An incredibly staged photo.
A truck was parked on the tracks, the tram was photogenically positioned and the staff was also neatly spread out and not allowed to move too much, or the photo will be blurred.
The tram is empty and perhaps the route was also closed that day.
The officers in charge were clearly posing in the background. A signalman demonstrates in the background how to operate the mobile signal.
So they thought of everything: even the date of the shooting (Thursday, 30 July 1931) was painted on two wooden boards and can be seen in the foreground.
A picture with a lot of directives, but fortunately also a lot of details.