The Transbay Transit Center, which will transform the landscape of downtown SF when it opens for business in late 2017, continues to take shape out of the ground along four blocks of Natoma Street between Beale and Second. Today we get an update from Chronicle architecture critic John King on the prototype panels that have been getting tested for what will be the most notable street-facing aspect of the design, the undulating, perforated metal "skin" draping over the upper levels of the structure, as seen in the illustration above.
This design element began as glass imprinted with a white pattern to filter sunlight, as you can see in the side-by-side comparison below, but as the design's costs began to escalate, the architects came up with the compromise solution of the metal skin, shaving some $17 million off the price tag.
The interlocking diamond pattern of the perforations is derived from the work of 1970s British mathematical physicist Roger Penrose, and is meant to take on the appearance of a continuous pattern despite being composed of 6-foot-by-6-foot panels.
Testing has been ongoing, with one prototype panel rejected for too little mica in the white paint the mica-flecked paint will help the surface not be so monotonous. Next up, the architects will examine how 18 panels look all together, to make sure there are no problems before the fabricators start pumping these out.
Just to recap, there's been recent tension among the developers building high-rises in the Transbay District about paying the rising assessments they'd agreed to, which will be used to fund the second phase of construction, which involves extending the CalTrain tracks from 4th and King up Second Street, underground, to the new transit center. It turned out developers were bluffing, despite threats to sue the city, and that tension was settled earlier this year.
There remain open questions about how to fund the fancy rooftop park that is another signature element of the design, and one that helped sell it to the public back in 2007, and that may ultimately involve selling naming rights.
It's unclear whether the park will be complete when the rest of the building is in 2017, or not.
If you need a primer on how the entire building will work, and look, check out this explainer video, narrated by local voice-over maven, Peter Coyote.
All previous coverage of the Transbay Transit Center on SFist.
