The Rule of double bridges is a principle of block pushing concerning maximized efficiency of building a double bridge. A double bridge is classified as any two water spaces next to each other being built at the same time. The goal of the rule is to determine when and where the dirt should be removed, and the quickest way to build the bridges. Usually, the rule of double bridges is applied to pools of water such as this, from a level called Rock Pool: The other side of the rule of double bridges is when there is a supply of blocks, and two adjacent bridges of any length, even simply one square: