Due to environmental considerations, much current transportation policy development is aimed at increasing usage of renewable energy sources. These include gaseous fuels such as LPG, methane, and hydrogen, along with electricity. This research project focused on a literature review that was intended to research the risks involved in using alternative fuels in road tunnels and underground garages. Gaseous fuels and electric vehicles pose new risks that we, due to our greater familiarity with liquid fuels, are unused to. The greatest of these relate to gaseous fuels and pressure-vessel explosions, and the release of toxic gases such as hydrogen fluoride from Li-ion batteries undergoing thermal runaway. Two workshops were organised to obtain feedback from stakeholders and initiate discussion regarding the issue. Future research, risk-reducing measures, rescue service guidance, and changes to regulations and guidelines are discussed and proposed in this report.



The purpose at the outset of the creation of this report was to review and update current knowledge about alternative fuels for vehicles in relation to their use in tunnels and garages. A secondary purpose was to present scholarship, knowledge, and statistics regarding incidents involving vehicles that use alternative fuels.Important fire- and explosion-related issues that relate to alternative fuels have been surveyed. Areas in which further investigation or the development of new tools for the prevention and handling of fire scenarios are required are described. The overall goal has been to present information that can guide government authorities and the transportation sector in dealing with these risks in future garages and tunnel systems.

Current regulations and practice for the construction of tunnels and garages have also been investigated. Rescue service guidelines for extinguishing fires in vehicles that are powered by alternative fuels have been examined in detail. The study was limited to those alternative fuels that are used commercially in Sweden, i.e. for which there is at least one filling station open to the public. In addition, at least one of two conditions had to be met; the fuel should behave differently from conventional ones, or there should exist uncertainties regarding the risk of fire or explosion posed by it.