Of Material Interest Elegant Steel and Aluminum Pedestrian Bridge Links to its Art Institute

imilar to a racing shell and its crew cutting through calm morning water, the new Nichols Bridgeway cuts through the airspace between Chicago’s and the new Modern Wing of the Art SInstitute of Chicago. Resembling the hull of a racing shell, the slender blade of a bridge is just 15 feet wide and spans 620 feet as it rises from the Great Lawn in the park and crosses Monroe Street to the third floor of the Institute.

The steel bridge will feature textured aluminum plank floors, steel railings with stainless steel mesh sidings, and will offer walkers impressive views of Millennium Park, Michigan Avenue, and the lakefront. Both the museum addition and the bridge were designed by architect Renzo Piano and, as symbiotic works of art in themselves, are striking additions to the cityscape.

The Monroe Street/Art Institute section of the Bridgeway is composed of four curved-bottom structural steel sections. The four sections were prefabricated into the maximum lengths and weights that could be erected utilizing the contractor’s fleet of equipment. The steel segments, each with an average weight of 100,000 lbs. and approximately 65 ft. long, were welded together as they were lifted and set across Monroe Street, on a rising plane ending 60 feet in the air at the entrance to the museum addition.

Setting the bridge on course required precise planning to accommodate the tight site in a congested downtown area. Because the clearances between the building, the crane, and the bridge often were within 1 foot, exact dimensional layouts were required. The contractor, Central Contractors Service, used CAD project drawings and 3-D lift simulation software to ensure proper crane choice, efficiency, safety, and minimal cost.

The Modern Wing addition incorporates cutting-edge green technologies including a large sunshade of extruded aluminum blades, popularly referred to as the “flying carpet”, that will capture the north light and deliver it to the third-floor gallery skylights while gently shading the rooftop garden.

Planning for the bridge construction began in summer 2007, with groundbreaking following in September. Both the Modern Wing and the Nichols Bridgeway are expected to open in spring 2009.

For more project information, visit www.artic.edu. For more crane contractor information, visit http://www.centralcrane.com.

Nichols Bridgeway (day) Courtesy of the ADVANCED MATERIALS & PROCESSES/OCTOBER 2008 5