When attached to a cart using the Cart Assembler, the Bridge Builder will enable a cart to traverse gaps by building a one block wide bridge in front of itself that a Railer or Large Railer can place tracks on. This can be used to prevent a Railer cart from having to hug the level of the natural landscape, and can also be used to provide a consistently level path when used with a Height Controller. The only materials it can use for building bridges are Stone, Stone Bricks, Wooden Planks, and Bricks.
Will build bridges when an attached Railer needs them using provided Stone, Stone Bricks, Wooden Planks, or Bricks.