The second of the three major bridges for the East London Line extension is being moved into place this Sunday and Monday. It's the GE19 bridge that crosses the Great Eastern Main Line (the line out of Liverpool Street), right next to where Shoreditch tube station was. See my map of the whole area.
This photo was sent to me by TfL's actually-being-helpful press office, which shows just about everything, taken from above Brick Lane looking east:
The building on the right is Shoreditch station, and the bridge is sitting where the platform cutting used to be.
The accompanying info says the best place to view the move is Allen Gardens (a short walk from Whitechapel station). Regarding when to go:
The best times to see the bridge actually moving are expected to be Sunday 04:00 to 07:00, 09:00 to 12:00 and 17:00 to 22:00 or Monday 04:00 to 08:00, but are of course subject to progress on site and weather.The bridge will be moved using "strand jacking", which is where a hydrualic ram is used to pull on a steel cable. Once the ram is fully extended, it's disconnected from the cable, retracted, and reattached further down the cable, so the process can begin again.
They say the structure to be moved weighs 1800 tonnes including "kentledge", which is your new word for the day.