The railway bridge over Deptford Creek had to be lifted to allow masted vessels to pass. Any failure on the part of the railway, or its staff, to raise the bridge in a prompt and timely manner was a criminal offence. (The offence was abolished in the 1980s.)
The bridge in the photograph was replaced by a lift bridge that simply raised the central span vertically above mast height.
Curiously the 'Ha'Penny Hatch' footbridge is missing from the photograph. As can be seen the railway bridge only occupies part of the supporting stone bases and the footbridge should be seen on the side viewed. It may be that the footbridge was replaced in 1913 and this photograph taken between demolition and rebuilding, or it may be that the photograph actually dates from the mid 1930s (when the Southern Railway demolished and did not replace the footbridge) or after.