Risk Assessment of Hydrogen Fuel Cell Electric Vehicles in Tunnels


The need to understand the risks and implications of traffic incidents involving hydrogen fuel cell electric vehicles in tunnels is increasing in importance with higher numbers of these vehicles being deployed. A risk analysis was performed to capture potential scenarios that could occur in the event of a crash and provide a quantitative calculation for the probability of each scenario occurring, with a qualitative categorization of possible consequences. The risk analysis was structured using an event sequence diagram with probability distributions on each event in the tree and random sampling was used to estimate resulting probability distributions for each end-state scenario. The most likely consequence of a crash is no additional hazard from the hydrogen fuel (98.1–99.9% probability) beyond the existing hazards in a vehicle crash, although some factors need additional data and study to validate. These scenarios include minor crashes with no release or ignition of hydrogen. When the hydrogen does ignite, it is most likely a jet flame from the pressure relief device release due to a hydrocarbon fire (0.03–1.8% probability). This work represents a detailed assessment of the state-of-knowledge of the likelihood associated with various vehicle crash scenarios. This is used in an event sequence framework with uncertainty propagation to estimate uncertainty around the probability of each scenario occurring.

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This work was supported by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen, Fuel Cells and Infrastructure Technologies Program. The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the U.S. Government. The authors wish to thank Paul LaFleur of the Federal Highway Safety Administration for his help in identifying vehicle crash data. The authors also wish to thank Joe Rigney of the Massachusetts Department of Transportation for his help in providing tunnel information and feedback on the analysis. Finally, the authors with to thank Will James and Laura Hill of FCTO for their leadership in this analysis, as well as Jay Keller (consultant), Nick Barilo (Pacific Northwest National Laboratory), and Carl Rivkin (National Renewable Energy Laboratory) who provided very useful feedback on the analysis and report. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

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Correspondence to Chris B. LaFleur.

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Ehrhart, B.D., Brooks, D.M., Muna, A.B. et al. Risk Assessment of Hydrogen Fuel Cell Electric Vehicles in Tunnels. Fire Technol 56, 891–912 (2020). https://doi.org/10.1007/s10694-019-00910-z

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  • Hydrogen
  • Risk
  • Fuel cell electric vehicle
  • Event sequence diagram