This raw, mute footage documents second city civil engineers constructing a new bridge for road traffic over New Street's tangled railway intersections. A no-music, no-narrative film might be a tough watch for all but the keenest industrial film enthusiasts, but there's something mesmerising about watching construction on this scale and in such detail. And attention is richly rewarded with some arresting images: labourers heaving and wrenching girders; molten rivets hammered into place.
The film came into the BFI National Archive's collection via British Transport Films, who probably acquired it when the railways were nationalised in 1948 and the various rail companies' film units either shut down or merged. It's likely that it was never shown publicly in this form but was raw footage intended for use in another film.