As if the inexplicable loss of energy wasn't bad enough, they weren't the only ones suffering from this issue. Even the train was suffering from the energy drain.
The lamps in the carriages went out immediately they entered the tunnel. This absence of light from artificial sources and the absence of light from the sun in the tunnels plunged the whole place into utter darkness.
The train's engine also suffered a drain on its energy reserves. The heat of the fire in its furnace and the heat of its boiler both took a heavy hit and dipped. This slowed down the train and put it at risk of stalling.
The train couldn't be allowed to stall, or they would be at the mercy of the world barrier. So a special fuel was poured into the furnace.
This special fuel caused the fire in the furnace to explode and soar. The heat rose quickly, and the boiler resumed working at full capacity. This caused the train to resume its normal speed out of the tunnel.
