16th Street BART plaza closed, blasted clean with glass

On Monday, the plaza at 16th Street BART station was given one of the most graphically thorough cleanings imaginable, ahead of an extended 11-day partial closure that will leave the famously busy and grungy transit hub easier to clean in the future.

BART circulated footage of cleaning crews in full body suits and masks power washing the plaza tiles. Via the BART blog, the transit agency identified the substance used as a combination of high-pressure water and ground glass.

The station and plaza at 16th Street are so filthy that Supervisor Hillary Ronen, who represents the Mission District, and BART board member Bevan Dufty started helping clean it up themselves. Ronen called the space “unbelievably filthy” and “disgraceful” in 2017.

BART says it went with glass over sand-blast cleaning because industrial-use sand “contains crystalline silica and has been found to be hazardous to employees.”

OSHA warns that “silica sand can cause silicosis, lung cancer, and breathing problems” for cleaners. But the same materials also inform workers that glass has “the potential to cause lung damage” as well. Recommended less toxic materials include dry ice, baking soda, and sponge granules.

In any case, the cleaning was a prelude to a larger project set to continue through September 21, which will see the plaza partially closed every day to be “resurfaced with a material called Thermoplast,” which BART promises “will be easier to clean, as it repels liquids rather than absorbing them, as the current asphalt does.”

The construction news site For Construction Pros identifies thermoplastic as “a plastic material made of binder, pigments, filler, and glass beads,” often used for painting lines on asphalt in streets and parking lots because of its capacity to “bond or ‘burn in’ to the pavement surface.” Thermoplastic is heated to a liquid state when applied but cools rapidly.

Half of the plaza will be closed at one time during the process, but BART promises 16th Street Station will remain open and accessible throughout the 11-day overhaul.

In the meantime, few things are as therapeutic for Mission commuters as watching years upon years of concentrated grime blasted away. Behold:

• BART Twitter
• Thermoplastic Pavement Striping [Construction Pros]
• 16th Street Plaza Partly Closed [BART]
• Politicians Clean 16th Street Station [Curbed SF]
• Abrasive Cleaning [OSHA]