The new, taller structure would not only have to be made lighter, but would need to resist higher wind loads and utilize existing foundations which had been constructed prior to the project delay. The project’s structural engineer, Leslie E. Robertson Associates, arrived at an innovative structural solution, which abandoned the original concrete frame structure in favor of a diagonal-braced frame with outrigger trusses coupled to the columns of the mega-structure. This enabled the weight of the building to be reduced by more than 10%, consequently reducing the use of materials and resulting in a more transparent structure in visual and conceptual harmony with the tower’s elegant form.