So far, I found:
English
- https://masto.canadiancivil.com/@reece, Reece Martin from RMTransit
- https://mastodon.social/@OhTheUrbanity, OhTheUrbanity
- https://social.notjustbikes.com/@notjustbikes, NotJustBikes
- https://mstdn.social/@nerd4cities, Ray Delahanty AKA CityNerd
- https://urbanists.video/ in general seems to be a PeerTube instance that focuses on transits
German
- https://zug.network/@bahnnews_austria, BahnNews Austria
- https://mastodon.social/@derloris, derloris
- https://wien.rocks/@vcoe_mobilitaet_mit_zukunft, VCÖ
These are in German but you didn’t limit your question to ones posting in English:
Noted, I intentionally didn’t limit it to English, it would be good to see non-English speaking part of fediverse after all