This photo is from the Flickr Group "I love Grain Elevators", which often involves a nearby railroad.

Brant Alberta. by Bernard Spragg. NZ, on Flickr

What is the function of having that tracked excavator up on the platform above the tracks?

Note that there is also an auger alongside the tracks that presumably is capable of loading and possibly unloading granular material like grains and pelletized fertilizer from hopper cars.

I've often seen setups like this for unloading gondolas.... Lycoming Valley empties stone gondolas like this, and Ohio Central does two unit trains of coal for a power plant daily this way.

OK, somebody has to ask. Might as well be me.

How did they get it up there? That would take an impressive crane. Piece-by-piece?

First time I saw a backhoe climb up on top of a railroad hopper by using the excavator bucket I couldn't believe it, but this goes way above that....

I wonder if it climbed on top of a railcar, and then climbed from the railcar to that structure?

Amazingly enough, Google Street View took a drive down the gravel road through Brant, AB. The resolution isn't quite high enough to tell what kind of attachment is on the end of that machine's boom, but it does not look like a excavating or clamshell bucket (it's too small).

Maybe the attachment is a plate compactor or a vibration head, being used to shake each car during loading (consolidating the load) and/or unloading (to get it all out?)