6. A car body-mounted track inspection device using the inertial mid-chord offset method

  • The RTRI developed an inertial mid-chord offset method track inspection device to be mounted on the underside of commercial vehicle car bodies.
  • A single device can ascertain the 10 m-chord versine waveform (as opposed to the minimum of three devices required in conventional track inspection), making it compact and economical.

The inertial mid-chord offset method track inspection device can detect the waveform of a 10 m-chord versine by processing measured data in addition to using the basic inertial law principle, in which displacement can be obtained through double integration of the acceleration. Since it can output the 10 m-chord versine with a single device (as opposed to the minimum of three devices required in conventional track inspection), the device is compact and can be mounted on commercial vehicles. Accordingly, the cost of its introduction is significantly lower than that of cars used exclusively for track inspection purposes. RTRI previously developed a device to be mounted on a bogie frame, and put it into practical use on the Kyushu Shinkansen. However, as it is sometimes impossible to mount this device due to the bogie structure, a type that could be mounted under the car body floor (Fig. 2) was developed by enlarging the measurement range of the displacement gauge, which was problematic in the case of mounting on car bodies (Fig. 1). This meant the device could be mounted on a wider range of vehicle types, and that a single device could be used for multiple vehicles. Being able to select between two types of device (bogie-mounted and car body-mounted), makes it possible to have an optimum inspection system which takes line conditions into account.

The standard deviation of the results of running tests on commercial lines using this device showed error to be less than 0.5 mm (Fig. 3). High consistency with data from current track inspection cars was also seen, and it was confirmed that the device was capable of carrying out track inspection .

  • fig 1
    Fig. 1 Differences between bogie-mounted and car body-mounted devices
  • fig 2
    Fig. 2 Car body-mounted track inspection device
  • fig 3
    Fig. 3 Results of repeated inspections for the alignment of a 10 m-chord versine in a curved section