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A Multisensor Platform for Kinematic Track Surveying Thomas Wildi

The increasing use of modern high-speed trains requires increasing safety standards and, consequently, accurate railway tracks. Traditional methods for track surveying do not any longer satisfy economic aspects. For these reasons, HTA Burgdorf developed a track surveying platform in co-operation with terra vermessungen AG, Switzerland. The project is financed by KTI (Commission for Technology and Innovation by the Federal Office for Professional Education and Technology). The system features the modular structure and the capability of kinematic surveying. For various surveying tasks (track surveys, deformation measurements, staking out of railway lines, tunnel profile measurements) the platform can be flexibly adapted. The platform is designed as a lightweight construction (operation weight: 45 kg) and can be easily handled by two operators. It contains sensors such as two inclinometers (super-elevation and gradient), a track gauge meter and two odometers. For the trajectory survey, a GPS-RTK or an autotracking tacheometer can be used, alternatively. With a post processing software, track geometry parameters such as inclination (super-elevation and gradient), height differences, twist, track gauge and the trajectory (horizontal / vertical) can be computed. The Institute of Geodesy and Photogrammetry together with Grunder Ingenieure AG carried out first tests using the platform combined with GPS-RTK. An 18 km long railway line was surveyed. The forth and back track allowed a comparison of the observed trajectories. In sections without GPS obstructions, an accuracy of 1.5 cm was obtained for the horizontal component. The vertical component was worse by a factor of 1.5. A system is being developed for staking out slab tracks. A remote-controlled tacheometer tracks the survey platform where the super-elevation and the track gauge are monitored. Corrections to the nominal track layout are displayed and can be used for staking out.