DAX to count number of distinct values in one column for paired value permutations in other column

[hp0655]

This one's hard to describe, so better to show.

If I have the example data below, how can I create a table that tallies the number of common trip_ids for a pair of stations? In real-world terms, I want to count the number of trains (each has a unique trip_id) that serves a pair of stations.

My desired matrix and/or flat table would look like this (though it would be ok to have the identical pairs (e.g., CUS-CUS) also included, if that's easier:

Note that the separate stop_id_1 and stop_id_2 don't exist in the dataset - I assume I'd need to define them somehow in the calculated table.

Would much appreciate any help here! This is beyond my expertise.

[lbendlin]

Please provide sample data in usable format (not as a picture - maybe insert into a table?) .