The famous Sears Tower in Chicago, IL will be getting more than a name change this year. Engineers have created a “skydeck” on the 103rd-floor of the famous building. Visitors will be able get a view of not just the city skyline, but down below as well. The glass box will extend almost 4.5 feet from the actual tower allowing visitors to appreciate the height of the famous structure.

Each “ledge,” measuring 12 ft long and 10 ft tall with floor space of about 4.5 ft by 10.5 ft, fits between existing columns. Structural frames, strategically hidden behind ceiling and drywall, support the boxes, which are being hung from cantilevered steel frames with no structural elements other than fastening clips, “resulting in an unimpeded view of the city of Chicago and the street below your feet,” says Terry McDonnell, principal at Halcrow Yolles, project engineer.

San Francisco based firm, Environmental Design Services, offered their engineering services to improve the quality of the skydeck. Since the skydeck will be very high and risk more exposure to weather implications, air diffusers are directed toward the glass boxes to increase airflow and decrease condensation. Heat elements were also added to prevent ice from forming on the roof, and ramps were built to create access for those who are in wheelchairs.

Engineers have worked diligently to ensure that this structure is not only impressive, but safe as well. A series of tests were done on a mock model of the skydeck, which included adding 2 1/2 times the alloted code for pedestrian loads. All sides of the glass box also have redundant laminate to ensure safety. After testing, it was concluded that each skydeck will be able to hold 5,000 lbs and withstand wind pressures of 125 lb per sq ft. Construction on the skydeck began in January of 2009 and should be completed by June 2009.