You may want to consider adding stations (or increasing the number of stations if you have Ticket to Ride: Europe) if you find the board gets too crowded and people are blocked completely from their routes too often (Note: too often. It should be allowed to happen sometimes)
A Train Station allows its owner to
use one, and only one, of the routes
belonging to another player, into (or
out of) that city to help him connect
the cities on his Destination Tickets.
Stations may be built on any
unoccupied city, even if it currently
h> as no claimed routes into it. Two
players may never build a Station in
the same city. Each player may build a
maximum of one Station per turn, and
three Stations throughout the course
of the game. To build his first
Station, a player plays and discards
one Train card from his hand, and
places one of his colored Train
Stations on the chosen city.To build a
second Station, the player must play
and discard a set of two cards of any
one color; and to buil his third, a
set of three Train cards of any one
color. As usual, you can replace any
number of cards by Locomotives. If a
player uses the same Station to help
connect cities on several different
Tickets, he must use the same route
into the city with the Station for all
of those Tickets. The Train Station
owner does not need to decide which
route he will use until the end of the
game. A player is never required to
build any Stations. For each Station a
player has not used, four points are
added to his score at the end of the
game.
Remember that each Station played
allows its owner to use one (and only
one) route belonging to another player
into that City for the purpose of
completing a Destination Ticket. If a
player uses the same Station to help
connect cities on the paths of several
different Destination Tickets, he must
use the same route into or out of the
city with the Station for all Tickets.
