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Scrap tyres are a significant source of pollution and pose a grave threat to the environment and human health. The present study aims to examine the application of Tyre Derived Aggregate (TDA) in a concrete slab track and ballasted track and compare its performance in both track forms. In this study, long-term performance of slab track and ballasted track subjected to train induced loading is demonstrated based on the three-dimensional finite element modelling. The most suitable constitutive hyperelastic model for TDA has been identified. Subsequently, the most suitable position for the location of TDA is determined for both track types. A comparative analysis between slab track and ballasted track, with and without TDA, is presented in terms of stress transfer, vibration reduction and displacement (elastic and plastic). It is shown that TDA helps in reducing up to 50% vibration levels of both track types. The influence of train speed and axle load on the vertical and horizontal displacement and stress response of both track forms is shown for a large number of load cycles. Overall, it is observed that the long-term performance of TDA is better in slab track compared to ballasted track.

The cable-stayed bridge (CSB) can be considered as a masterpiece of architecture. Relatively longer spans and distinctive pylon shapes make it suitable for rapid rail transit. Pylon shape of CSB is an important consideration for modern CSB designing; lots of research has been done in the same area, but the pylon shape influence for high-speed trains remains limited. The modelling and analysis of CSB under high-speed train loads involves heavy traction force and repetitive heavy rail axle load (impact axle load), which necessitates a precise and fast analysis approach. In this research article, nonlinear dynamic analysis is performed for four distinct pylon shapes: diamond shape, H shape, A shape, and inverted Y shape for the same bridge geometry and different speed variant. A catenary cable element is used for cable modelling. The dynamic equations have been derived for the rail vehicle, bridge, and rail–bridge interaction and solved via the time integration Newton–Raphson method. Dynamic rail wagon model is formulated with a 10-degree-of-freedom system. The advanced MATLAB Simulink programme has been developed to predict the excitation experienced by the wagon for any discontinuity. The pretension in cables and the dynamic impact factor for acceleration and displacement are used to represent the bridge behaviour. The analysis results prove that the pylon with the least amount of discontinuity and the higher flexibility performs best for high-speed rail movement and resonance criteria.

Bridges in Malaysia were built to various standards in terms of bridge loading since the early 1900s. Axle Load Study in 1987 was conducted due to doubt in the existing bridge capacity to carry the current traffic load at the time. The study had led to the formulation of Weight Restriction Order (WRO) 1989 for truck legal axle weights based on Short Term Axle Load (STAL) policy, which considers HA loads with no checking done on HB load. This comprised the nation’s bridges constructed before 1972. Medium Term Axle Load (MTAL) policy was later implemented in 2003 by the introduction of WRO 2003. MTAL are loadings derived from HA load or 45 units HB loading guided along the centreline. This comprised the nation’s bridges constructed from 1972 onward. Several other studies had also been conducted in the effort to come out with Malaysian design loads for bridges. Indeed, an axle load study was conducted in 2016 to investigate the possibility of a new axle load policy. A new assessment load model to evaluate existing bridge carrying capacity is proposed in the study. The findings were accordingly gazetted in 2017 with the issuance of WRO 2017. Oblivious of these studies, many Malaysian engineers today are not informed of the rationales or basis of the practices, especially those related to bridge assessment. The purpose of this paper is to revisit these studies and discuss pertinent decisions made with regard to the national axle load policies, which were implemented through the issuance of WRO 1989, WRO 2003 and WRO 2017.

This paper presents an efficient calculation method for prediction of the steady-state response of a three-dimensional model of a railway track to a uniformly moving axle load of a train. The track model includes rails, pads, sleepers and a layered ground. Due to the sleepers, the model is periodically inhomogeneous along the track. The method is based on the so-called periodicity condition, which requires any two points of a rail, which are separated by the sleeper distance, vibrate with a well-defined phase lag that depends on the sleeper distance, load velocity and load frequency. Employing the periodicity condition, a closed-form expression is derived for a dynamic stiffness of the ground under a sleeper. This dynamic stiffness relates the forces induced by all sleepers on the ground to the displacement of one sleeper. It is the same for all sleepers. To demonstrate the calculation method, a short analysis is carried out of the dynamic stiffness and the displacements of the rails for a sub-critical velocity of the load.

The paper analyses the possibility of changing the current limits on vehicle axle loads and total vehicle weight depending on the vehicle type and the season when transporting goods by modern means of transport. The inefficient use of modern heavy trucks during the transportation of goods, forces construction organisations to violate transport regulations or to obtain special permits. The maximum permissible weight and axle load limits are set for the entire calendar period, which is incorrect because in winter the road structure becomes a "monolith" due to the frozen condition. This suggests that the seasonal characteristics of the road structure need to be taken into account when imposing the maximum limits set out in federal legislation. An important factor in the destructive effect on the road pavement is not the load and weight of the vehicle, but the pressure generated in the plane of the wheel impression on the road pavement surface. This paper presents the course of an experiment to assess the contact pressure on the pavement structure from modern vehicles in order to be able to compare the actual data with the normative data. Experimental data for the contact pressure evaluation showed results not exceeding the standard value of 0.8 MPa for the permanent road pavement type.

In this paper, effect of uncertainty of fastening system properties on the wheel/rail dynamic force (WRDF) was investigated. For this purpose, two deterministic and epistemic models of vehicle/track interaction were developed, using the finite element method. Validity of the results obtained from the models was shown through comparison between the model results and those obtained from field tests. The effects of uncertainty of fastening system properties on the WRDF in different axle loads, vehicle speeds, rail irregularities and various track maintenance conditions were derived through probability and sensitivity analyses. Using the results obtained, some contours were developed to obtain the amplification of WRDF (due the uncertainty of fastening system properties) as a function of vehicle axle load, vehicle speed and track maintenance conditions.

Axle Load Spectra (ALS) data collected from the Portable Weight-in-Motion (P-WIM) devices, provides the primary Mechanistic-Empirical (ME) traffic data input for optimal and accurate pavement design and analysis. Reliable readings from the P-WIM devices are the key factors that contribute to the accuracy of the analysis results. Therefore, this study was aimed to accurately assess the reliability and quality of the traffic data directly derived from the field data collection efforts. To accomplish this objective, the authors initially deployed P-WIM devices to US281 highway as a representative site in Texas overload corridors to collect the traffic data. The results were synthesized to compile the site-specific axle load spectra database, comprising of traffic information on the axle weights, vehicle classifications, and axle configurations. Subsequently, to assess the reliability of the collected data, P-WIM achieved traffic data were contrasted with those captured by the stationary WIM located at the vicinity of the evaluated site, using the available databases. Comparative analysis results indicated that traffic characterizations using the two WIM systems led to comparable outcomes, validating the accuracy and reliability of the P-WIM data measurements in the field. Additionally, as a practical means to investigate the quality of the recorded data, the longevity of the P-WIM piezo-sensors in several sites with different traffic patterns was investigated. Hence, the deterioration of the calibration factors over the operational life of the installed piezo-electric sensors in the field was analyzed. The post-processed results revealed that the piezo-electric sensors sustained substantial damage after nearly 37 days of operation in the field. Consequently, proper quantification of the ALS should include cross-validation assessments, as well as continuous evaluations of the calibration factors throughout the P-WIM data collection process to achieve good-quality, accurate, and reliable traffic data.

Railway lines typically use traditional sloping embankments as the principal means of track support. However, the use of Geosynthetically Reinforced Soil (GRS) systems have gained popularity as alternatives to conventional embankments, particularly for high-speed lines in Japan. This system requires less ground stabilization/improvement and less land take than conventional embankments due to its smaller base area. This research investigates the immediate and long-term settlement behaviour of a Geosynthetically Reinforced Soil with Retaining Wall (GRS-RW) system subject to cyclic loading for two track forms: a concrete slab track and a ballasted track. First, a three-sleeper concrete slab section is constructed at full-scale under controlled laboratory conditions, followed by a ballasted track. Both are supported on a 1.2 m deep subgrade and a frost protection layer in accordance with railway design standards. Two different axle load magnitudes are applied statically, and then cyclically/dynamically, using 6 actuators to replicate moving train axle loads. It is observed that the slab track performs significantly better in terms of elastic and plastic deformation under both static and cyclic loading. Overall, the amplitude of the rail displacement under an individual cycle loading was approximately 25% lower for the slab track and the amplitude of the sleeper displacement on the ballasted track was approximately 6–7 times higher.

A method of estimating traffic loads on a highway by the deformation of a bridge is called bridge-weigh-in-motion (BWIM). The conventional BWIM is based on the strain measurement of main girders. To obtain supplemental information, strains of transverse stiffeners are also measured. Previously, it has been shown that the estimation of the truck loads by the strains of transverse stiffeners solely was possible. The method is competitive from the viewpoint of cost-effectiveness. Involving the integration of time-history response of strain, the method is called BWIM by Integration Method with Transverse Stiffeners. The present study tries to modify it so as to estimate the axle loads, concluding that it works fine for the axle load as well. Yet it is noticed that when two trucks run side by side, accuracy may be deteriorated. The way to improve the accuracy in such a case is also presented.

Failure analysis and optimal redesign study of the connecting rod prototype to be used in the multi-axle steering linkage of an 8x8 Aircraft Rescue and Fire Fighting (ARFF) vehicle is reported. At the prototyping stage, the field tests showed that the connecting rod experiences a plastic deformation during a zero-speed steering manoeuvre. In order to predict the possible causes of the failure, Finite Element (FE) analyses were applied to the complete steering linkage which contains the failed rod design. Primary FE analyses showed that there are critical stress concentration regions on the rod. It was also seen that the maximum stress values at these regions are influenced by the tyre steering angle and the slope of the road surface. Subsequently, critical structural parameters having an influence on the mechanical behaviour of the part were chosen, and a parametric base model was built. Then, using DOE-RSM (Design of Experiments – Response Surface Methodology) based optimisation study, optimal values were selected within the applicable variation range. Nonetheless, by considering the form of the structure together with the loading type, it was decided that the elastic stability should also be taken into account. Although a sufficient improvement was obtained against the overload failure, the elastic stability limit remained exceeded according to the American Institute of Steel Structures (AISC) criteria. Thus, the eccentricity of the connecting rod was also decreased by employing a particular kinematic arrangement in order not to disturb the Ackermann’s rule-based synchronisation ratio of the linkage. Compared to the failed design, it was seen that von-Mises stress can be reduced by up to 66%. The results of this study showed that, factors such as wheel steering angle and road inclination-related axle load variation greatly influence the design load of the steering linkage. Field tests also indicated that, suggested design improvements such as increase in thickness and eccentricity reduction meet the strength requirements of the system.

This investigation deals with the serviceability analysis and increased axle load performance of Bridge No. 541 of UNESCO recognised Kalka Shimla Mountain Railways, which is a multi-storey arch gallery stone masonry bridge situated in the state of Himachal Pradesh, India. For this purpose, a finite element (FE) model was developed based on the drawings and reports available in Shimla Division, Northern Railways, India. Further, the results obtained from ambient vibration test (AVT) and operational modal analysis (OMA) is utilized to model update the initial FE model by modifying the mechanical properties of stone masonry. The serviceability against present-day axle loading (H Class Loading, Indian Railways) and present speed of the train is assessed. At last, a parametric study is conducted to understand the feasibility to attain higher speeds (up to 40 kmph) of the present axle load and higher axle load with different speeds of the train over the bridge to check the serviceability conditions advised in the Indian Railways code and also International codes. Finally, the study concluded that Bridge No. 541 of Kalka Shimla Mountain Railways can sustain speeds up to 40 kmph for current axle loading satisfying serviceability conditions.

The overall number of railcars recorded in the North American railcar fleet from 2010 to 2015 increased about 5%, the number of all 130 tonne (286,000 lb) gross weight railcars (heavy axle load (HAL) railcars) increased 19%. The increase in shipments in short railcars increases the loading on railway bridges, especially the 12.8-m railcars, commonly used to ship sand and cement, which is approximately a 25% increase in load per unit length compared to 16.2-m coal cars. Significant differences between maximum effects of shorter railcars and common 16.2-m railcars were predicted in analysis for bridge spans longer than 18.3 m. The differences were more prominent on spans 24.4 m and longer. This study presents analytical and measured effects of freight railcars on a two-span truss bridge, with spans of 61 m and 33.5 m, and a 35-m riveted steel deck plate girder (DPG) bridge. The investigation confirmed that short railcars cause higher load effects on main bridge components: the 35-m riveted steel DPG has 28% higher stresses at mid-span, while in the truss, the difference in stresses depends on the location of the member and ranges from 15 to 35%.

This paper gives new insights into non-linear subgrade behaviour on high speed railway track dynamics. First, a novel semi-analytical model is developed which allows for soil stiffness and damping to dynamically change as a function of strain. The model uses analytical expressions for the railroad track, coupled to a thin-layer element formulation for the ground. Material non-linearity is accounted for using a ‘linear equivalent’ approach which iteratively updates the soil material properties. It is validated using published datasets and in-situ field data. Four case studies are used to investigate non-linear behaviour, each with contrasting subgrade characteristics. Considering an 18 tonne axle load, the critical velocity is significantly lower than the linear case, and rail deflections are up to 30% higher. Furthermore, at speeds close-to, but below the non-linear critical velocity, dynamic amplification is highly sensitive to small increases in train speed. These findings are dependent upon soil material properties, and are important for railway track-earthwork designers because often 70% of the linear critical velocity is used as a design limit. This work shows that designs close to this limit may be still at risk of high dynamic effects, particularly if line speed is increased in the future.

Due to the presence in the operating fleet of freight cars with a base of over 10 m, as well as the practical impossibility of symmetrically placing loads with a weight corresponding to the nominal carrying capacity on open rolling stock, adjustments to the existing asymmetrical loading standards are necessary. To this end, it is proposed to apply a comprehensive methodology for determining the allowable parameters of asymmetrical placement of freights, based on a combination of strength criteria of the bearing elements of cars, ensuring the normative level of dynamic qualities and stability of the loaded car. The article provides an example of determining the permissible parameters of the joint lateral and longitudinal displacement of the total center of gravity of the car (ЦТгр°), loaded to the nominal capacity. According to the results of the studies to determine the allowable values of longitudinal and lateral displacement ЦТгр° with unbalanced placement within the loading platform of the car, including the presence of a joint displacement, it was found that to improve the efficiency of using freight cars with an increased base, it is advisable to update the current offset standards of ЦТгр°. It is recommended to take the values of longitudinal displacement ЦТгр° for cars with a body base of 14.6 and 19.0 m respectively 1.46 and 2.11 m for freight with a total weight of 50 tons; 1.10 and 1.43 m for freight with a total weight of 60 tons; 0.22 and 0.28 m – for freight with a total weight of 67 tons. When placing freights with a total weight of over 67 tons with a height of center of gravity of 2.0–2.2 m on 4-axle freight cars with an axle load of 230.5 kN without limiting the permissible driving speeds, it is recommended to use a graphical method for determining the joint (longitudinal and transverse) displacement ЦТгр°. With an increase in the joint displacement parameters ЦТгр°, it will be necessary to limit the speed of the car in the curved sections of the track and to the lateral direction on the turnouts.

With ongoing massive investment in the field of autonomous vehicles, fully autonomous self-driving vehicles are set to become a reality soon. Despite the benefits in traffic safety and economy, the potential effects of autonomous vehicles, especially autonomous trucks, on transportation infrastructure remain to be determined. In this study, a finite element model was developed based on a typical flexible pavement structure. The effects of autonomous trucks’ lateral distribution within the lane with respect to rutting depth and fatigue damage were estimated by finite element analysis under certain environmental condition. Characteristics of the pavement structure and environmental condition have been collected and presented in this paper. Four possible lateral control modes on managing autonomous trucks’ lateral distribution were proposed, listed as zero-wander mode, uniform mode, double peak Gaussian mode, two-section uniform mode. Considering the difference between autonomous trucks and human-driven trucks, the ratio of autonomous trucks was also evaluated. Based on the simulation results, it has been confirmed that, if controlled appropriately, autonomous trucks could be highly beneficial to asphalt pavements for wider using of pavement. Conversely, if without appropriate lateral control, the effect of autonomous trucks on the typical flexible pavement life could be negative, owing to repeated single point load caused by lane centering and keeping. For example, the uniform mode, double peak Gaussian mode and two-section uniform mode all throw positive effect on the pavement. On the contrary, under the zero wander mode, the time when the rutting depth of the proposed pavement reaches 15 mm (defined as maintenance year) may advance by 1.56 years and fatigue damage at the bottom of asphalt layer increases by 146%. Compared with the normal situation nowadays, the two-section uniform distribution of autonomous trucks, the best performing control mode, delays the maintenance year by 2.3 years. From the aspect of fatigue, a much uniform distribution curve of fatigue within the lane can also be found under this mode. When all trucks’ lateral positions were in control, the two-section uniform mode could reduce the fatigue damage by up to 35% under repeated standard axle load on the flexible pavement. Finally, a framework of dealing with the lateral control was proposed as a reference for different conditions, such as asphalt pavement structures and materials.

Industry 4.0, or the fourth industrial revolution, is the current trend of automation and data exchange in manufacturing technologies. Even though Industry 4.0 emerged as a manufacturing initiative, the idea of bridging digital and physical systems can be expanded beyond the manufacturing industry. “Railroad Infrastructure 4.0” is thus proposed in this study to revolutionize the maintenance operations of the railroad industry. In North America, most primary freight and passenger rail corridors are constructed using ballasted track. One of the primary maintenance activities is to ensure the ballast is performing adequately. Being able to monitor the ballast condition and conduct tamping operations (e.g. maintenance activities) at optimal intervals can increase the safety and efficiency of railroad operations. Previously, techniques such as ground penetrating radar (GPR) and Matrix Based Tactile Surface Sensors (MBTSS) have been used to assess the condition of ballast, but these investigative tools lack the capability of automatically and continuously monitoring the track system. Researchers at the University of Illinois at Urbana-Champaign and the University of South Carolina have developed a non-intrusive method as a key component of Railroad Infrastructure 4.0 to continuously quantify ballast pressure distribution (i.e. ballast condition) under the sleeper (also known as a “crosstie”). This method innovatively uses the bending moment profile across the concrete sleeper, and the approximated rail seat loads as inputs, to back-calculate the ballast support condition through the use of an optimization algorithm. The ballast support condition assessment system that was developed has been validated for accuracy from extensive laboratory experimentation. The laboratory validated system was deployed in the field on a Class I heavy axle load (HAL) freight railroad in the United States to continuously monitor the ballast pressure distribution beneath concrete sleepers in real-time under revenue service operating conditions. The evaluation of ballast pressure distributions between adjacent sleepers as well as tonnage accumulated are also included. To better quantify the variation of ballast pressure beneath the sleepers, the Ballast Pressure Index (BPI) is also proposed. The information presented in this paper demonstrates the concept and potential of Railroad Infrastructure 4.0 as a future framework for railroad maintenance planning and management.

In accordance with the draft Long-Term Development Program of the JSC “Russian Railways” until 2025, the main driver of growth in freight turnover in this perspective will be a further increase in the transportation of hard coal. It will occur both due to the growth of coal production in Kuzbass and due to the development of new coal deposits. For the period up to 2025, the increase in coal loading by 4 – 5 % per year is predicted on rail transport. Under these conditions, it becomes necessary to increase the capacity of the transport complex, especially the carrying and transport capacities of the Eastern Operation Area.The article presents the methodology for calculating economic effect of increasing the carrying capacity of the site during operation in cars with increased axle load. The scope of this methodology is specific areas (sections), taking into account their technical, operational and economic parameters.Variant calculations were made, the results of which showed that an increase in the carrying capacity of a section with an increase in the mass of a train formed from cars with increased axle loads does not always give a significant positive effect in terms of value for the infrastructure owner. Positive effect of the increase in carrying capacity in the form of additional profits from the additionally used traffic volume in the evaluated variant can be taken into account in the following cases:- operation of large-capacity cars on freight-intensive sections where there is a lack of carrying capacity in the billing period, i. e. the carrying capacity of the section is less than its required value;- exceeding the freight charge for the additional volume of freight carriage incurred transportation costs, i. e. if the tariff compensates for at least the dependent part of the cost of additional volume transportation.Positive economic effect of the increase in carrying capacity in the form of increased money flow is achieved if the profit from the additional traffic volume in the direction exceeds the additional costs associated with changing the technology for servicing the traction arms while promoting high-weight trains formed from cars with increased axle loads. In other words, if there is no increase in the value of the indicator of mileage (in section-km) per unit of transport work, and the unit cost of maintaining one section with a new technology for servicing traction arms.

Мета. Визначення впливу поздовжнього й поперечного зміщення центра тяжіння великовагового вантажу на платформах, з урахуванням швидкості руху, на основні динамічні показники – максимальні коефіцієнти динамічної добавки обресорених і необресорених частин, максимальне відношення рамної сили до статичного осьового навантаження, коефіцієнт стійкості колеса від сходження з рейок. Методика. За основу дослідження взято метод математичного та комп’ютерного моделювання динамічної навантаженості платформи з використанням моделі просторових коливань зчепу з п’яти вагонів і програмного комплексу, розробленого в галузевій науково-дослідній лабораторії динаміки й міцності рухомого складу (ГНДЛ ДМРС). Теоретичні дослідження проведені за умови руху платформи моделі 13–401 з типовими візками 18–100 зі швидкостями в інтервалі від 50 до 90 км/год по кривих із радіусами 350 й 600 м, із підвищеннями зовнішньої рейки 130 і 120 мм відповідно. Результати. Подано аналіз теоретичних досліджень динамічних якостей рухомого складу на прикладі платформ. Розрахунки проведені з використанням пакета прикладних програм. У ході виконання теоретичних досліджень і після проведення моделювання з урахуванням процесів коливання вагона-платформи й вантажу, за наявності поздовжнього й поперечного зміщення його центра тяжіння, отримано залежності основних динамічних показників з огляду на величину швидкості руху. Наукова новизна. Для визначення динамічної навантаженості вагона платформи, із застосуванням математичної моделі зчепу з п’яти вантажних вагонів, досліджено вплив зміщення у двох напрямках від центральної осі симетрії центра тяжіння великовагового вантажу з огляду на величину швидкості руху по кривих ділянках колії малого й середнього радіуса. Практична значимість. У результаті проведених теоретичних досліджень обґрунтовано рекомендації стосовно максимально можливих величин зміщення центра тяжіння великовагових вантажів під час їх транспортування на вагонах-платформах., Purpose. The article deals with the determining the influence of the longitudinal and lateral shift of gravity centre of the heavy load on the flat wagons, taking into account the travel speed based on the main dynamic indicators – the maximum coefficients of the dynamic supplement of spring-suspended and unsprung parts, the maximum ratio of frame force to static axle load, the wheel derailment safety factor. Methodology. The study was carried out using the method of mathematical and computer simulation of the dynamic loading of flat wagons based on the model of spatial oscillations of five coupled wagons and the software complex developed in the branch research laboratory of the rolling stock dynamics and strength (BRL RSDS). Theoretical studies were carried out during the movement of the model 13-401 flat wagon on typical 18-100 bogies with speeds in the range from 50 to 90 km/h in curves with radii of 350 and 600 m, with 130 and 120 mm canting, respectively. Findings. The paper presents the analysis of theoretical studies of the rolling stock dynamics on the example of flat wagons. The calculations were carried out using an application software package. In the course of performing theoretical studies and after simulation, taking into account the processes of oscillation of the flat wagon and load in the presence of longitudinal and lateral shift of its gravity centre, the dependences of the main dynamic indicators were obtained with regard to the magnitude of the travel speed. Originality. Using the mathematical model of the five coupled wagons, the effect of shift in two directions from the central symmetry axis of the heavy load centre was studied with regard to the travel speed along the curved track of small and medium radius in order to determine the dynamic loading of the flat wagon. Practical value. As a result of the above theoretical studies, the recommendations on the maximum possible values of the centre shift of heavy loads during their transportation on flat wagons are substantiated and proposed., Цель. Определение влияния продольного и поперечного смещения центра тяжести тяжеловесного груза на платформах, с учетом скорости движения на основные динамические показатели – максимальные коэффициенты динамической добавки обрессоренных и необрессоренных частей, максимальное отношения рамной силы к статической осевой нагрузке, коэффициент устойчивости колеса от схода с рельсов. Методика. Основой исследования является метод математического и компьютерного моделирования динамической нагруженности платформы с использованием модели пространственных колебаний сцепа из пяти вагонов и программного комплекса, разработанного в отраслевой научно-исследовательской лаборатории динамики и прочности подвижного состава (ОНИЛ ДППС). Теоретические исследования проведены при движении платформы модели 13–401 с типичными тележками 18–100 со скоростями в интервале от 50 до 90 км/ч по кривым с радиусами 350 и 600 м, с возвышением наружного рельса 130 и 120 мм соответственно. Результаты. Представлен анализ теоретических исследований динамических качеств подвижного состава на примере платформ. Расчеты проведены с использованием пакета прикладных программ. В ходе выполнения теоретических исследований и после моделирования с учетом процессов колебания вагона-платформы и груза, при наличии продольного и поперечного смещения его центра тяжести, получены зависимости основных динамических показателей на основании величины скорости движения. Научная новизна. Для определения динамической нагруженности вагона-платформы, с применением математической модели сцепа из пяти грузовых вагонов, исследовано влияние смещения в двух направлениях от центральной оси симметрии центра тяжести тяжеловесного груза с учетом величины скорости движения по криволинейным участкам пути малого и среднего радиуса. Практическая значимость. В результате проведенных теоретических исследований обоснованы рекомендации относительно максимально возможных величин смещения центра тяжести тяжеловесных грузов при их транспортировке на вагонах-платформах.

A 762‐mm‐diameter pipe 1,886 km long was installed to transfer crude oil in the USA from North Dakota to Illinois. To investigate the impact of construction and restoration practices on long‐term soil productivity and crop yield, vertical soil stresses induced by a Caterpillar (CAT) pipe liner PL 87 (475 kN vehicle load) and semi‐trailer truck (8.9 kN axle load) were studied in a farm field. Soil properties (bulk density and cone penetration resistance) were measured on field zones within the right‐of‐way (ROW) classified according to construction machine trafficking and subsoil tillage (300‐mm‐depth tillage and 450‐mm‐depth tillage in two repeated passes) treatments. At 200 mm depth from the subsoiled surface, the magnitude of peak vertical soil stress from trafficking by the semi‐truck trailer and CAT pipe liner PL 87 was 133 kPa. The peak vertical soil stress at 400 mm soil depth appeared to be influenced by vehicle weight, where the Caterpillar pipe liner PL 87 created soil compaction a magnitude of 1.5 greater than from the semi‐trailer truck. Results from the soil bulk density and soil cone penetration resistance measurements also showed the ROW zones had significantly higher soil compaction than adjacent unaffected corn planted fields. Tillage to 450 mm depth alleviated the deep soil compaction better than the 300‐mm‐depth tillage as measured by soil cone penetration resistance within the ROW zones and the unaffected zone. These results could be incorporated into agricultural mitigation plans in ROW construction utilities to minimize soil and crop damage.

Introduction. Law changes concerning road service and cargo traffic rules lead to the necessity of maximal axel load calculating during the cargo transportation. Such problem is particularly important while friable cargo transporting, as accelerating or breaking cargoes (road-trains) at a longitude inclination or turning could provoke partial lading shift towards the cargo axles. The paper demonstrates the results of friable cargo offset experimental research (grail, broken stone) while transporting. Moreover, the authors also describe influence of the friable cargo offsets on freight transport axle load changing.Materials and methods. The research measured friable cargo level in the road-train semitrailer before and after the experiment, axle weighting and the full mass weighting. In addition, the authors made video filming of friable cargo offsets.Results. Analyzing the experimental data of axial weighting, the authors noted that during the friable cargo transportation, the cargo was redistributed inside the semitrailer and such process led to a change in axial loads of the road-train. The axel load changing was not included into the measurement accuracy and was about 1,4 – 4,9%. Another argument of the friable cargo shift inside the semitrailer was cargo video filming while transporting. Video analysis showed that both chip stone and gravel was moving inside the semitrailer while the road-train accelerated motion.Discussion and conclusions. As a result, the research proves the experimental verification of the friable cargo offset over the semitrailer ramps while braking. Such offsets lead to the changing of freight transport axle load.

Owing to increases in route traffic, axle load, and incompatible combinations of wheel-rail profiles in freight wagons, the Iran railway network has encountered a tremendous increase in localized wheel flange wear. Thus, a strategy was applied to select a new wheel profile to improve wheel-rail interaction and decrease overall localized wheel flange wear. In this research, a practical method was applied for an optimal selection of a wheel profile to minimize wheel wear for three types of freight bogies commonly employed for freight open wagons, including the three-piece 18100, Y25, and H665 series. The research procedure to select the final candidates was based on a wear behaviour study of verified bogie vehicles’ numerical models in operation, as equipped with various wheel profiles via conventional wheel-rail wear models. Then, comprehensive field tests were conducted to monitor the flange wear depth and total wear rate of the final wheel profile candidates in operation conditions, from the aspects of one and multiple wheel-rail contact point distribution, wear rate, and stability of the worn wheel profile for 56,500 km. Eventually, the optimal wheel profile was recommended, in consideration of the population of each bogie type. Some technical and field study aspects of the work were also discussed.

The ground vibration wave induced by the viaduct section of the heavy freight wagons is transformed into the ground vibration problem under the condition of point source excitation after it is transmitted to soil through pier. When the speed and axle load of wagon become larger and larger, the impact on the surrounding buildings will also increase. In this paper, the ground vibration around Shenshan Village in section of Shuo-Huang railway line is monitored and numerical analyzed; the 3D numerical model of the Bridge-Pier-Field-House system is established. The relationship between peak vibration velocity (PPV) and the distance to the pier caused by heavy freight wagons at different speeds and different type of wagons is analyzed. The power function relationship between the two when measuring line perpendicular to the centerline of railway is verified. Based on the modified Sodev’s equation, the relationship between PPV of ground points and wagon speed, axle load, and soil properties is proposed, and the value of every parameter in the formula is discussed in detail. The concept of energy index is put forward for the first time in the formula, and the relationship between energy index and wagon speed and wagon weight is analyzed by regression analysis. The accuracy of the calculation model and prediction formula is verified by comparing field test results; an analytical method is proposed to predict the ground vibration induced by viaduct.

The French railway network includes over 30 000 km of railway tracks and more than 5000 metallic bridges. Some of them have been in service for over a century and they need adapted measures for their maintenance. Due to the increase of rolling speed and axle load, fatigue is one of the main phenomena to take into account in order to extend the safe service life of metallic bridges. In order to better understand how old bridges behave, a specific Agressiveness Index (AI) has been defined and enables to compare the effect of different rolling stocks on the mechanical behaviour of stringers. This index was tested fot different historical type trains. For these calculations, a set of real stringers was considered, including different periods of construction, different spans and inertias. The SIA fatigue curve with Δσc=80MPa has been chosen taking into account historical allowable fatigue stress. The calculation model of stresses in stringers of this study shows a good agreement with the SNCF historical inventory of repairs.

The railway track must ensure safe railway transport with the maximum speed and axle load that can be applied to the track. Hungarian railway infrastructure managers (eg. MAV, GYSEV) are spending large amount of money on railway superstructure and substructure diagnostics and on network analysis based on diagnostic results. Taking into account the results of the measurements, repairs of local defects that pose a direct threat, as well as the planning of comprehensive reconstructions are carried out. This article reviews the railway track diagnostic methods used (or to be applied in the near future) in Hungary, based on the results of which military and civil accident prevention analyses can be made.

The dynamic response of the subgrade surface under moving train loads provides information for subgrade settlement prediction, condition evaluation and so forth. In this paper, a 3D dynamic finite element (FE) model that considers the interactions among the wagon, track and subgrade was built. Then, the irregular vertical track spectrum of the three major lines in China was applied to simulate track irregularity. Through numerical calculation, the influence of vertical track irregularity on the dynamic stress of subgrade surface was investigated. The distributions of peak dynamic stresses at three subgrade surface locations (under each of the two rails and at the track center) along the track under the passage of trains with various axle loads were statistically acquired. The normal distributions of the peak dynamic stresses on the subgrade surface were verified. The maximum peak dynamic stresses were forecasted. The results indicated that the dynamic stresses on the subgrade surface were asymmetric along the center of subgrade surface due to the random distribution of track irregularities, and the peak dynamic stresses were found to follow a normal distribution. With the increase of axle load, the dispersion of peak dynamic stresses increased gradually, and the distribution curve of peak dynamic stresses gradually became steeper. The computed peak dynamic stresses aligned well with the field test data, indicating that the 3D dynamic FE model and statistical analysis method were reasonable. The research results will provide a basis for the reliability analysis of the dynamic deformation and accumulated settlement of subgrade surface.

A six-wheel driving system with a variable wheelbase is proposed to improve the passing ability of unmanned vehicles. As the first step, the effect of the wheelbase variation on the axle load distribution is analyzed. Next, the relationship between the wheelbase variation and rolling resistance is obtained by numerical calculation combined with the theory of terramechanics, and it shows that the traction performance of the vehicle can be optimized by adjusting the wheelbase. Considering the deformation of tires and soil, the mechanism of the effect of the change in wheelbase on the ability of the vehicle to overcome an obstacle and cross a trench is studied, and a variable-wheelbase strategy for a vehicle overcoming an obstacle and crossing a trench is then proposed on the basis of theoretical calculations. Finally, the rationality of the variable-wheelbase strategy is verified in simulation experiments.

As one of the active safety technologies, stability control of vehicles has recently received great attention. In order to improve the handling stability of distributed drive electric vehicles under various extreme conditions, a direct yaw moment control (DYC) method based on a novel fuzzy sliding mode control (FSMC) is proposed. First, a linear 2DOF reference vehicle model as ideal value reference, a 7DOF vehicle model used for sideslip angle estimation, an electric-driving wheel model used to provide tire motion parameters based on CarSim platform are established. Then, FSMC is designed as the core decision-making layer of the control method to calculate the required additional yaw moment on the premise of estimating the sideslip angle. Four hub motors are allocated by the distribution method based on axle load proportion. Finally, under two typical working conditions, the four hub motors are allocated. Compared with traditional sliding mode control (SMC), the results show that FSMC can not only maintain vehicle stability more effectively under different working conditions, but also greatly reduce the occurrence of buffeting phenomenon, which has practical significance for engineering applications.

In the areas which have rich rain and poor drainage, there may be obvious water damage existed in the interlamination of ballastless track. The damage is mainly caused by repeated hydraulic fracturing. Aimed at this problem, the calculation model of water pressure under the train load was established on the basis of fluid-structure interaction theory, and the influence of crack geometry and train operation condition on water pressure were analyzed. The results show that, when the train is close to and far away from the location of the crack, the water pressure changes periodically under the train load, and the pressure peak occurs at the crack front. Simultaneously, the positive and negative pressure may both exist in the crack. The crack geometry affects the distribution of water pressure significantly, the value of water pressure is inversely proportional to the vertical opening of crack, and proportional to the cubic polynomial of horizontal crack depth. The water pressure increases firstly with the increase of longitudinal crack length, then decreases gradually and tends to be stable finally. The train operation condition is also an important factor affecting the distribution of water pressure, the value of water pressure is linear with the axle load, and proportional to the square of train speed. These research results will provide a hydraulic boundary condition for further study of water damage mechanism.

A new track-multilayer ground model was established to investigate railway subgrade dynamic responses induced by moving train load in this paper. The ground structure was modeled by an elastic layer overlying an unsaturated porous elastic half space. The dynamic governing equations of the three-phase porous medium, which are easy to be degraded to Biot's theory, were derived with consideration of both viscous drag and inertial coupling between pore fluids and soil skeleton as well as capillary pressure. The model solutions were obtained based on dynamic stiffness matrix method and Fourier transform and introducing corresponding boundary condition. The vertical displacement on the subgrade top surface and the pore water pressure along the depth were studied. The numerical results show that the effects of saturation, vehicle speed, train axle load and subgrade bed material properties on the subgrade responses are significant.

This paper presents a summary of more than two decades of heavy axle load (HAL) railway subgrade research conducted at the Facility for Accelerated Service Testing (FAST). Railway subgrade, if inadequate and not reinforced/improved, can deform and fail progressively, causing significant track geometry degradation under HAL train operations. To understand how railway subgrade behaves under HAL and develop guidelines for design, maintenance and remediation, a number of tests were conducted in multiple phases at FAST to determine how a “soft” subgrade test section would affect track performance and to evaluate remediation methods that can be used to improve soft subgrade support for HAL train operations. Since its inception in the early 1990s, this subgrade testing program has produced a body of knowledge about railway subgrade behavior under 35.4-tonne axle loads. In addition to generating track degradation and maintenance demand data, the testing program provided valuable insight into the relationship between subgrade behavior and track performance. Results were obtained to understand how wheel loads were transferred to the subgrade, subgrade failure mechanisms, and how various soft subgrade remediation techniques performed.

The determination of traffic volume in asphalt pavement design has not considered the effects of seasonal variability on vehicle axle loads in China. By analyzing the effects of seasonal variation on the axle loads, formulas for the conversion of modified axle load to traffic volume have been derived and presented, in accordance with specifications in China. This study includes the following: derivation of formulas for converting modified axle loads to traffic volume, classification of 3 different seasons, determination of seasonal distribution and influencing coefficients, and application of modified axle load conversion formulas, among others. By comparison of results between modified and unmodified formulas applied in a sample asphalt pavement design in Harbin, China, the study demonstrates that the modified axle load conversion formulas are scientific and rational. The results of asphalt pavement design obtained using the modified axle load conversion formulas increase the thickness and whole strength of the asphalt pavement structure; in addition, it can more efficiently satisfy the requirements of an actual vehicle running on the pavement. Keywords: Traffic volume, Vehicle axle load, Axle load conversion formula, Seasonal influence, Modified formula

By virtue of its high speed, steadiness, and quality experience, high speed railway (HSR) has grown rapidly. During that development, problems such as dynamic irregularity in the bridge–embankment transition have been exposed and have aroused keen attention. To study dynamic performance in bridge–embankment transition, field dynamic tests under 120 high speed vehicles running at speeds of 5–360 km/h were carried out. Then, processed signals were obtained from the original signals by a series of signal processing methods such as wavelet soft threshold filtering, Newton-Cortege integration, and five-thirds smoothing. Moreover, the statistical test data were analyzed in the time/frequency domain to obtain the frequency characteristics, the rules governing changes in dynamic responses along the longitudinal and depth directions, and the rules governing changes in dynamic responses with train speed, train running direction, vehicle axle load, and adjacent load. The results showed that (i) the concentration range of the first two main frequency was generally 0–50 Hz, (ii) particular attention should be paid to sections 7.5 m, 13 m and 25 m from the abutment tail, and (iii) importance should be attached to the bed surface layer. As well, 275 km/h was the critical train speed and acceleration was a sensitive dynamic index. Finally, the dynamic responses showed that a bridge–embankment transition with the subgrade filled with graded gravel + 5% cement satisfied design and operation requirements at speeds of 5–360 km/h.

This paper introduces the situation of existing railway lines and the importance of developing heavy load transportation in China. The problems existing in the bridge, culvert, roadbed, station yard etc. are analyzed with 27t axle load running on the existing railway lines, and put forward some targeted reform measures.

The increase of axle load and train speed would cause intense wheelrail interactions, and lead to potential vibration related problems in train operation. For the low-frequency vibration reduction of a track system, a multi-layer track structure was proposed and analyzed theoretically and experimentally. Firstly, the analytical solution was derived theoretically, and followed by a parametric analysis to verify the vibration reduction performance. Then, a finite element simulation is carried out to highlight the influence of the tuned slab damper. Finally, the vibration and noise tests are performed to verify the results of the analytical solution and finite element simulation. As the finite element simulation indicates, after installation of the tuned slab damper, the peak reaction force of the foundation can be reduced by 60%, and the peak value of the vertical vibration acceleration would decrease by 50%. The vibration test results show that the insertion losses for the total vibration levels are 13.3 dB in the vertical direction and 21.7 dB in the transverse direction. The noise test results show that the data of each measurement point is smoother and smaller, and the noise in the generating position and propagation path can be reduced by 1.9 dB–5.5 dB.

Overloaded vehicles is one of the main problemsthat cause premature failure in road infrastructure. This paper presents an analysis of overloaded vehicles'effect on flexible pavement based on historical weigh-in-motion data. Thisarticle highlights the potential use of weigh-in-motion (WIM) data in pavement design by addressing the overload, the percentage of overloading, and axle load distribution. The percentage of overloaded vehicles can reach more than 80% of the total number of trucks and maybe one of the substantial factors that reduce pavement's service life. The actual traffic load is presented in the form of distribution for each type of axle load (axle load spectra) and the Vehicle Damage Factor (VDF) for each truck type. The effect of overload on the flexible pavement's design life is estimated by using the Cumulative ESAL comparison and Pavement Damage Ratio. Both analyses show that overload vehicles significantly decrease the pavement design life up to nearly half of the pavement life.

The existing fatigue assessment approaches were mainly conducted on the component level. The interaction of local component damage and the global response cannot be well addressed. In this study, three-dimensional (3D) fatigue crack propagation analysis approach based on global-local numerical model was implemented, and examined to be accurate and effective through a series of systematic experimental data obtained by Fisher. Afterwards, the approach was introduced into a typical steel truss bridge for realizing more refined fatigue assessment from the global structural level. The fatigue performance of the longitudinal steel welded beam in the steel truss bridge was investigated based on global-local model and local model respectively. It was found that there is no difference in terms of the fatigue crack growth mechanism between the simulation between global-local model and local model due to that the stress level of the whole structure is relatively low. At last, the effect of heavy haul train operation on the fatigue performance of the steel truss bridge was analyzed. It was observed that the residual life of the longitudinal steel welded beam would have an obvious reduction when the axle load was increasing. The research work in this study presents a technical solution for the fatigue assessment of the global structure and can provide beneficial reference for relevant practical engineering projects.

With urban rail transit developing fast, there is an increasing demand for ride comfort and reduction of vibration and noise. Metro being the main public transportation facility of urban rail transit in China, faces more severe challenges. Metro tracks use a range of different vibration isolating ballasted track structures. Environmental vibration along metro lines is controlled by using so-called vibration isolating track structures. In doing so, many problems arise in the train track system of metro lines, such as strong vibration and excessive wear of wheel/rail systems, possibly causing vibration fatigue and noise. Embedded track is used as an option to reduce vibration and noise, usually applied for tramways. When applied to metro lines, embedded track faces challenges due to high speed, large axle load and more complex line conditions. When applied to metro lines, the acoustic characteristics of embedded track need to be re-evaluated. These characteristics were investigated through a combined method of simulation and experiment. In this study, the wheel and track acoustic radiation of the embedded track designed for metro was prediction and compared to that of a common track. The study can provide a basis for the application of embedded track in metro systems.

Traffic counts collect information that is valuable, for example, in bridge and road design or maintenance processes. The average daily traffic volume is often the most collected measure of vehicular traffic, which is used in the design or assessment of major highways. Permanent control stations, situated in key locations of the highway network, gather data the entire year. However, one of the disadvantages of traffic count data is that most counters used, do not measure total vehicle weight and axle load data. Traffic counts display only the classification of vehicles, traffic volume, average daily traffic, and annual average daily traffic. Axle loads on the other hand are required, for example, as input in the design of pavement and new bridges, and the reliability assessment of existing ones. Weigh-in-motion (WIM) systems are usually used to collect vehicle load data. The State of Mexico (in central Mexico) has 115 permanent vehicle counting stations with 745 traffic counting points in its federally administered road network. However, due to the lack of WIM stations, it is not possible to obtain axle load data. In this paper, a Bayesian Network (BN) quantified with data from WIM stations in the Netherlands is used to describe the weight and length distribution of heavy vehicles registered in the permanent vehicle counting stations of the State of Mexico federal highways. The Dutch and Mexican vehicle types are matched according to similar characteristics. Later, synthetic WIM observations from the BN model are analysed through extreme value theory and vehicle loads with selected return periods are computed for all study counting points. The outcome is a mapping methodology with a linked database. The traffic volumes and extreme loads can then be easily found and compared with other highways in the network. This work shows that hazard maps can be implemented to provide importantly and summarized information to understand the risks of extreme traffic loads and to help in the reliability assessment and maintenance strategies of pavements and bridges.

Ballast degrades through wear and breakage due to the cumulative actions of traffic. This study evaluated ballast degradation using the Los Angeles abrasion (LAA) and cyclic loading tests, changes in the ballast aggregates shape indexes (form, angularity, surface texture and volume) were also evaluated using image analysis techniques. A typical freight train with an average speed of 120 km/h and 30 tonnes capacity was simulated for the cyclic loading test. Series of LAA and cyclic loading tests were conducted on separate samples of the same gradations, and the changes in the aggregates shape indexes were determined using the Aggregate image measuring system (AIMS) package and a 3D laser scanner before and after each of the tests. The image-based assessment revealed that ballast degradation is related to the particle edge breakage and surface wear. The overall experimental results showed that ballast degradation is more profound in the ballast early stage of service, and the degradation index has a good correlation with the changes in aggregate shape indexes. The results also revealed that the two tests gave different degradation indexes, hence a relationship between the ballast degradation index and the number of load cycles with the number of LAA drum turns is proposed to reflect the effect of the number of train’s axle load cycles on ballast degradation.