[djcapelis]

Yep yep. Just sayin', that's what else they'd be. :)

That said, for 250km/h and up, electric is pretty much standard for rolling stock. It's a bit less common to have the freight going through the same infrastructure be all mandated to be electric too though.

(Also now that I look more into it, it's unclear that it's mandated that the trains that go through the tunnel be electric. In fact, Swiss Railways just bought some new rolling stock for maintenance that's hybrid electric/diesel (uses electric only when overhead power works, diesel otherwise) which makes sense for maintenance, but likely means the tunnel is perfectly equipped to deal with diesel emissions from trains. In addition, before they completed the overhead work, in 2014 they announced that diesel trains could transit the tunnel. Not open publicly, but that the capability existed. Anyway. Interesting question whether they actually require all rolling stock transiting the tunnel to be electric, and if so, why. I'm guessing it just currently happens that all the scheduled trains traversing the tunnel are electric, so the poster said "all electric".)