In the past 10-15 years comprehensive risk models have been established as a common and efficient tool to systematically investigate the influence of hazards on tunnel safety and to quantify and assess their effects in terms of risk. These models investigate the potentially hazardous phenomena and their complex interaction effects in a tunnel on a scientific basis. These proven methods are applicable to also investigate and quantify the influence of new hazards, if complemented by suitable additional modules. In the course of the envisaged decarbonisation of the transportation sector, fossil fuels in future will be more and more replaced by climate-friendly alternative propulsion energy carriers,thus also bringing potentially new hazard scenarios into tunnels.