOPLAN DMA low-floor articulated trolleybus intended for the Boston city. Multibody models and finite element models of the trolleybus were utilized in the stage of the vehicle design. At the end of the stage of computer modelling and testing of the trolleybus prototype a decision to reduce tire inflating of vehicles in serial production (together with the change the type of shock absorbers used in trolleybus suspension) was made. The impact of this change on forces acting in the trolleybus suspension elements (i.e. in air springs and shock absorbers) and radius rods on the trolleybus chassis when running on an uneven test track was investigated using multibody simulations. Time histories of the forces calculated utilising multibody models were used as input data of the trolleybus finite element models.

Alternating traction current dynamics in track lines of double-track hauls

The operational stability of track circuits and continuous cab signaling in electrified railway sections is disturbed most often by traction current noises in the track line. They are generated when asymmetrical traction current is produced at the points where track circuit equipment is connected to the tracks or under sending cab coils of continuous cab signaling. From the standpoint of traction current flows, a single-track haul track line can be considered a solitary double-wire circuit with two reciprocally induced singlewire electric circuits. As a result, traction current asymmetry becomes easier to calculate. In the case of double-track hauls, this problem is much more difficult to solve, because the traction network in these hauls additionally includes electrified trackways of adjacent tracks, second contact wire, and longitudinal power supply lines laid on catenary supports. These lines are reciprocally inductive with the considered trackways. The considered hauls are characterized by different distances from each trackway to additional electric lines, for which reason the reciprocal inductances inversely related to these distances are different as well. According to the analysis of the proposed procedure of calculating the traction current asymmetry in the track line, this asymmetry depends not only on electric resistances and specific reciprocal inductances of interlinked singlewire electric power lines, but also on the ratio of currents in these lines. It has been established that the absolute value of traction current asymmetry at a particular point of the track lines is indicated more adequately by the level of impact of traction current asymmetry on the operational stability of track circuits than by the traction current asymmetry factor. The time course of the traction current asymmetry in the track line depends on variations in the ambient temperature, traction current in the rails, and electric resistances in the junctions of parts of track bonds, choke jumpers, and ground circuits of catenary line supports. Additional changes in the traction current asymmetry under sending cab coils occur during train traffic and depend on the inbound resistances of track line sections ahead, as well as on any uneven longitudinal track magnetization.

The European Court of Human Rights’ Uneven Track Record in Engaging with Super-Diversity: in Need of an Overarching Frame of Reference?

Paper presented at IRiS conference University of Birmingham, organised by the Institute for Research into Superdiversity (IRiS) on: ‘Superdiversity: Theory, Method and Practice in an Era of Change’ (23-25 June 2014).

Stoicism, Feminism and Autonomy

The ancient Stoics had an uneven track record with regard to women’s standing. On the one hand, they recognized women as fully capable of rationality and virtue. On the other hand, they continued to hold that women’s roles were in the home. These views are consistent, given Stoic value theory, but are unacceptable on liberal feminist grounds. Stoic value theory, given different emphasis on the ethical role of choice, is shown to be capable of satisfying the liberal feminist requirement that autonomy must be respected. In turn, a model for Stoic feminism is proposed.

Beyond Clear-Hold-Build: Rethinking Local-Level Counterinsurgency after Afghanistan

Despite a highly uneven track record, clear-hold-build has remained a dominant, even universal, approach to counterinsurgency. Its prevalence is rooted in its incontestable sequencing of operations and the attendant promise of a linear path towards peace. Yet the appeal of this approach also makes it deceptive and possibly dangerous. Clear-hold-build is not a strategy and must not be mistaken for one, as it has been in Afghanistan, where it inspired false hope for swift progress. Instead, it is necessary to reach a more problematized view of this approach and of what it aims to achieve. This article provides such an evaluation, proposing five principles that should guide its future application. These principles point to the need for a far deeper understanding of how security, development, and governance interact at the local level. Counterinsurgents must understand the relationships between aid and security, between government and governance, and between state and periphery. Where the central government is predatory or lacks support, clear-hold-build also raises difficult questions of authority, legitimacy, and control – questions that counterinsurgents must be capable of answering. Thus problematized, clear-hold-build emerges as a framework with heuristic utility; a schema that can be helpful in planning but which must at the time of application be populated by knowledge, substance, and skill. The implications of these requirements are troubling, particularly for those governments still in the business of armed intervention.