China Railway Freight Research Articles

Will China complete the 4.79-billion-ton railway freight transportation goal: An incremental potential research from the supply side

In 2018, China's State Council proposed a 30% increase in railway freight volume (RFV) to 4.79 billion tons in 2020 over 2017. Subsequently, more than 30 provinces and cities in China have issued corresponding transportation structure adjustment plans, but the completion of this task has not been very smooth. The growth rate in 2019 is slower than that in 2018, and the incremental task in 2020 still remains 42.7%. China's railway freight transportation capacity (RFTC) used to be in short supply for a long time, which has only eased in recent years. In order to explore the adaptation of China's current RFTC and incremental targets, and fully tap RFTC potential to formulate reasonable freight increment policies in the future, this article combines the simultaneous production and consumption feature of transportation sector and SBM-GRS (slack based measure-general returns to scale) data envelopment analysis to measure China's RFTC surplus space. The study found that from the supply side the incremental potential of China's railway freight turnover (RFT) is greater than that of RFV, which is caused by the imbalance of regional railway freight transportation. If the current RFV goal was replaced by RFT, RFTC input would save about 3%. This article suggests that China's future railway freight increment policy should take into account the regional imbalance of bulk cargo transportation, pay more attention to the growth of RFT, actively take advantage of railway container long-distance transportation, and make full use of overall RFTC.

Evolution of spatial and temporal patterns of railway container transportation: A case study of China cities.

The healthy development of railway container transport is an important part of railway freight transport and is key for promoting the green transformation of China's transport and supporting a new pattern of transport development. In this study, railway container handling station (RCHS) data, kernel density analysis, standard deviation ellipse, Herfindahl-Hirschman index (HHI), trend surface analysis (TSA), and R index were applied to examine the evolution characteristics of container transport patterns after the market-oriented reform of China's railway freight transport in 2013. The results are as follows: First, the overall scale growth trend is obvious, and the double-center effect of transport scale on the Bohai Rim region and Chengdu-Chongqing Economic Zone is evident, with the transport center of gravity moving northward. Second, the amount of attraction/occurrence is consistent in spatial distribution, and the aggregation effect of both is similar, essentially exhibiting a tendency of being high in the northwest and low in the southeast. Third, the pattern of "export-oriented in the north and import-oriented in the south" has taken shape; nearly half of cities in China have stable traffic functions, stable traffic supply, and demand relationships, and the change of functions shows that the industrial structure is constantly upgrading. This study elucidates the pattern of railway container transport in cities in China and provides empirical guidance for adjusting the functions of urban freight transport, thereby promoting the healthy development of urban freight transport and optimizing urban transport planning.

Prediction model for railway freight volume with GCA-genetic algorithm-generalized neural network: empirical analysis of China

Reasonable and scientific prediction for railway freight volume has an important impact on railway network planning and railway transportation resources allocation. However, to predict the future railway freight volume is complicated and difficult, because it is influenced by many factors, such as macro economy, industrial structure, and supply capacity, etc. In this paper, an improved prediction model is proposed, named as GCA-GA-GNN. GCA is short for grey correlation analysis, which was adopted to select the key factors which have great influence on railway freight volume instead of subjective factors. GNN is the main body of the prediction model, which combines grey prediction model and neural networks to take the advantages of linear and nonlinear modeling capabilities. Moreover, genetic algorithm is used in GNN to improve calculating speed. Then, the validity of the model was verified by the empirical case of China. The results of five different prediction models showed that the model proposed in this paper has faster convergence speed and higher prediction accuracy. Moreover, according to the downward trend of China railway freight volume from the year 2017 to 2020, some suggestions are proposed to reverse the downward trend and increase railway corporation’s profits.

BP Neural Network Based Optimization for China Railway Freight Transport Network

In order to optimize the railway freight transport network, integrate the limited transport resources and overcome the current problems existing in the traditional transport organization, in this study, we propose a three-layer railway freight transport network system, analyze its hierarchical structure and describe the respective function orientation of the railway freight stations in different layers. Then we design a BP neural network model with adaptive learning algorithm and momentum BP algorithm to classify the railway freight stations into three layers. Finally, an empirical case study is presented to test the feasibility of the BP neural network. The simulation result indicates that the BP neural network model can classify the railway freight stations into three layers under relatively high training accuracy.

Prediction Models for Railway Freight Volume Based on Artificial Neural Networks

The current China railway freight transport has always been faced with the situation of limited transport resources. Many relative studies have been done to solve the problem of resource shortage. And railway freight volume prediction is the basis of all these studies. With accurate volume prediction, railway freight transport administrations can precisely allocate the transport resources, such as wagons and locomotives. In order to overcome the limitations of traditional prediction methods, in this study, we design four artificial neural network models for prediction, including BP neural network model, linear neural network model, RBF neural network model and generalized regression neural network model. The results of simulation and comparison show that all these models can reach high prediction accuracy and generalized regression neural network has both higher prediction accuracy and better curve fitting capacity compared with other models.

China's Railway Transportation Network Christopher Research

Based on China railway freight transportation network, this paper builds the railway transport network. Then, according to uneven distribution of capacity and the problems of asymmetric information, low efficiency of railway freight transportation, the paper puts forward the resolving method by whole network Christopher of the social network analysis. In this paper, according to the China railway transportation network statistics results of China railway freight transportation network Christopher, whole Christopher coefficient is 0.39. Originally, the study also concluded that the degrees of freight volume, using to finding out the problems of multiple nodes, sorting and take the strategy to improve group coefficient better. All in all, this paper solved the problem of China railway network understanding and gave advice for improving China's railway transportation economic benefits.

Construction of China Railway Freight Car Color Coating Genealogy

The paper analyzes existing problems in China's freight car color coating, compares the gap between same products abroad, comprehensively analyzes relevant factors which affect freight car coating, uses system theory combined with specification of safe color, visual safety psychology and coating material technology and takes requirements such as type, structure, safety and corporate image into consideration to establish China's railway freight car color coating genealogy. It provides systematical advices for China's railway freight car color coating design and solves problems like single and disorder coating color, poor indicative of safety feature to improve the level of China's railway freight car coating design.

The Design and Implementation of Railway Freight Applications on China's Railway Freight Data Grid Platform

The Design and Implementation of Railway Freight Applications on China's Railway Freight Data Grid Platform

Failure Analysis on Bearings of Railway Freight Cars with Tilting Bogie

Causes are investigated on earlier failures of the bearings for China railway freight cars with tilting bogie. Through dissembling failure objects, checking manufacturing qualities and calculating rolling contact fatigue (RCF) stresses, it reveals that RCF plays a key role to the bearing failures. Design mismatch of the RCF stresses between outer and inner rings is main cause of the earlier failures of bearings. It is further verified that the present earlier failures of the bearings on the cars with tilting bogie than others on cars without tilting bogie is a reasonable phenomenon, because the wheelsets on the cars with the tilting are subjected to more severe loads. In addition, material manufacturing flaws, inhomogeneous force transferring circumstances, and seal leak may play an aided role to speed up the bearings failures.

Failure Analysis on Bearings of Railway Freight Cars with Radial Bogie

Causes are investigated on the earlier failures of the bearings for China railway freight cars with radial bogie. Through observing failure objects, checking manufacturing quality, and calculating rolling contact fatigue (RCF) stresses, it reveals that poor manufacturing quality of bearing outer ring plays a key role to the earlier failures and, in addition, mismatch design of RCF stresses between the outer ring and the inner ring acts as an aid actor. Checks verify that surface and core of the outer ring have lower hardness values than requirements; seldom micro-structures, i.e. black-white bands with thickness of around 0.6 to 1.3 mm, appear in the carburized layer of the bearing outer ring; the white part is needle like martensites with higher hardness values, while the black part is pearlites with lower hardness values; and more contingently, crack like manufacturing flaws may appear in the carburized layer with equiaxed grains of ferrites having lower hardness values are around the flaws. RCF values of the outer ring are much larger than that of the inner ring. But the equivalent RCF stress on the present car with radial bogie is lower than that on other cars. This indicates that main cases of the present earlier failures are due the bearings themselves other than the cars.

Virtual Dynamics Simulation on Railway Wheel-Track Contact Force Spectra

A possible virtual dynamics method is developed to replenish the wheel-track contact force histories for assessing properly the vehicles dynamics-fatigue properties under unknown real railway line spectrum. The work starts from known partial on-line inspection data of the force histories and the two known referenced line spectra, i.e. American railway line spectra of grades V and VI. The inspected data are used for selecting a closer line spectrum to real one from the two known spectra, and then, for verifying the developed method. The closer one is determined by comparing the predicted force histories by the two referenced spectra to the inspected data, respectively. The simulation method is gradually developed by adjusting vehicle’s dynamics parameters in terms of a virtual dynamics method to reduce the difference between on-line inspected data and the dynamics simulations. Availability is verified by the method developing process on dynamics simulation of China railway freight car with 23 ton axle weigh.

Mass Customization Marketing Strategies for China Railway Freight Transportation Service

Service marketing theory is used to study mass customization marketing strategy for China railway freighttransport. This research puts forward that, identification and profitability are the requisitions; customizationability of production system, rapid delivery system in between production systems and external organizations,and information support systems are the critical issues to success. With these basis’s, four important aspects areproposed to support mass customization for China railway freight transport: to identify and determine thecustomers who are supplied customized production, to form service differentiation through product designinnovation and service process diversification, to realize railway production intensification, mass production andstandardization operation, to provide quick information for customization marketing with informatizationtochnologies.

Probabilistic Critical Safety Wheel Wear Sizes of Chinese Railway Freight Cars

Critical safety wheel wear size is investigated through considering the fatigue safety effect on RD2 type axle of China railway freight cars. The wheel wear size increase results in a rise of the wheel-rail contact forces, which increase the fatigue stress history of the axle in service. Therefore, the size must be controlled to maintain the axle safety in service before the next overhaul inspection. A field investigation was firstly made on the wear size change regularity. Then, the size related wheel-rail impact forces are solved by a non-linear Hertzian contact theory with a vehicle multi-body dynamic model. In addition, a statistical method is further developed for incorporating the impact forces into the wheelset service load history. Finally, a wear size related critical state equation is established for ensuring the axle safety in service. A stationary solution is statistically obtained for the critical wear sizes with respect to the axle circumferential crack and semi-elliptical crack. It is concluded that the critical safety wear size should be controlled in the range of 100 mm at the statistical level of survival probability 0.99 and confidence 95%.

Probabilistic Critical Fatigue Safety State of the RD2 Type Axle of China Railway Freight Car

Critical fatigue safety state is investigated on RD2 type axle of China railway freight cars. Attention is paid on the grooves near axle boxes, where more fatigue cracks were early appeared even result in at least six derailed accidents. Load history was obtained by vehicle dynamics simulation combining with on-line inspection. Braking loads and effects of maintenance and off-round of wheels are also incorporated. Semi-elliptical and external circumferential cracks are employed for crack growth simulation. Crack shape change and shear stressing of the semi-elliptical crack are taken into account. New crack growth rate modeling in which covers from cracking threshold to toughness related fracture state is applied for residual life evaluation. Critical fatigue safety state is defined as the crack size from which the axle can be safely operated to next overhaul inspection. Critical crack size is estimated step-by-step with the crack shape change. Results show that the external circumferential crack is more dangerous than the semi-elliptical crack. Application more than two years in production verifies that the present assessment is available and reliable.

Fatigue Failures of the 353130B Type Roller Bearings on China Railway Freight Cars

Causes are analyzed to the three shelling failures of railway 353130B type of roller bearings on China 70t grade of freight cars with K5 type of tilting bogie. These bearings are all failed in service lives less than two years, which is quit less than the overhaul inspection interval of 800, 000 km mileage of vehicles and the design life of 2, 000, 000 km mileage. The failures are all originated from the position at the outer ring inboard side nearly to the seal seat. Metallurgical observations reveal that the material chemical composition and microstructures are all in the reasonable range except for the hardness values. This implies that the manufacturing techniques may not match the requirements to lead to the reduction of fatigue strength. Elastic-plastic finite element (EPFE) analysis reveals that the position at the outer ring inboard side nearly to the seal seat is subjected to the maximum equivalent stress amplitude, which well match the situations of failures. In addition, a comparison is made to the bearing on the same axle weight freight cars But K6 type of bogie. Results reveal the maximum stress amplitude for K5 type of bogie is larger than that for K6 type of bogie. This means the bearings failures are relative to the local structures. Therefore, both the manufacturing techniques and the bogie structures should be advanced to improve the bearing service lives.