After the Tohoku-Pacific Ocean earthquake, saving energy became a central concern for all Japanese railway operating companies, since Japan lost a major source of electric power supply. It follows therefore that R&D at RTRI should focus on power supply technologies. At the same time, for the first half of the 21st Century, Japan will face falling birthrates, an aging society, and a shrinking population, resulting in a rapid decrease of the working population. Consequently, maintenance-free technology is another key subject for RTRI. This paper describes the recent work on power supply technologies.
This paper outlines the recent research and development of train control systems, solutions for existing signaling equipment problems and the application of radio communication technology to railways. It describes what has been called the "intelligent train" and a train control system for secondary lines which does not require interlocking devices in stations. It also describes solutions for point machines on secondary lines, lightning-inducted voltage in cables and a visibility test for obstruction warning signals. Finally, it describes the application of millimeter wave technology which enables high speed and large capacity communications.
Railway Dynamics is the research field for finding out technical solutions for dynamic problems caused by the characteristics of the railway system. RTRI has been tackling many problems in the field of railway dynamics. To accelerate this research and development, RTRI has been developing organized simulation tools in the form of a "Railway Simulator" using high performance computing technologies, since 2010. This simulator mainly focuses on interaction in boundary regions such as wheel/rail/track/structure, pantograph/catenary, and so on. This paper describes current research activities including the development of the railway simulator for the purpose of achieving a safer and more reliable railway system.
Ground faults from positive conductors on fixed structures with relatively high ground resistance are a persistent problem in DC feeding systems. Such faults are difficult to detect because of the weakness of the fault current. In turn, if these faults continue for several seconds, they can lead to broken overhead contact lines, feeder wires or masts. A new system was therefore devised to detect ground faults using a protective wire and ‘protection devices.' This paper presents the system outline and the results of several indoor and on-site experiments on the proposed system.
Prevention of accident occurring at the contact area between overhead contact lines and pantograph requires careful maintenance of overhead contact lines, resulting in high maintenance costs. Current on-board overhead contact line monitoring systems mainly check the dynamic geometry of contact wires. However, their static geometry is also extremely important for efficient maintenance work. This paper therefore presents the development of two methods which estimate static height of contact wires using contact force and pantograph height. This paper describes the new methods in detail and shows some simulation and experimental results.
A contactless measuring method was developed to measure static positions of overhead contact lines from vehicles, using stereo image measurement and laser distance measurement. Measurement experiments were conducted. By using the combination of two types of sensors, this method can make high detection performance and high measurement accuracy compatible. Moreover, since it is completely contactless, measurement of wires not in contact with the pantograph, such as the catenary wire and the auxiliary catenary wire, is also possible. This method automates the measurement and quantification of condition diagnosis of long contact lines, and should increase maintenance efficiency.
This paper describes the development of a method to evaluate the performance of communication networks, in order to improve the efficiency of their design for radio-based train control systems. This method makes it possible to estimate the possible influence on operations of a new communication system, while avoiding the time and cost of conducting tests on actual lines. So the system development size and cost for not only a design stage, but also a prototype and an experiment can be reduced. In this paper, the author presents an outline of the performance evaluation system, and show examples of performance evaluation of a communication network.
In order to apply satellite positioning to train control, an algorithm for positioning was developed with a one-dimensional constraint condition using line coordinate data and multipath error reduction using the given value, different physical phenomena, and satellite redundancy. The positioning performance was evaluated using the positioning satellite observational data acquired on operating lines, confirming that large errors were reduced and that there fewer drops in the positioning rate quality. The algorithm was then transferred to the embedded system and confirmation was obtained that 10 Hz real-time positioning could be performed.
This paper presents a method which makes use of data collected in the monitoring devices fitted to electric point machines. First, a model was built to detect the lock position of the point machine. Then, an algorithm was devices to predict variations in the lock position, by employing meteorological data, air temperature and humidity. A study was then conducted to investigate how the predicted lock position data could be utilized. Second, we have proposed how to provide supporting information for planning the work of the lock position adjustment. Finally, a method was developed to enable visualization of the predicted position data.
A series of experiments on the wheel/rail traction coefficient were carried out with a twin disc rolling contact machine by varying the surface roughness and the temperature of the wheel and rail discs, and using sprayed water, for the purpose of obtaining fundamental knowledge about how to prevent wheels slipping during driving and wheel sliding during braking. The results showed that the maximum traction coefficient value occurred in the range of 1 to 3 μm of the combined roughness under any temperature conditions, and its value increased to 0.4 with increases in temperature.
The authors have been studying a method for evaluating rock slope stability by applying a non-contact vibration measurement technique. Consideration of the size of the rock block, its shape and conditions supporting it are indispensable for improving the accuracy of the evaluation method. Accordingly, an aerial survey system to observe the shape of the rock block was built. Next, software was developed to automatically generate a three dimensional finite element analysis model from the data collected relating to the shape of the block. Finally, a rockfall risk evaluation technique was proposed using the parametrical analysis results of the FE analysis model regarding loads exerted on and conditions supporting the block.
This study investigates the effects of track rolling vibrations on the running safety of railway vehicles. During earthquakes, viaducts are subject to rolling vibrations in addition to lateral and vertical directions, causing tracks on viaducts also to vibrate in the rolling direction. A vehicle dynamics simulator (VDS) was modified to enable simulation of rolling vibrations on a track. Sinusoidal oscillation analysis showed that running safety decreased as the ratio of the roll amplitude to the lateral amplitude of the track increased. In addition, it was verified that the decrease in running safety due to the rolling vibration of the track on rigid-frame viaducts was smaller than for pier type viaducts. This is because rolling vibrations on rigid-frame viaducts are smaller than on pier type viaducts.