These are Clan specific Cross-Junctions that perform a very special action. At the start of the game, each player takes their matching Clan Tile, and when a T-Junction is upgraded to a Cross-Junction, players may use their tile instead of a regular Cross-Junction. The benefit? That player can immediately place a Minecart on the square facing any direction they desire with a speed die of 1! Cool eh?
Think of the tile as a target, and your goblin Minecart is being catapulted over the edge from the surface into the Mine below! Sure, it gets another 'cart into the mix quickly, but probably makes quite a mess of the paintwork in the process!
The tile and ability can only be used once and only if that player does not have both Minecarts on the board already.
Oh, and done even think about picking up Jewels on the square you land in -they are crushed and should be placed back in the bag!
Finally, the tiles may not be placed during the Chasm phase (Goblins are crazy, but not THAT crazy) so be sure to use it before the Chasm Card is revealed!