Melbourne

I think it would interfere too much with the regular network to do loading and unloading on busy in-service tracks.

I feel it's easy to dismiss prematurely.

• Unloading could done outside of peak traffic times (as is done now with trucks as far as I can tell).
• Dedicated staff on both the tram and on the street could speed up the process significantly, especially if unloading is limited to a few specific sites.
• Batching of goods could go a long way toward limiting the number of unloading points.
• And as you say, "Sidings", if available for both loading and unloading, which is more feasible once cars are off the relevant streets, basically prevents a lot of interference with ordinary passenger trams.

It'd also be interesting to think about this as a distributed system, where many of the passenger trams have portions of their space dedicated to freight storage such that the load of carrying freight is much more smoothly spread out over the network.