3-D Computer Modeling Used to Site & Design New Control Tower at O'Hare

Victoria Soukup Jensen
Published in: 

Kevin Markwell clearly remembers how officials determined the final site for the main air traffic control tower at Chicago's O'Hare International Airport (ORD) in the early 1990s. "Several tower employees went up in a helicopter at the proposed locations and altitudes, sat there and spun the helicopter around in all different directions,"recalls the support manager for tower plans and procedures. "They wanted to see if there were any problem areas for line of sight."

Flash forward 20 years to the siting process for ORD's new South Tower that's currently under construction. Planners performed the same initial legwork to identify site possibilities - examining taxiways/runways and determining functional requirements - but instead of using a helicopter when making the final selection, FAA officials created a virtual 3-D model of ORD and its surrounding environs.


Project: Air Traffic Control Tower Siting & Design

Location: Chicago's O'Hare Int'l Airport

Siting: FAA

Design: exp

Cab Size: 440 sq. ft.

Tower Height: 219 feet (to the top of rooftop antennas)

Construction Start: June 2013

Scheduled Commission: Fall 2015

Of Note: FAA used 3-D model to virtually site the tower, architects used Building Information Modeling software to design it, tower neck is square shaped vs. circular

"The computer lab is much more efficient and does a much better job than the old way," says Markwell. "It offers a 360-degree view from the proposed tower site and lets us see the elevation the tower needs to be to see everything. There are a lot of little adjustments we can make in the lab to be sure we can see what we need to see."

Specialists at the FAA Airport Facilities Terminal Integration Laboratory (AFTIL) constructed the 3-D model at the William J. Hughes Technical Center near Atlantic City, NJ. The model includes all current and proposed buildings, runways, taxiways and other airport features. Using simulation software, FAA officials were then able to digitally view the airport surfaces as if they were in a real control tower.

The virtual siting process typically takes about five months from start to finish, and AFTIL has completed more than 100 control tower evaluations during the past decade.

Crews broke ground for ORD's new tower in June, and the facility is scheduled to be commissioned in fall 2015 with the airport's new south runway, Runway 10R-28L. With five air traffic control stations/positions, the tower will manage all air traffic on the new runway. Both the tower and runway are part of the $6.6 billion O'Hare Modernization Program which was approved by the FAA in 2005.

The South Tower will be ORD's third. The Main Tower opened in 1996 and the North Tower was commissioned in 2008. The South Tower became necessary with the addition of a new 7,500-foot south runway. "We couldn't see about two-thirds of the south runway from the center tower," explains Markwell. "So we knew something had to change, and the only thing available to us was another tower."

A small group of ORD air traffic controllers and supervisors determined what was necessary for the new tower and funneled suggestions to the FAA. About the same time, the City of Chicago provided the FAA with detailed descriptions of the new runway, including elevations and length.

AFTIL specialists then created a virtual 3-D model of the airport, using terrain and building data, aerial photography and information about aircraft and vehicle movement to realistically replicate airport operations, explains an FAA spokesperson.

Markwell's team went to the Hughes Technical Center twice - first to review physical locations and then to review airspace requirements. "Not only did we have to make sure that we could see all of the concrete that we needed to see and all the taxiways, but we also had to make sure we were looking at the airspace that needed to be protected for approaches and departures into and out of the airport," recalls Markwell.

Once the final site was determined and controllers "zoomed in" on the location, they discovered that a small corner of a proposed building was going to make it difficult for controllers to see part of one taxiway. Cooperation between the building owner and city, however, resolved the problem. In the end, the building was modified slightly, and the City of Chicago moved the taxiway 50 feet to make the location work. "It was that kind of work that made it all happen," recalls Markwell. 

The sheer size of the airfield and the large number of buildings, runways, aircraft, vehicles and other objects on it made the ORD tower a demanding project for the technical center team. "The higher number of objects, the slower the computers will update," explains an FAA spokesperson. "Chicago O'Hare is one of the largest and most complex airports in the world, and replicating its surfaces and operations correctly was challenging."

Square vs. Circular

Like the siting team, the design team also used sophisticated computer technology. Architects from the Chicago office of exp used Building Information Modeling software (BIM) to design the new tower.

"Our integration with the engineering side and use of BIM was a critical part of the design process and the design evolution," says Thomas Hoepf, FAIA, vice president/principal design architect at exp. "The modeling of the building and literally every conduit, pipe, duct and piece of equipment in it was done very methodically and in a very integrated and coordinated way."

Hoepf describes the building as a "machine that serves the FAA." He explains that in most buildings, designers specify only general routing of ducts and conduits. "(Exact routing) is usually up to the tradesmen, the installers and the subcontractors. But that coordination often is not adequate for what you need in a building of this nature; and often times, it creates conflicts, depending upon which trade got in first to run their ducts or conduits," elaborates Hoepf. "With BIM software, we can actually show where everything should be located and routed and prescribe that they build it that way."

Initially, the FAA wanted ORD's South Tower to be an adaption of its asymmetric North Tower, but a change in city code required the South Tower to have two exit staircases instead of one. "The minute we added another staircase, we began to think it through differently," recalls Hoepf.

The result is a sleek, symmetrical, square-shaped tower, with the facility's electrical, mechanical and electronic components located just below the cab in the middle of the building. Stairs, elevators and shafts are located along the interior perimeter.

In contrast, most traditional towers are circular, with the elevators and stairwell in the center, and electrical and mechanical components positioned along the interior perimeter walls.

"This simple inversion solved many of the technical challenges of the building type," says exp Project Manager Kristen Armstrong, AIA, LEED AP. "It addresses the primary functional concerns of the mechanical and electrical systems and even more importantly, the electronic components," explains Armstrong. "The project really is about the electronics room that serves the cab."

The new design resolves many of the issues faced by other air traffic control towers, adds Hoepf. "Trying to put all that big clunky rectangular equipment in a room that is shaped like a donut is not very efficient or easy," he explains. "All that stuff has to find its way up the neck into the cab, and there are distances to those cable runs that cannot be exceeded."

ORD's new tower, which will be 219 feet to the top of the roof antennas, will have glass on the two sides with stairwells and concrete on the remaining two sides. The cab floor will be 440 square feet.

Hoepf says he hopes the FAA uses the new design as a prototype for future two-stair control towers. In the meantime, he is pleased with its visual appearance and with what he believes will be improved functionality.

"The shape is very unique in terms of construction," says Hoepf. "The architecture is the structure. It's a very simple scheme, but at the same time, it gave us and the city a design and appearance that is just different than other towers. Aesthetically, we think it is iconic and unique to Chicago."

Chicago Department of Aviation (CDA) Commissioner Rosemarie S. Andolino cites cooperation between the city and FAA as a key factor in the project. "The success of the O'Hare Modernization Program and the outstanding progress we have made on this historic project are due in large part to the great working relationship we have with the FAA," she says. "The collaborative process between the CDA and FAA on the design of the South Air Traffic Control Tower promises to yield fantastic results when the tower is commissioned at O'Hare International Airport in 2015."


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