Bay Area/ San Francisco/ Transportation & Infrastructure
Published on November 18, 2019
No, Sutro Tower is not brokenPhoto: Razmig H./Hoodline Tipline

Hoodline tipster Razmig H. alerted us last weekend that 46-year-old Sutro Tower appears to be missing a mast, a sudden change which was also discussed on Reddit and Twitter over the last few days.

The Sutro Tower website confirms one of the three masts atop the tower is currently undergoing replacement, in order to add several new broadcast antennas "as part of the Bay Area’s portion of the nationwide broadcast spectrum repack program". The initiative will make additional frequencies available to broadband users, making room for the rollout of 5G technologies.

According to Planning Department documents, the repacking project will add seven new broadcast antennas, replace four existing broadcast antennas with new antennas, and remove four existing antennas.

Work is expected to take until December. The Federal Communications Commission (FCC) has scheduled testing of the new antennas for January, with a go-live date sometime next March, according to the Sutro Tower website.

The new stacked antenna array. | Photo: Courtesy of Dielectric

Antennas and other needed equipment come from broadcast manufacturer Dielectric.

"This is one of our most complex repack antenna designs, in large part due to the strict earthquake code that applies to antennas installed in the San Francisco Bay Area,” said Keith Pelletier, vice president and general manager of Dielectric in a statement earlier this year.

In order to meet the earthquake code, the stacked array will be reinforced with guy wires which will be anchored at the top of the platforms.

"These design considerations called for a grade of steel that is much thicker and stronger than that which is customary for antenna construction," Pelletier said in the statement.

View of the tower before (left) and after (right) construction. | IMAGE: Via SF Planning Department

Construction also included the temporary removal of the tower’s characteristic cladding on all three legs beginning approximately 550 feet above grade.

Following the installation of strengthening components on the tower structure, the cladding panels will be reinstalled.

Once complete, Sutro Tower will return to the same familiar appearance San Franciscans are used to.

Thanks to tipster Razmig H.! Have you seen something interesting while you’re out and about? Text Hoodline and we’ll try to find out what's going on: 415-200-3233.