Chicago— Like a runway from the heart of Chicago's Millennium Park, spanning 620 feet across Monroe Street to the third-floor level of the Art Institute's new under-construction Modern Wing, a sleek pedestrian bridge is rising. Drawing visitors from the park to the museum will be the new Nichols Bridgeway, a slender blade of a bridge just 15 feet wide. Its curved white-painted underside resembles the hull of a boat or a racing shell. The floors will feature textured aluminum planking.
Both the Modern Wing and the Bridgeway are anticipated to open in spring 2009.
Setting the bridge on course required precise planning to accommodate the tight site in a congested area downtown. Planning for the bridge construction began in summer 2007, with groundbreaking following in September. Danny's Construction Co. Inc. (DCCI), Gary, IN, the steel erector, hired Central Contractors Service Inc., Chicago — a member of the ALL Erection & Crane Rental Corp. Family of Companies — to supply cranes for the project.
The Monroe Street/Art Institute section of the Bridgeway is composed of four curved-bottom structural steel sections. The four sections were planned to be prefabricated into maximum lengths and weights that could be erected utilizing Central's fleet of equipment. The sections, each with an average weight of 100,000 pounds and approximately 65 feet long, were to be welded together as each was lifted.
A 550-ton Grove GMK 7550 hydraulic all-terrain crane from Central hoisted the estimated 200 tons of steel sections. A 40-ton Demag AC40 hydraulic all-terrain was used to assemble the GMK 7550 and also served as an assist crane to move shoring towers for the bridge.
"The site is particularly tight and required exact dimensional layouts to allow for erection of the bridge elements," said Rich Linsenmann of DCCI. "Many times the clearances between the building, the crane and the bridge were within 1 foot. Central met the challenges as we expected they would."
John Martello, Central Contractors Service general manager, said, "Setting these heavy steel segments across Monroe Street, on a rising plane ending 60 feet in the air at the entrance to the museum addition, was a challenging undertaking because of the tight clearances. The crane had to be positioned as close as possible to the bridge to achieve the desired operating radius of 79 feet."