What are these barcodes stuck the pillars holding up a bridge for an elevated train used for and how are they used? This is the DLR in London.
A: It’s a level you target with a fancy theodolight, what each bar does is that it represents numbers which the theodolight scans accurately and then works out the meters above sea level height. I’m guessing your near Crossrail so it’s probably there to monitor if the pile drops in height as they dig under it.