IMPACT OF NEW PROPULSION TECHNOLOGIES ON ROAD TUNNEL OPERATIONS AND SAFETY. A PIARC TECHNICAL REPORT (TC 4.4)

Alternative propulsion technologies, including battery-electric vehicles, are becoming more prevalent. Whilst such vehicles remain a small overall proportion of the vehicle fleet, the combination of impacts of Government policy and technological advances in alternative fuels is expected to accelerate their increase in numbers on the road and in tunnels in coming years. There may also be particular initiatives in certain geographical areas, such as on airport land for example, where higher proportions of alternatively fuelled vehicles are seen sooner than on the open road. The introduction of new energy carriers (NEC) vehicles, such as battery electric vehicles and compressed natural gas buses in road tunnels has implications for post-incident recovery, risk analysis, and the definition of new incident types. Vehicle recovery, infrastructure recovery, and the impact on tunnel structure and equipment are some of the specific considerations that need to be taken into account for post-incident recovery. Battery electric vehicles (BEVs) and gas vehicles, including compressed natural gas (CNG), liquefied natural gas (LNG), liquified petroleum gas (LPG), and fuel cell electric vehicles (FCEVs), are the focus of this study. This report provides a summary of the knowledge gained from various investigations into the fire characteristics, firefighting methods, and infrastructure impacts of BEVs and gas vehicles in road tunnels including potential changes in the nature of tunnel safety risks caused by the increasing use of alternative propulsion technologies in vehicles.