This article was written in collaboration with WSP Director of Technical Risk Johan Lundin and WSP Associate Director Björn Yndemark. It was first presented as a part of the 8th edition of the International Symposium on Tunnel Safety and Security (ISTSS) in Borås, Sweden.
The transition towards sustainable city planning is challenging from many perspectives, e.g. the speed of development towards fossil free fuels and updating of regulations for controlling risk in the transport infrastructure do not manage to keep an even pace. This applies both at the detailed level regarding technical design requirements and on a more comprehensive performance level of safety objectives that can be verified to confirm compliance with society's safety objectives. This paper presents challenges, experiences and results in connection with the analysis of the risks associated with an underground bus terminal operated with gas-powered buses. A risk analysis approach used in an ongoing project in the final stage of the planning process, which makes it possible to discuss experiences and difficulties based on work in practice. Two main types of injury are studied; fire and explosion, where people can be exposed to both high temperatures, toxic smoke, radiation, pressure waves and impact by flying debris. Fire, may occur with ignition of combustible gas mixture (in air). It can be noted that an underground bus terminal operated by gas powered buses constitutes a complex facility from a risk perspective and that the risk level without special consideration for additional safety measures is expected to be high. Therefore a safety concept is required that is balanced between different types of measures, such as supervision, control and safety enhancing installations as well as inherent passive protection.