Level 10 Construction announced February 4 that it has begun to erect the five-story basement on 181 Fremont Street, signaling the construction start of Phase II on the project, which is located in the South of Market (SOMA) neighborhood of San Francisco. To help achieve this technically challenging phase, the company has brought in a massive Wolffkran 700 B Luffing tower crane, the first of its kind used in the US.
The Wolff 700 B crane is known for its ability to move extremely heavy loads at quick line speeds within a tight urban footprint. The crane will remain on site for about a year.
The $540 million 181 Fremont project is an 802-ft-tall, 70-story luxury residential and office tower that will truly transform the city's skyline. Designed by Heller Manus Architects and developed by Jay Paul Company, the tower is adjacent to the new Transbay Transit Center and features a state-of-the-art exoskeleton designed in a saw tooth pattern, with a magnificent spire that will ascend from the crown of the building.
The pre-certified LEED platinum project includes 435,000 sq-ft of Class A office space, as well as 67 luxury condos on the top 17 floors.
Construction crews have completed deep excavation, shoring and other foundation elements necessary for site preparation. Level 10 has installed a 60-ft-deep base slab to prepare for building out the basement, which is scheduled for completion in three months. Phase III of construction will include going vertical with the structural steel erection of the building. Construction of 181 Fremont is scheduled to be completed in the second quarter of 2016.
Steve DeWees, project executive and manager of Level 10’s San Francisco office, said in a recent news release that the tight construction site, which shares a shoring wall with the Transbay Transit Center (TTC), needed a crane that could maneuver easily in a compressed footprint.
“This Luffing tower crane is one of the only cranes made today that has the capacity needed for the size of steel that will be used in the construction of this building,” he said. “We have heavy steel box columns on six corners of the building, and each segment is five inches thick. They are welded to a box and erected one to two floors at a time. Most cranes in the U.S. don’t have the capacity to pick that weight out at the furthest points.”
A Luffing tower crane is a specialty crane that maintains the hook at the same level while the jib moves up and down. The Wolffkran 700 B Luffing tower crane incorporates the latest in crane technology and operator aids, allowing for safer and more efficient construction. It can move over 40,000 pounds in a load with a line speed of 623 ft per minute and has a tower height of 1,000 fet. The crane is manufactured by Wolffkran AG, Germany and is distributed in the U.S. by Maxim Crane Works, L.P.
Last June, the project used some of the deepest caisson's ever drilled on a San Francisco building. Plunging an average of 262 ft into the ground, the 44 caisson shafts measure five to six ft in diameter and were drilled at such depth because 181 Fremont sits on landfill where the San Francisco Bay used to encroach.