This report includes the Proceedings of the 9th International Symposium on Tunnel Safety and Security (ISTSS) held in Münich, Germany, 11-13th of March, 2020. The Proceedings include 42 papers given by session speakers and 13 extended abstracts presenting posters exhibited at the Symposium. The papers were presented in 12 different sessions. Among them are Keynote sessions, Tunnel Safety Concepts, Fire Dynamics, Risk Analysis 1&2, Tunnel Safety Design Concepts, Poster Corner, Explosion Hazards, Active Protection 1&2, Emergency Management, Ventilation, Passive Protection and Evacuation.  

Each day was opened by invited Keynote Speakers (in total six) addressing broad topics of pressing interest. The Keynote Speakers, selected as leaders in their field, consisted of Anne Lehan, German Highway Research Institute, Germany, Marc Tesson, Centre for Tunnel Studies (CETU), France, Trond H. Hansen, Oslo Fire and Rescue Service, Norway, Mia Kumm, RISE, Sweden, Roland Leucker, Research Association for Tunnels and Transportation Facilities (STUVA), Germany and Rune Brandt, HI Haerter, Switzerland.   We are grateful that the keynote speakers were able to share their knowledge and expertise with the participants of the symposium.