A boat dock structure includes an upper deck, sides extending downward from the upper deck, and a wheel bumper having a substantially round shape. The wheel bumper has a first portion and a second portion, the first portion being positioned under the upper deck, the second portion extending outward from the cutout portion of at least one of the sides to protect the boat dock and a boat from damage when the boat is docking at the boat dock adjacent to the wheel bumper. At least one of the sides may have a cutout portion.