The Tilt of San Francisco’s Millennium Tower has Deepened as Engineers Work to Reverse Lean

Despite the best efforts of architects, San Francisco’s iconic Millennium Tower continues to experience a deepening tilt and sinking motion towards the west.
Recent monitoring data, reviewed by NBC Bay Area’s Investigative Unit, reveals that the tower is leaning over 29 inches at the corner of Fremont and Mission streets, exceeding the previously disclosed measurement by half an inch.

Engineers had undertaken excavation work beneath the sinking condominium earlier this year to provide additional support to the tower, which was constructed on a former landfill. However, this effort seems to have resulted in a further tilt towards the west.

The data, derived from rooftop-based measurements and foundation-based determinations, indicates an almost one-inch shift to the west compared to the tower’s initial tilt before the north side was reinforced with six concrete-filled steel piles.

While engineers initially used the rooftop data as evidence of progress during the project’s first phase, they now question its reliability, attributing potential variations to weather conditions. They argue that foundation-based data is more dependable.

According to this foundation-based information, the tower’s westward tilt has increased by about a quarter-inch, which project engineer Ron Hamburger describes as “negligible.”

Hamburger expressed confidence that once the remaining design load is transferred to the piles, there will be no further movement of the roof towards the west. The next step for Hamburger and his team is to secure the foundation to the twelve piles driven along Fremont Street. These piles, with a diameter of 24 inches and driven 270 feet into bedrock, are designed to support an impressive 1 million pounds of weight.

The engineers are hopeful that by the end of the month, they will be able to reverse the tower’s tilt, which was initially disclosed to residents in 2016. Their goal is to stabilize the structure and restore its vertical alignment, ensuring the safety and integrity of the Millennium Tower for years to come.

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