In yet another rail top shot, Ashish stands in the light patch from the newly discovered vent hole in the 25C. He tries (unsuccessfully) to get a GPS fix through the hole to log the coordinates that would prove useful during the next Tunnel top trip. The circular object on the tunnel roof in the distance is the end of one of the six axial Jet Fans. These are located of the tunnel roof for moving stagnant air when required. This picture represents the truer colours inside the tunnel 25C- the orange patches are caused by the Sodium Vapour lamps located at regular interval.