Central Subway – Union Square Market Street Station (UMS)
|Location:||San Francisco, California|
|Client:||San Francisco Municipal Transportation Agency (SFMTA)|
|Project Type:||Transportation Stations|
|Cost of Project:||$160 Million|
Prime, Civil & Stuctural – Parsons Brinkerhoff
Architecture – Robin Chiang & Company
Union Square is one of the premiere retail centers in the world. In beautiful and sophisticated San Francisco it thrives because of its convenient location: near the financial district, convention center, museums, luxury hotels and Chinatown; as well as its compact size: contained within not much more than a dozen city blocks. Prestige brands have built stand-alone boutiques around the square and surrounding streets. Major department and specialist stores abound. Arguably the commercial heart of San Francisco is literally the popular and public one block square itself. Redesigned and rebuilt for the 21st century it showcases a blend of new and old in the tradition of the city that was itself resurrected from ruins a century ago.
San Francisco’s Central Subway project, under construction until 2018, includes 3 new underground light rail stations beneath the congested Stockton Street corridor. Robin Chiang & Company (RCC) is Architect for the Union Square Market Street Station (UMS) within the context of San Francisco’s retail center. At the south end the station merges with existing Powell station and uses BART’s entry at the Apple store. At the north end the station entrance is in one corner of Union Square. The station concourse level is approximately 700’ long and slopes in conformance with the grade of Stockton Street. The station platform level is approximately 210’ long and is over 70’ below ground. In between is an enclosed mezzanine containing station utilities and exit corridors.
Our design theme for UMS will build upon the concepts and ideas developed by SFMTA’s consultant team and vetted in public meetings between SFMTA and constituent merchants and businesses. The setting and purpose of Union Square, as a premiere retail center, require more refinement than the usual finishing of an underground tunnel. Although the station architecture must be functional, rugged and durable in appearance we believe it should be inspired by and remind visitors of design in the retail world—the pinnacle being haut couture or high fashion. We sought to accomplish that without tying appearance to a particular style. By expressing the raw materials of the tunnel volume and making it look as though just enough finishes and components have been included to accommodate passengers, the design could suggest a model in the process of being draped by a couturier—the tunnel as the human body and the station as its stylish outfit.
On the surface Union Square will appear intact and as it is today. However, as depicted in the design concept, planted and stepped terraces on Geary Street will be modified to cascade toward the new station entrance and a more generous sidewalk area will be created.
Below the street level the high fashion architectural theme will reveal itself. The great excavation and tunneling required for the station’s construction will be celebrated with exposed rough cementitious wall materials—smoother, finer grain at concourse level and rougher, coarser grain further down at platform level. Visitors to the concourse will be treated to walls covered with sleek modular panels (containing transit information, area information, wayfinding direction, advertising, etc.) positioned at eye level and screening the finer grain, but rough finishes where hands and feet may touch them. Spaces and gaps above, below and in-between the panels will reveal discrete portions and swathes of the tunnel’s cementitious wall surfaces in peek-a-boo fashion.
Descending to the platform level on the long escalators or stairs visitors will pass between a web of enormous transverse and longitudinal beams clad in metal, but expressed honestly as the colossal structural members that have been calculated to maintain the integrity of the tunnel’s shape against the thrust and pressures from outside at such a depth below the ground.
Similar to the handling of architectural treatment at concourse level the platform level’s finishes that people can touch will be sleek and modular and positioned to protect the tunnel’s cementitious walls from the wear and tear of hands and feet. Finely finished components (such as handrails, acoustical treatment, flooring. lighting, signage, utility chases, overhead power, etc.) will be designed to appear as an ensemble of interventions within the tunnel—in the cosmetic manner of veils and jewels selected to adorn the human body.