Impact of new energy carriers on tunnel design and safety: Status report of PIARC TC 4.4 WG4

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.
As a result of these changes, the nature of tunnel safety risk (including from fire) is expected to change with time, and detailed consideration of the risk of significant incidents involving such vehicles is required. This should include the evaluation of incident consequences with particular attention paid to fire characteristics and toxic emissions and their impact on tunnel users and on emergency intervention strategies.
PIARC technical committee TC4.4 initiated working group WG4 in order to investigate this issue within the PIARC working cycle 2020 -2023.
There are too few recorded examples of incidents involving vehicles with new propulsion technologies, commonly called new energy carriers (NEC), to be able to make statistically relevant statements about the effects on the tunnel design and infrastructure. It is also currently not possible to derive specific instructions from experience gained from incidents of such vehicles. Hence, PIARC TC4.4 WG4 collates currently available information on ongoing or recently finished research programmes and highlights their most important elements so far. WG4 consists of approximately 30 members from 16 different countries around the world.
A first report concerning the status of ongoing research in the topic of NEC vehicles has already been published by PIARC. The paper presented here expands on the previous work and describes the work done within the working group to date.