The square shaft form - a departure from traditional shaft/bulb-top towers - evolved in response to two challenges: Chicago’s classification as a high-rise requiring dual stairs (previous towers had one); and FAA’s need for direct/minimal pathways/distances in routing cabling/electrical/mechanical from Junction Level into the Cab above.
The solution inverts conventional solid-core tower plans, pushing “core” elements to the perimeter, thereby opening the center for feeds directly up to the cab. The shaft provided an economical, non-combustible structure utilizing standard formwork for fast construction. The concrete edge is expressed as a “ribbon” framing glass-clad stairs and visually ties the Tower, Base Building and Ground Plane.
The Base Building is organized in two parallel bars - one housing MEP to the north to buffer taxiways; the "people" bar, located to the south to maximize daylight/views, and present a friendly face to employees and visitors.
There are no extraneous elements - everything is integrated. The result is a simple, elegant tower that speaks to the efficiency of the FAA’s operations, the importance of O’Hare as a world-class airport and the reputation of Chicago as a hub of exceptional architecture.
The project began with the directive to site-adapt the FAA's standard control tower prototype. This alternative design evolved out of an iterative process with architects, engineers and controllers focused on providing flexibility and adaptability to integrate new systems as technology advances. The FAA considers this tower a significant advancement that now serves as the new precedent for the design of future towers.