In Japan, a majority of steel bars are welded by the gas pressure welding because it is superior to other joining methods in workability.
In the Hyogoken-Nanbu earthquake on January 17, 1995, a number of gas pressure welds in reinforced concrete members were fractured at the weld interface. Since then, a reliable quality inspection method has strongly been demanded.
A method of "flash removal by hot shearing," which makes it possible to easily inspect the weld immediately after welding, has been recently developed. This method is effective in evaluating gas pressure welds in real time, and it possesses high workability and high reliability.
The reliability of inspection method, such as penetrant test, ultrasonic test and flash removal by hot shearing method, was verified by tensile and bending tests of welded joints. After that, the relation between the inspection results and the destructive test results was investigated. As a result, it was clear that flash removal by hot shearing method has the highest reliability. Thus, flash removal by hot shearing method is superior to penetrant testing and ultrasonic testing as a quality inspection method for gas pressure welds.

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The Maglev system employs a linear synchronous motor (LSM) with the primary side on the ground, and uses a combined levitation-guidance system and double-layered propulsion coils. To analyze electric surge propagation, we measured the surge propagation between propulsion coils. We also set up simulation models and simulated the surge propagation by using the Electro-Magnetic Transients Program (EMTP). It was found that the measured values agreed well with the values simulated by EMTP. Therefore, it was verified that the proposed surge propagation models for simulation were very useful to estimate the surge propagation of coils used for Maglev.

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Solidification processes, which are used to produce rare-earth (RE)-Ba-Cu-O high critical temperature, Tc superconductors, are effective to obtain a high critical current density, Jc at 77 K, and are very promising for high field applications as a superconducting quasi-permanent bulk magnet, flywheels, magnetic shielding, current leads and levitation systems with liquid nitrogen refrigeration. Isothermal undercooling solidification in air with oxygen annealing and Nd123/MgO thin film cold seeding technique were applied to textured Ag-doped Y-Ba-Cu-O superconducting bulks to seek high-efficiency of process, homogeneity of composition and feasibility of batch production. A large single domain, 38 mm × 38 mm in size, was exemplified. The result implies that the melt-process to which the isothermal method and thin film seeding are applied in the Y system fits the production of larger bulks for large-scale applications.

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Millimeter-waves are attractive as a broad-band transmission technology. In this paper, we discuss the millimeter-wave storage transmission system technology as a means of millimeter-wave broadband mobile communications in railways. First, we grasp the performance required for the millimeter-wave storage transmission equipment, sort the measurement results of the performance in railways, and exemplify the transmission system when used for track measurement. Second, we introduce the structure of millimeter-wave storage transmission equipment, and estimate the performance of the manufactured equipment to prove that it satisfies the required performance. Finally, we explain future subjects for the millimeter-wave data transmission of railway track measurement systems.

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Mutagenic effects of static and time-varying (50 Hz) magnetic fields (MFs) were investigated using bacteria, yeast and fruit fly. Exposure to a 5-Tesla static MF caused an increase in the gene conversion frequency in yeast and an increase in the somatic recombination in fruit fly while the frequency of point mutation was not affected in yeast, fruit fly or bacteria. When exposed to a 50 Hz, 40 mT MF, the point mutation frequency in bacteria was not affected. Point mutation and gene conversion frequency in yeast was also not affected by exposure to a 50 Hz MF of 30 mT. On the other hand, somatic recombination was significantly increased by exposure to a 20 mT field in fruit fly. These results show that the mechanisms of mutagenicity of static and 50 Hz field are different. Whenever mutagenic effects which can cause cancer were detected by our test systems, the degree of the effects is very small though we use field strength which is 1,000-10,000 times greater than the ones to which we are actually exposed to. This suggests that the possible carcinogenic effect of MFs are practically negligible for the majority of human beings.

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Evaluation of environmental safety is very important for human health. It is known that railways provide a clean transportation system with low CO₂ emission, but there is little information about the evaluation of ecotoxicological safety in the railway transportation system. In this paper, we report about ecotoxicological safety tests and the bioremediation research for PCB contaminated ballast stones. The former is an introduction of biological methods used in our laboratory to evaluate the environmental safety that can be applied to railway environments. The latter is an example of bioremediation research using a PCB degrading microorganism. Since there are no good physico-chemical methods to remove PCB contamination from ballast stones, bioremediation might lead us to a solution for environmental safety.

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The aim of this study was to evaluate the toxic effect of heavy metals to bacteria and plant. A spiderwort (Tradescantis clone BNL 4430) and coliform bacteria (Esherichea coli strain MV1184 and Comamonas testosteroni strain TK102) were used in this study. The growth of C. testosteroni strain TK102 was inhibited by copper, lead, and cadmium. Cadmium shows the strongest growth inhibition among these three metals. In an assay of Tradescantis, zinc reduced the amount of chlorophiles in leaves. Copper inhibited flowering and had a fatal effect on Tradescantia.

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The Environmental Engineering division, RTRI is responsible for the estimation and evaluation of environmental safety of newly developed systems such as Magnetically Levitated Trains (MAGLEV). Not only the well-known "traditional" environmental effects of railroad systems such as noise and vibration, possible adverse effects on human health are also studied. Among them, the cancer-causing activity of electromagnetic fields used to lift and propel MAGLEV trains has most intensively been studied. Efforts are also made to eliminate the negative legacy left by past technology. This includes the biological degradation of polychlorinated biphenyl (PCB). In this paper, I review the biological studies that have been performed and are being performed at RTRI.

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