A video of the first sg fruitee ex Wakefields Merbein is seen climbing up grade out of Amphitheatre.Listen to the dipped welds in that. 80lb rail on concrete will not last with surface quality like that.
Good observation, skitz, I heard the same in Greensleeves, clip and equired, but he said it was an axle counter, on the track just near his position, for recording.
So you reckon it's the welding, that is creating the clunck, clunck, sound. Do the welds need more grinding, although without being on site, it's hard to say.
Greensleeves, may be able to give some inside, info, seeing he's, been on location.