If you are in London, free and bored on Tuesday (or maybe you just need to get between Ealing Broadway and Wandsworth Road) there is apparently a : s1kr1t rail-replacement bus that runs at 9.45am
each Tuesday. It runs empty all the time because they didn't tell anyone about it.
If only it were a Saturday. I'm just not quite geeky enough to take a Tuesday off work specifically to do that, though.
I draw the line at going along specifically to examine new bits of railway infastructure when I happen to be open (talking of which, there is a rumour that the Woolwich Arsenal DLR extension opens on the 10th!)