Platform structure over a live railway line

A reinforced concrete deck being tied out and cast beside working railway tracks, with the overhead electrification masts and contact wire in the frame. The reinforcement is laid in bands over shuttered panels, with starter bars left standing for the columns that carry the next level.

Two things govern a pour like this. The first is the line: the deck edge sits close enough to the track that reinforcement lengths, crane slew and even where a man may stand are all set by the railway, not by the programme. The second is continuity, because a deck cast in pieces across separate possessions still has to behave as one slab, so construction joints are placed where the design says and not where the day ends.

Column footings and pedestals for the same works were cast first in open cut, with the reinforcement cages set and the pedestals brought up to a common level before the frame above was started.