This download includes a 4 destination switcher, although can be expanded to add for more than just 4 destinations. This also includes a seamless door, a noob-friendly place (it's impossible to break it or get stuck anywhere,) and the actual railroads for the minecarts. I am not the greatest of builders so forgive me for the bad architecture. Ignore the redstone contraption to the left of the railroad station. Feel free to use this for whatever you need to, although please tell me if you do. You can change it to fit your needs. Ask in the comments if you have any questions or something is not working, I will help. It has fairly complex redstone in it, so be wary.