In a deceptively simple operation a “jacking crane” frames part of a tower crane and lifts the crane’s cab and jibs twenty feet, opening a hole for the addition of another 20-foot section to the crane. What’s simple to describe is, of course, the result of technological wizardry and precision skills.
Marie Spear, one of the crane operators at K2 at K Station, a 34-story apartment tower under construction in Chicago’s Fulton River District, describes what’s commonly referred to as a “jump” in the above video.
Five sections were added to the crane last Friday, resulting in a 100-foot jump and bringing its overall height to more than 300 feet. The crane will jump another 80 feet once construction has reached the 26th floor. At that point the crane will carry materials to the building’s full height.
You can see the state of the crane immediately before and after the addition of a section to the tower in the following images.
You can see more video from the K2 construction site at this YouTube playlist.