Framing this enclosure are 17 large steel beams that were trucked into the north Loop on Sunday morning on two big rig trucks. From there, they took a helicopter to the roof of theWit.

For three hours, the Sikorksy S-58T, owned by Midwest Helicopter Airways of Willowbrook, Illinois, punctuated the normal calm of a cold, cloudy Sunday morning. Jim Triggs piloted the twin-turbine helicopter in from the west along the main branch of the Chicago River, did a slow turn east of State Street, then settled over the intersection of State Street and Wacker Drive.

The S-58T can lift up to 4,500 pounds and fly as fast as 125 miles per hour. Midwest has owned it since the 1980s. In 2010, the helicopter delivered camera gear to the roof of 35 East Wacker Drive during filming of Transformers 3. (Left) Triggs from a 2011 video by Chuck Derer.

One steel beam at a time was attached to either a 100-foot or 300-foot cable, depending on where the load was going, then carried by the helicopter to the other side of the Unitrin Building, to the roof of the 27-story hotel, where a crew from McHugh Construction Company was waiting to secure the beam in its proper place. Often the helicopter backed into position.

“All the credit goes to my roof crew and ground crew,” said Triggs on Monday. Helping him were two signalmen on the ground, Paul Snyder and John Amador, who also got each load ready. A spotter on top of the Unitrin Building, Jeff Stonebrook, made sure Triggs stayed clear of nearby buildings. Joe Rukavina spotted from the roof of theWit. The closest the helicopter got to a building, says Triggs, was 20 feet.

“Without the radio men, it would be an impossible task to complete the job. When we had only 20 feet to the building, I just rely on their words to keep me clear.”

At Marina City, people watching the spectacle, which started at 9 a.m, lined the south edge of the plaza level. One of the spectators was Scott Greenberg, president of ECD Company, owner of theWit. To people in the crowd, he seemed to know a lot about the lift and when someone unknowingly asked what his connection was to the project, Greenberg said he was “just one of the workers.”

The work was slowed by light winds that gently rocked the helicopter, making it more of a challenge to lower the beams to very precise spots for crews on the roof to nudge into place.

Greenberg watched the lift nervously from the balcony of a south-facing unit at Marina City but at one point, he went inside, saying, “I got to sit down. I can’t take it anymore.” (Right) Greenberg checks his shot of the helicopter in lower right frame from a balcony on the 51st floor of the west tower.

Although most of the lifts took no more than five minutes, one in particular required Triggs to hover for 25 minutes. After that, the Sikorsky, burning 110 gallons of jet fuel per hour, went back for refueling. When it returned, the wind was a little calmer and the sun even came out occasionally. Wacker Drive was closed to traffic from Dearborn Street east to Wabash Avenue. State Street was closed between the bridge and Lake Street. Greenberg says the new ROOF should be ready during the first week in May. (Left) The Sikorksy S-58T picks up the last beam from the first of two trucks. (Below) More images. At bottom, the helicopter rises to the level of the sign on the 41-story (commercial size) Unitrin Building. 35 East Wacker Drive is at left.