Colorful Expression Fall/Winter 2022

Glass Flooring Brings Art and Light to San Francisco Subway

The city of San Francisco is one filled with color and character, making it the perfect place for an artistic new glass flooring system. The city’s Union Square is known for its large collection of department stores, upscale boutiques, hotels and fine dining. Adding to this famed hub is the Central Subway—Union Square Market Street Station, which now features a unique two-hour fire-rated glass floor system by Safti First®. DLR Group | Kwan Henmi based in San Francisco was the project architect and ACR Glass & Doors of Oakland, Calif., was the contract glazier.

The glass floor sits on the surface of Union Square, and also acts as a light well for the station below. In order to comply with fire-rated code requirements, the transparent floor needed to meet a two-hour fire-resistive rating.

This 1,100 square foot floor was built with structural beams at the perimeter and intermediates to support a two-hour, fire-resistive walkable glass surface. The largest single lite of glass measure 67 by 59 inches.

The design features artwork by Hughen/Starkweather titled “Convergence: Commute Patters,” referring to a convergence as a place where ocean currents or airflows meet, marked by an upwelling of air or down-welling of water. Pulp Studios, based in Gardena, Calif., brought this artwork to life by digitally printing it on glass with a SentryGlasPlus interlayer and an anti-slip walking surface.

The 74-panel, site-specific, glass artwork comprises the facade, roof deck and ceiling of the Union Square Central subway station. Embedded in the layers of glass is a precise topographic map of San Francisco along with painted circles that reference Bay Area commute pattern densities. Similar to a standard data infographic, the larger circles in the artwork represent higher numbers of commuters.

Due to the station’s busy nature, the architects also wanted to be sure and allow an abundance of natural light to travel through the interior spaces, reducing the demand for artificial lighting. The glass flooring system allowed them to increase vision and transparency by using floor-to-ceiling glass walls to connect, instead of separate, indoor with outdoor spaces.

According to Safti First, the GPX® FireFloor System is USA-made and listed by UL and Intertek. The flooring is a complete fire-resistive glass and framing assembly that meets ASTM E-119/UL 263 up to two hours, and has the largest tested and listed individual glass panel sizes and features a top-loaded design for easy installation, according to the company.

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