On UCSF’s Parnassus campus, the 1250 B US luffing cranes do almost all the lifting, from 32-tonne columns to a mobile crane lowered into the basement
How do you build a 15-storey hospital when the operating rooms and emergency department next door never close, the site has one access road and there is no room for mobile cranes? At the University of California San Francisco, the answer is two of the largest tower cranes on the US market.
Two WOLFF 1250 B US luffing cranes are building the new UCSF Health Helen Diller Hospital in the Parnassus Heights neighbourhood, alongside the existing hospital. It is the first time two 1250 B US cranes have worked together on a US jobsite, and only five of the model are currently operating in the United States.
A site tougher than downtown
The triangular plot sits between the existing hospital, residential streets and a forested area, with a single road in and out. “There is very little space available for logistics and material handling,” said Drew Szabat, construction manager for the project. “The construction site conditions here are significantly more challenging than on those projects in downtown San Francisco.”
So the cranes, erected in spring 2025, were placed along the edge of the site rather than in the middle. Their 65 m jibs still cover most of the work area, and they can stay in place for the whole project, including interior fit-out after the structure is complete.
Tall, slim and on special foundations
The 1250 B US has a maximum capacity of 40 t in two-fall operation and 19.7 t at the jib tip. Despite a tower footprint of only 3.3 by 3.3 m, both cranes stand freestanding at around 79 and 85 m, reaching about 152 m with the jib raised.
Conventional crane foundations were ruled out by California’s seismic rules, the campus geology and nearby utilities and foundations. Instead, the cranes stand on engineered bases of pipe piles and steel grillages.
The site’s only transport system
With no space for other lifting equipment, the two cranes move almost everything: rebar, structural steel and steel box columns weighing around 32 t each. For the columns, the cranes sometimes work in tandem to raise them from horizontal to vertical. Because there was no room for a ramp to the basement, the tower cranes even lowered a mobile crane of about 38 t into it.
All of this happens next to patient care areas, including operating theatres and the emergency department. Site preparation started in 2022, disruptive phases were planned years ahead with hospital departments, and noise, dust, vibration and exhaust were tightly controlled. Over existing hospital buildings, the cranes may only swing with an empty hook.
“The ongoing hospital operations, combined with the geological challenges and the extremely limited logistical possibilities that San Francisco presents, meant that the two WOLFF 1250 B US cranes were the only machines that could meet the requirements of our project,” Szabat said.
One crane will take down the other
The end of the job is just as unusual. One WOLFF crane will dismantle the other, common practice elsewhere but rare in California, where the procedure had to be planned and approved by Cal/OSHA three years before the first crane went up. It will be only the second time in San Francisco that one tower crane has dismantled another.
The second crane will then be climbed down to about half its height and removed by a 600 t mobile crane working from several positions, because the adjacent road serves emergency vehicles and cannot be closed. Preparation alone takes about a year. Dismantling is planned for early 2029, with the roughly US$4.3 billion hospital due for completion in 2030.
For WOLFF, the project reflects a broader shift. “Construction projects are becoming larger, heavier, and more logistically demanding, increasingly requiring the capabilities of high-performance cranes in the largest capacity class,” said Michael Herget, president of Wolffkran Inc.
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