The Sandridge rail trail is a shared use path that connects Station Pier in Port Melbourne and City Road, just south of the CBD. It's a pleasant and convenient route, but it falls short of being a high quality off-road route.
Interactive map is here.
This path is well used by people cycling and walking.
Shared path. When I rode this path on a sunny morning it was well used by cyclists and people walking, particularly older people. Shared paths are not ideal. People walking dislike cyclists riding past at moderate cycling speeds (20km/hr), while enforcing a "code of conduct" for pedestrians (e.g requiring that they stay left at all times, avoid walking in groups, and strictly controlling small children and dogs) destroys the pleasure of the walk. On the other hand, requiring cyclists to ride at slow speeds while passing pedestrians decreases the utility of this as a transport route. The best practice here would be to create separate paths for walking and cycling, where space allows.
Path loses priority at Bridge St.
No crossing at Bridge St. This needs either a zebra crossing (raised) or a signalised crossing with bike/pedestrian priority. At the very least, it should have a "keep clear" zone to prevent vehicles from blocking the route while queuing (the gates of the tram crossing are just to the left of the view above).
I'm not sure what works are being done here at Ingles St-- hopefully a better crossing!
Rails blocking the path. At the tram depot, the path is blocked by yellow rails that are supposed to force cyclists to give way to trams leaving the depot. These rails slow cyclists down and are extremely difficult (if not impossible) for people towing trailers, or riding long wheelbase bikes, or riding trikes. A better solution would be to have gates that close when trams approach, leaving the path unimpeded at all other times.
At the first tram depot crossing.
At the second depot crossing. This gentleman told me that he'd recently slipped and fell on the tram tracks.
Poor connection to the city. The trail just ends at City Road, with no clear safe connection across the river to the CBD.
Almost at the city, but not quite!
Addendum November 2020: a cargo bike in difficulties at the chicane.