IMU-based orientation transfer at Semmering base tunnel: Another proof of IMU-based orientation transfer practicability

Back in 2005, first experiments at the Sedrun attack of Gotthard base tunnel showed the applicability of autocollimation and IMU units to contribute as an independent measurement technique for orientation transfer down to deep shafts. Since then, evaluation strategies have been refined and in 2017 another project at the Semmering base tunnel was started to confirm the method. The paper at hand explains the base setup of the sensors, the compensation strategies and evaluation steps and gives the results of the project measurements compared to the gyroscope measurements performed at the same time. It is shown that the overall orientation is within the expected accuracy range and its quality is comparable to the gyroscope results, so the IMU orientation transfer method has proved reliable again.