Hydrogen Powered Vehicles in a Tunnel Incident – Risks and Consequences

The mobility sector is subject to a massive transition from fossil fuels to new energy carriers. The driving force is the reduction of greenhouse gas emissions in order to minimize the impact on global climate. Hydrogen represents a promising fuel as it can be used in combination with internal combustion engines as well as fuel cells. However, due to its physical and chemical properties it potentially poses high risks in an incident scenario. This mainly refers to its wide flammability limits as well as the common way of storage at nominal pressures of 350 bar (busses and trucks) and 700 bar (passenger cars). This paper presents the findings of the Austrian research project “HyTRA” that aimed at an evaluation of potential hazards in tunnel incident scenarios involving hydrogen powered vehicles. Five scenarios with a high potential risk have been identified and investigated related to the consequences for tunnel users and the tunnel facility. Ultimately, a comparison to incident events with conventional vehicles gives information about the consequences for the level of tunnel safety.