Review to the 22. SAG-Workshop in Bad Vöslau 

On 4th June 2024, the SAG-Baumstatik invited participants for the 22nd time to a workshop, this time on the topic of acoustic tomography. In Bad Vöslau, Austria, 77 participants from various countries met in person and online. The agenda included various specialist presentations as well as a practical session.

The event started with a presentation by Lothar Göcke, who has played a key role in the development of the equipment. Göcke gave the audience an insight into the physical basics of sonic tomography and the functionality of tomogram compilation. Finally, he gave an outlook on which innovations appear worthwhile: On the one hand, this is the use of camera technology and 3D simulators to determine the geometry of trunk cross-sections. Furthermore, current research is investigating how other properties of the sound waves can be recorded and interpreted. This could allow even more precise statements on the condition of trunk cross-sections in future.

In the palace gardens in Bad Vöslau, divided into groups, sonic tomographies were carried out with two different devices on three trees. Participants took the opportunity to literally look over the shoulders of colleagues and exchange practical experience as well as personal tricks of the trade.

In the afternoon, Sämi Prosenz (SV Prosenz & Novak GmbH, Austria) illustrated how sonic tomograms on the same level differ when different measuring positions are selected. Prosenz emphasised that the choice of measurement point position is crucial for a meaningful result. At the end of the workshop, various methods of assessing the safety against rupture of an analysed stem section using an acoustic tomogram were discussed in plenary.

Conclusion of the workshop: an acoustic tomogram is only of limited use without an expert, intensive visual inspection of the tree. Furthermore, an understanding of the underlying physical principles and the algorithms used to generate the images is important for the quality and evaluation of the tomogram. The inclusion of all ascertainable load components in the final safety assessment is also essential for a meaningful result.