Development of an inertial track geometry measuring trolley and utilization of its highprecision data

In 2015, a truly lightweight track geometry measuring trolley was successfully developed to enable real-time measurement after all track maintenance work. A commercial product model named the LRS100 was realized that is small (disassembled total length of 1,600 mm maximum) and lightweight (13.4 kg, which is about one-third that of the track geometry measuring trolley the LIGHTREC). Seven items may be measured in real-time: track gauge, cross level, alignment (right and left), longitudinal level (right and left), and twist. The measuring accuracy is high, and it far outperforms current track geometry measuring trolleys in terms of repeatability error. The mechanism of the LR-S100 is very simple and easy to maintain because there are no moving parts for measuring alignment and longitudinal level. These advantages, which are not found in any similar conventional product, were achieved with a brand-new track geometry measuring principle called the ‘differential-difference method’ for the LR-S100. Since the measurement accuracy of the LR-S100 is high, it is also possible to restore the actual track geometry and to compensate for errors in gauge and cross-level irregularities by means of a three-wheel trolley without any additional sensors.