thatmarkguy wrote:
Your final score is the sum total of the values of your train legs (1 for a 1-car connection between any two cities, 2 for a 2-car connection, 4 for a 3, 7 for a 4, etc), PLUS the number on all the Tickets for which you successfully completed a network linking the named cities, MINUS the numbers on all the tickets whose cities you did not join in your network. PLUS the longest-route bonus if you had the longest continuous route.
And to expand on Mark's answer, the connections are scored as they are actually completed. Then at game end, points are added for each ticket completed and having the longest train, and subtracted for tickets not completed.
It may not seem like there's a difference beetween a running score or scoring all at the end, but the running score gives players a rough idea who is leading at any one point, and thus can influnce decisions on track-laying.