A large, shared network of railroad tracks develops across the continent. But it can be annoying sometimes if other players blatantly exploit your own routes. So, from time to time you need to put a stop to that.
Vexation, included in the Immortal Eyes Edition, provides each player with three personal track sections. These individual tracks (in six different colors) allow each individual player to establish their own route connecting two adjoining cities. Any player wishing to use the cities connected by a colored track segment must establish a separate link around the other players track. No more than two colored tracks may adjoin the same junction and colored tracks may not be replaced by black ones.