Re: Dartford Crossing
My wifes' dad (who died in 1977 so I never knew him) was the British Rail structural engineer responsible for all the bridges, viaducts and stations from Exeter to the Penzance. One of his responsibilities was the Tamar rail bridge which needed repainting every year or so. He used to do random inspections in the works while painting was being done (to ensure that the workmen were not just painting over the rust but were actually cleaning off the rust *before* painting) and sometimes took my wife with him (she was 10-12 at the time). She distinctly remembers walking through the tubes on the top of the railway bridge..
So that bridge is forever known in our house as "Dads' bridge".
Me - you'd need to knock me out and carry me up there. I'm really, really not a fan of heights. Although I don't mind flying (and the couple of flights in a light aircraft where I've had a go at flying were great fun).
 He was, originally, a stonemason by trade. He orginally worked in his fathers' granite quarry in Cornwall then ended up working for the railways/
 Our bed is made out of reclaimed timbers from Dawlish station - they were replacing one of the platforms and he managed to scavenge the usable parts (light oak) and had a carpenter freind of his make it. It's held together by cast-iron angle-brackets and 1" coachbolts. He thoroughly believed in overengineering.. The bed is really, really heavy - 4" solid oak beams are *not* light.
 Well - originally made for my wifes' half-sister (who is 18 years older than her). Her marriage fell apart just before we got married so she was quite happy for us to have the bed. Fortunately, you can take it apart (although the hand-cut oak struts that go from the side beams to the centre beam are all numbered because they only really fit on one place. Unfortunately, each side has numbering starting from 1 so we had to add L or R to denote which side it went)