Side saddle traversable drilling rig

A system comprising:

• a wellsite, the wellsite comprising a row of left well cellars and a row of right well cellars;
• a land-based drilling rig comprising:
• a drill rig floor, the drill rig floor having a V-door, the V-door defining a V-door side of the drill rig floor;
• a subfloor, the subfloor supporting the drill rig floor, the subfloor comprising beams;
• a leftmost substructure box and a rightmost substructure box, the substructure boxes supporting the subfloor, each substructure box including a lower substructure box and two upper substructure boxes, wherein there is a gap between the two upper substructure boxes, the leftmost substructure box positioned to the left of a left cellar and the rightmost substructure box positioned to the right of the right cellar, the rows of well cellars perpendicular to the beams and wherein the lower substructure box is a rectangular prism extending the length of the subfloor with the long side parallel to the V-door side of the drill rig floor;
• and
• a mast, the mast mechanically coupled to the drill rig floor, the mast having an open side and having a V-door side where the V-door side of the mast faces the V-door side of the drill rig floor, wherein the drill rig floor is movable relative to the subfloor for positioning of the mast above one of the well cellars.