the kap shui mun bridge is not symmetrical, in that the back span length (two spans) is less than half of the main span length (which would be ). to provide the balance that symmetry will normally provide, part of the bridge has a composite structure. the center of the main span uses a steel-concrete composite to make the structure lighter. the back spans and the rest of the main span are concrete. using the lighter steel cross section in the majority of the main span serves to equalize the horizontal forces on the towers and balance the bridge.