Salesforce Tower is an office skyscraper, the tallest in San Francisco. Located in downtown San Francisco as a key feature of the ‘South of Market’ district, the tower’s glass facades of the tower provide stunning vistas of the city’s skyline and the San Fran bay. In one of the most imaginative and creative uses of any building, the artist Jim Campbell has created the tallest public art piece anywhere in the world: a unique electronic sculpture covering nine-stories at the crown of the tower. San Francisco itself will be the star, with moving images of the city being captured each day and the abstracted images formed into a living collage of videos.
Rather than a single Building Maintenance Unit (BMU) in the centre of the roof, which would not satisfy the requirements for constant upkeep of the glass facade, Manntech designed a complete system with an O-shape track and two twin BMUs. This essentially doubles the cleaning capacity of the system and delivers the required frequency of cleaning cycles.
The BMUs themselves are crane- style machines with an outreach capacity of up to 20 metres provided by telescopic jibs. When not in use, they retract to a minimum of just 8 metres. Not only is does the retracted jib arm provide a compact size when not in use, but the jib on both machines can also be lowered using a parallelogram system, or Z-luffing. This means that in parked position they can be entirely from view.
The distinctive shape of this building tapers inwards towards the roof, which could create a risk that a roof-based BMU comes into contact with and puts pressure on the facade surface as the cradle descends and the building gets progressively wider. To avoid this, the jib arm telescopes out automatically in conjunction with the descending cradle to ensure the load is being taken, as it should be, by the cables and that the system is operating effectively, efficiently and, most importantly, safely. In areas like San Francisco, which are prone to earthquakes, our BMUs are also designed to resist and withstand seismic activity.
Manntech was the natural choice for this facade access solution, having completed many other prestigious projects in San Francisco which are testament to our experience and expertise.