result.transitResults, on desktop and mobile, with no flag and at no extra cost. transitResults is omitted when the SERP has no transit block.
Values are text as Google shows them, in the language of the SERP (06:29, 5:10 am, 2h 15m, 0 changes, Ohne Umsteigen). Google uses the same block for trains and buses, and the result does not say which.
departures holds every departure the page has, in page order: the ones it shows, and the ones it shows only after a click (“N earlier trains”, “More options”, a closed booking site), with expanded: false.
Layouts
Google shows the block in four layouts, and each returns the fields it shows. Each example below is the result for the page in its screenshot, shortened with// ….
Route block
On a train or bus query: a route form (origin, destination, date), a summary (fastest, cheapest, dailyDepartures) and the departures. departures has every departure of the day: the 3 the block shows, the earlier train and the ones under “More options”, with expanded: false.

Route block in Google Search
train tickets london to manchester in the United Kingdom, on desktop:
Short block
On some flight queries: atitle (“Consider taking the train”) and the departures. A departure without a fare on the page (”—”) has no price.

Short block on a flight query in Google Search
flights london to paris in the United Kingdom:
EU route unit
In the EU, a list of booking sites (Google, Trainline, Trip.com, …), each with its own summary and departures. The departures of every site come in one list, each with itssupplier, as in the EU places unit: the site’s fastest and cheapest are in supplier. The transport websites next to the unit (the operators of the route) come as websites. No origin or destination.

EU route unit in Google Search: Google open, the other booking sites collapsed
train paris lyon in France: Google’s 3 departures, open on the page, then those of the 6 other booking sites, 21 in all.
EU schedule
In the EU, a summary and the departures, without a route form or booking sites. Google shows the route and the date in one line of text under the title (“De Paris (Toutes les stations) à Nantes · sam. 24 oct.”), which is not returned: noorigin, destination or date.

EU schedule in Google Search
paris nantes en train in France:
Transit results structure
All fields are included only when Google shows them.Departure
position, departureTime, arrivalTime and expanded are always present.