Physical description
Colour photocopy of photograph, two images on page. Top image, on bottom 'View of tray in Portal' shows mining equipment with tray fully extended in portal entry. Sign fixed to RH side of portal: ' Stop if red light is on'. Bottom image, across image on bottom ' View looking out of portal' shows mining machine tipped on side, obstructing portal. Machine has name 'Bell' on front.
Presumably, the tray has been up when the machine has attempted to enter the portal and 'flipped' the machine over.