The Gotthard-Basetunnel in Switzerland with it's total length of 57 km is going to be the longest basetunnel of the world. The bearing for the tunnel driving is determined by the high-precision surveying gyroscope Gyromat 2000. Due to the effect of small errors of bearing for tunnels of this length, the determination of the bearing has to be accomplished with extraordinary diligence. At the intermediate tunnel Sedrun the propagation of the bearing from aboveground to underground is extremly difficult because of the complex locality. Therefore the Alp Transit Gotthard AG charged the Chair of Geodetic Metrology and Engineering Geodesy of the Swiss Federal Institute of Technology, Zurich (geomETH), to independently verify previous measurements. Together with the Chair of Geodesy of the Technische Universität München a kinematic propagation of the bearing was developed, set up and carried out in the shaft of Sedrun, by coupling inertial measurement with autocollimation. This paper discusses possibilities to minimize the influence of errors of inertial navigation by a novel observing operation in two faces. Inertial measurement with its error models are presented. The advantages of autocollimation in this context are characterised. As conclusion the accieved accuracy is compared to conventional measurements. Two campaigns have been carried out in the shaft of Sedrun. GeomETH was responsible for the connection to the local net of the Konsortium Vermessungsingenieure Gotthard-Basistunnels. The concept to propagate the bearing including the measurements with the inertial navigation system was realized in the range of this thesis. As an approvement of the propagation of the bearing measured by high-precision surveying gyroscopes, the combination of inertial measurement and autocollimation proved of value. Due to the different technology, an independent reliable comparative measurement to the propagation of the bearing by the surveying gyroscope Gyromat 2000 was introduced.
«
The Gotthard-Basetunnel in Switzerland with it's total length of 57 km is going to be the longest basetunnel of the world. The bearing for the tunnel driving is determined by the high-precision surveying gyroscope Gyromat 2000. Due to the effect of small errors of bearing for tunnels of this length, the determination of the bearing has to be accomplished with extraordinary diligence. At the intermediate tunnel Sedrun the propagation of the bearing from aboveground to underground is extremly diff...
»