Special edition paper

Track irregularity is increased by loads of trains and deformation of structures. Since track irregularity affects ride comfort and running safety of trains, we measure track irregularity to align the tracks upon evaluation with appropriate indicators. We call this work track management. In general, the more speed increases, the more track irregularity of longer wavelength affects ride comfort and running safety. With the increase of operational speed by the introduction of new high-speed cars, we accordingly examined whether the present track management indicators could be used for the evaluation of ride quality or new indicators that could represent better the effect of track irregularity of longer wavelength would be required. The running tests of FASTECH360, which is equipped with lateral vibration controllers (active suspension) on bogies, confirmed improvement of ride comfort by more than a few dB compared to an actual train running at 275 km/h (without vibration controllers). Based on those test results, we considered that the present track condition can sufficiently provide good ride comfort in terms of lateral vibration; so, we studied vertical vibration. First, we compared the track irregularity measurement results measured with 40 m-chord, 60 m-chord and 80 m-chord versine methods to the waveforms of vertical vibration acceleration of cars (with and without ride comfort adjustment). Next, we obtained the response of car body vibration acceleration through frequency analysis and compared it to the measured magnification of the present track management indicator. And also, by simulating track maintenance, we compared improvements in ride comfort per track maintenance length. Finally, we carried out actual 40 m-chord track maintenance to understand the improvement in ride comfort. In order to make appropriate track management for ride quality, we have to pay attention to the following. * Relationship between ride quality and vibration acceleration of cars * Relationship between vibration acceleration of cars and track irregularity * Relationship between track irregularity and track management indicator