DNA: Where is biggest problem in Uttarkashi Tunnel rescue operation?

Uttarkashi Tunnel Collapse Update: 40 people have been trapped in the tunnel for about 150 hours. Rescue operation is more than half completed. Now there is hope of the workers coming out safely in the next few hours. These pipes of 3 feet diameter are proving to be a lifesaver in taking 40 people out of the tunnel, because it is through these pipes that the workers will be taken out of the tunnel. Therefore, these pipes are being laid in the debris affected area.