Kowloon Wharfs-trolley track's multiple turntables

Interesting photo with details about the rails laid on the docks. If you look along the pier from left to right you start with a narrow gauge track and a turntable. About 1½ meters to the right, the next pair of rails with a turntable is visible, and then another rail that is not connected to a turntable. This arrangement of rails is repeated to the right without another turntable.

I'm quite sure that the we see narrow gauge and also standard gauge tracks that share the left rail. The right hand standard gauge track is for the cranes visible in the back, and the one in the middle is for trains to the KCR Terminus.

Initial impressions, perhaps 1930s looking at individuals (supervisory staff ?) dressed in white and wearing topees.

Probably even 1920s, see this one with the same type of letters and number 51 (IDJ's is 52):

Here the two standard gauge tracks are visible, too: one for the crane and the other one for the train. And two extra rails to form narrow gauge tracks (with turntables).

Quick find with the photo ID numbers! The dark vessel with the white stripe in both photos looks similar. Photo taken on the same day?