Looks like a rolling programme. Similar new signs have appeared at Redland and Keynsham.
Good to see the sign at Melksham - from memory there was "always one there" but having gone back though the recent pictures I have that take in the corner, it had been gone a while.
For the record, there remains the double sided road sign pointing to Melksham Station as well, so to some extent the new sign is a duplicate. The big sign across on Station Approach pointing to the Railway Station and Cafe was removed some time between 16th September and 8th December last year (2023)
Edit to add - pictures from 31st March this year, and 16th September and 8th December last year