• RecallMadness@lemmy.nz
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      4 months ago

      I doubt it’s /just/ smoke ventilation. Sure, it’s primarily there for fire safety.

      But it probably provides ambient ventilation for the tunnel too. Tunnels with trains get hot. Most things, living or inanimate don’t like heat.

      And if it’s always ventilating, it’s also might be expelling brake and metal dust from passing trains.

      But all speculation. I’m not a train engineer, so I’m probably wrong.