You can simply use your browser's web developer tools to see which URL is behind which layer. Most layers are served from a different tile server. Currently these are:

• Standard: tile.openstreetmap.org/
• CyclOSM: tile-cyclosm.openstreetmap.fr/cyclosm/
• Cycle Map: tile.thunderforest.com/cycle/
• Transport Map: tile.thunderforest.com/cycle/
• ÖPNVKarte: tileserver.memomaps.de/tilegen/
• Humanitarian: openstreetmap.fr/hot/

The Tiles wiki page is just an example list of tile servers. It can be edited by anybody, so feel free to add the Transport layer to this list.

You can simply use your browser's web developer tools to see which URL is behind which layer. Most layers are served from a different tile server. Currently these are:

• Standard: tile.openstreetmap.org/
• CyclOSM: tile-cyclosm.openstreetmap.fr/cyclosm/
• Cycle Map: tile.thunderforest.com/cycle/
• Transport Map: tile.thunderforest.com/transport/
• ÖPNVKarte: tileserver.memomaps.de/tilegen/
• Humanitarian: openstreetmap.fr/hot/

The Tiles wiki page is just an example list of tile servers. It can be edited by anybody, so feel free to add the Transport layer to this list.