In Trafffic, you want to be the first player to get rid of all your cards. To discard a card, you need to find or create a group of three cars positioned in the same pattern on the game board as is shown on your card.
Everyone plays simultaneously. To move a car on the board, take the green light from another player, then move a car of your choice one space in the desired direction. (If you hold the green light, you must wait for another player to take the light and move a car before you can make another move.)
As soon as you spot a matching combination, say "Beep! Beep!", then show your card to other players so that they can verify that you're correct. If you goofed, the player who spots the error gives you a card from her hand as punishment for you and a bonus for her. When one player runs out of cards, the game ends; anyone with cards still in hand receives penalty points equal to the number of cards they hold. The player with the lowest score after three rounds wins the game.
The cards with green backgrounds show more complicated traffic patterns and can be used to handicap experienced players. You can also give them to the player with the lowest score after rounds one and two to give the other players a better chance against this movement maven.