What happens when 3 locomotives are face up in Ticket to Ride?
Discard all 5 face-up cards right away and turn up 5 new ones. This applies any time 3 of the 5 face-up cards are locomotives, during setup or in the middle of the game.
The rule:
In Ticket to Ride, the face-up row always holds 5 train cards, and if 3 of them are locomotives at any time, you discard all 5 right away and turn up 5 new cards.
This happens during setup and during the game, usually right after someone takes a card and the replacement is a locomotive.
If the deck runs out, shuffle the discard pile thoroughly to make a new deck. The rulebook stresses shuffling well, because most discards come in matching sets.
Example:
Ben takes a face-up blue card. The replacement is a locomotive, which makes 3 locomotives in the row. All 5 face-up cards go to the discard pile and 5 new cards are turned up before Ben takes his second card.
Why players argue about it:
Players remember the rule from setup but forget it also applies mid-game, or they only replace the third locomotive instead of all 5 cards.