Files (stored at Wikimedia commons
http://commons.wikimedia.org/wiki/File:3-11-portal_superstructure_1.JPG - 1.9MB
http://commons.wikimedia.org/wiki/File:3-11-portal_superstructure_2.JPG - 1.9MB
http://commons.wikimedia.org/wiki/File:3-11-portal_panorama.tif - 11.6MB
Not entirely happy with the sharpness of these pictures, but after three attempts that came out worse I've decided the hell with it.
This thing looks like it's about the same length as they give for the tunnelling machine, so possibly it's something to do with getting the machine ready. The yellow crane was there before this was built and I think is over the actual portal face - it can't move any further to the left because it is too low.