Two independent reports by Statens vegvesen (The Norwegian Public Roads Administration) conclude that the use of battery-electric machines in tunnels presents as little or less risk of fire as conventional machines.

To read the news is in Norwegian:

https://www.bygg.no/na-ser-vegvesenet-mulighet-for-a-stille-krav-til-batterielektriske-maskiner-i-tunnel/1546348!/