Crews working atop a highrise building at 33 Tehama Street in San Francisco's South Market neighborhood Wednesday afternoon when supports under a crane used to lift cement failed, compromising an unsecured 2,000-pound concrete wall.
The project developer said in a statement that the 2:45 p.m.&nbsp;incident began when a system used to form concrete walls was being raised from levels 35 to 36 and experienced a partial hydraulic failure.
Fire officials later described the incident as a failure of one of the struts supporting the crane at the building's core elevator shaft, and said the tilt of the crane system caused one of the concrete walls and formwork to lean out.
The initial fear was that the 30-ton concrete pump on the top of the platform would fall off the side of the 35-story building as well as the one-ton concrete slab that stood adjacent to the platform.
The construction company has successfully shored up the wall and forming system for the moment and is working on a permanent fix.