It is a train bridge - the old North London Line to Broad Street, which will be reused when the East London Line is (eventually) extended.
Inspector Sands
Paul Clarke's weblog - I live in A small town. Wed to Clare and father to 2, I'm a full-stack web engineer, + I do javascript / nodejs, some ruby, python, php ect ect. I like pubbing, running, eating, home automation and other diy stuff, history, genealogy, Television, squirrels, pirates, lego, and time travel.