From the review:
If you ever wander onto the Ticket to Ride page on the Days of Wonder website, you will see an option to look at fan contributions. You can find over 30 links to maps made by the loyal fans of the game that allow you to play Ticket to Ride in different countries around the world. In 2011, Days of Wonder started to put together map collections that are used with the trains and train cards from either Ticket to Ride USA or Europe. These collections add new mechanics to each map, making them play somewhat differently than the base game. The first three map collections added a dangerous Himalayan route, bonus to destination tickets, and terrain cards that can make routes even more valuable. Today we will be looking at Days of Wonders’ most recent map collection, Vol. 4 Nederland. On this map, players will be claiming routes in the Nederland countryside. Lets get into the review to learn about the new mechanic this brings to Ticket to Ride.