This seems to be the first Ticket to Ride game with Ferries (routes with Locomotive symbols on some spaces) marked on the map but with no mention of Ferries in the rules.
I assume that this was an oversight and that it was intended for the game to use the same Ferry rules as in Ticket to Ride India:
Ferries are special gray routes linking two adjacent cities across a body of water. They are easily identified by the Locomotive icon(s) featured on at least one of the spaces making the route. To claim a Ferry route, a player must play a Locomotive card for each Locomotive symbol on the route, and the usual set of cards of the proper color for the remaining spaces of that Ferry route.
Since the Ferries are always gray in India (as noted) and in Africa, "the proper color" can be any color at all (with locomotives allowed as wild cards for the remaining spaces).
In particular, I assume that the following rule from Nordic Countries does not apply:
Any three cards can be used as a substitute for a Locomotive card.