The top board of the ramps should lay over the top of the vertical member. The wood should be in "shear" , not the bolts holding it together.
It's hard to tell in the picture but I think it's designed that way already. He just has the outer 2 vertical members running past to sandwich everything together. The inner ramps that are supporting the weight are sitting on top of the verticals. But it's hard to be 100% without a better picture.
