A wind turbine rotor blade and a wind turbine incorporating the rotor blade include a first and second composite skin. A first and a second spar pultrusion having a base and a plurality of integral ribs generally normal to the base are attached to the inside surface of the first and second composite skins and extend the span of the rotor blade. At least one shear web connects a rib of the first spar pultrusion to a corresponding rib of the second spar pultrusion. The width of the spar pultrusions decreases in a step-wise fashion along the span of the rotor blade from the root to the tip. The leading or trailing edge of the rotor blade may be selectably opened for inspection and repair.