Not surprised this ended up with a ban.
I'm typing this whilst sitting in an open field. No farm animals and the few trees a decent distance away in case there is any lightning. Think I sould be safe as the rabbits seem to be ignoring me too..
For anyone actually interested in the tunnel it was surveyed professionally a few years ago. It was constructed in several phases due to the expansion of waste tipping which eventyually covered the track route.
Far better structural condition than many structures that 28DL members visit and the overall view on the past two GAT surveys was that it is well preserved. I've not seen any significant evidence of recent movement.
For anyone else thinking of doing some 'volunteer' surveying: a bank card (don't vary in size like pencils!) or even a dedicated scale/colour card is more use than a pencil for scale
A few grammes of plastic I always carry - only a couple of quid expense (bearing in mind the small plastic cards are thick enough to scrape light ice of the car window, open a yale lock etc so muti-purpose tools!)
Though I don't carry ranging poles when out for a walk I do generally have a foldable 2m ruler (sneaked into the odd post on here I think)