A drilling machine working near an underground line connecting Istanbul's central Mecidiyekoy district to the city's main airport accidentally bored through the ceiling of the metro tunnel and the rails, a video shared by Sozcu TV broadcaster showed on Saturday. The video showed the drilling machine in operation and the damage it had done to the tunnel and the rails, Reuters reported. The drill pierced through ceiling of the tunnel and went all the way down to the rails of the metro tracks, it showed.