Complex sentence: The turbine/whirlpool interchange requires fewer levels than stack interchange while retaining semi-directional ramps throughout and has the left-turning ramps sweep around the center of the interchange in a spiral pattern, although with slightly less capacity because the ramps turn and change height more quickly.
Split into simpler sentences: The turbine/whirlpool requires fewer levels while retaining semi-directional ramps throughout and has the left-turning ramps sweep around the center of the interchange in a spiral pattern. This has slightly less capacity because the ramps turn and change height more quickly.