Researchers from Sandia National Laboratories have conducted extensive research on these topics. They have reviewed the current literature, identified knowledge gaps in alternate fuel vehicles and tunnel safety, and developed a generalizable framework to assess tunnel safety for a diverse range of alternate fuel vehicles. Supported by US Department of Energy (DOE) and Federal Highway Administration (FHWA), their research focused on: 

• Reviewing the current research on alternate vehicle type as they relate to hazards in tunnels and identifying knowledge gaps. Their findings are captured in this report 

• Understanding the unique hazards associated different types of vehicles powered by gasoline, diesel, batteries, natural gas, propane, and hydrogen fuel cells

• Developing a computationally inexpensive, adaptable, and generalized framework for assessing safety of alternate fuel vehicles in tunnels 

• The framework incorporates accident scenarios, physics models and consequence models, tank blowdown calculations, parametric sensitivity analysis, studies of tank volume, orifice size, fullness, fuel type, and tunnel geometry characterization with a focus on high-traffic tunnel characteristics. 

Their research was presented at an FHWA webinar on November 9, 2023.  The presentation can be viewed here. The webinar recording is available here and the passcode is mPXM1wk&.