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How high San Francisco? Treasure Island tower raises important questions

How high is too high?

The "Sun Tower" proposed for Treasure Island, now planned to be "somewhere between 450 and 650 feet", could dramatically change the San Francisco skyline. For comparison, the Transamerica Building is 853 feet tall, the Western Bay Bridge Towers 526, and One Rincon Hill 605, and the proposed Transbay Terminal tower could possibly exceed 1,200 feet.

The Sierra Club has not in the past taken positions about the heights of these buildings, but it is now considering the Sun Tower in the context of redevelopment plans for currently underutilized Treasure Island.

High-density housing is a cornerstone of smart and sustainable development. The Treasure Island proposal calls for a core residential area of 60 - 80 homes per acre - roughly as dense as the Marina District. Remarkably, 90% of these homes will be within a 12-minute walk of the island's transit hub; strike a blow for energy conservation. The residential buildings will include mid-rises and high-rises; the Sun Tower, named for the 400-foot Tower of the Sun that dominated the 1939 - 40 Golden Gate Exposition, will be the highest. Situated on the San Francisco side of the island near the waterfront, the tower will be conspicuous in Bay views from all directions, inviting judgments that are sure to be diverse.

In a city of severely limited acreage, constructing hundreds of homes within the space of a handful of single-family homes has some obvious benefits. Today we have the technology to reach higher into the sky. The question then becomes, would 80 stories be even better? How about 100? How do participants in the public planning process decide how far to go?

Jack Sylvan, of the Mayor's Office of Base Reuse and Real Estate Development, points out that "the Western U.S. has been much slower to embrace tall buildings than many other cities," citing the recently approved Chicago Spire: a residential condo building that will be the tallest in the US at 2,000 feet and more than twice as tall as the tallest building in San Francisco.

The most obvious benefits of high- and mid-rises are a reduction in sprawl, increase in access to public transit, walkable distances to shopping and restaurants, decreased dependence on the private automobile, and preservation of open space. The current plan for roughly 6,000 residences will leave far more open space than the original plan for only 2,000 residential units.

There could be social benefits as well. The plan is to encourage residents to interact with each other and create community. Inviting public spaces and common meeting places for transportation access have been included in the plan. Cafes and other retail will be strategically placed within residential buildings to create a more "permeable" ground floor, as an alternative to having a parking structure on the pedestrian level. The island's townhouse-style 3 - 4-story buildings will have actual stoops facing the street or sidewalk. The intention is to create many of the same neighborhood benefits that homeowners and renters seek and find in a more traditional neighborhood.

Aesthetics will also need to be considered. Will the building enhance or overwhelm the Bay Area landscape? Architect Craig Hartman of Skidmore, Owings & Merrill, lead architect for the project, explains how desire for visual appeal has shaped the latest development plan. The skyline is designed to be highly symbolic, with the Sun Tower as almost a kind of campanile, marking the port of arrival at the ferry terminal much as does the Ferry Building clock tower across the channel. "It's important that we make a statement with this building. It is meant to be a graceful presence in the skyline; a marker for San Francisco's urban and environmental intentions." He sees the tower as a testament to sustainable development and a way to emphasize some of the ecological goals of the island plan. There will be several other "mini-neighborhoods" within the residential area, each represented in the skyline by a mid-rise tower.

So how do you make a high-rise seem graceful? According to Hartman, the aspect ratio, or ratio of width to height, has a lot to do with achieving that effect. Ideally, he says, the height should be at least 6 - 7 times the width. Otherwise, the building will look squat and unattractive. But at what point do you stop? When asked about the pending 2,000-foot Chicago Spire, Hartman replied, "A building of that size would just be totally inappropriate in that setting. It would take away some of the symbolic power of the city of San Francisco itself."

As currently planned, the tower could be considerably higher than the neighboring 338-foot-high Yerba Buena Island, which will probably play a part in determining an appropriate height scale for the location.

The comparison to One Rincon Hill is almost unavoidable. At 60 stories, that is by far the tallest building in the immediate area and one of the tallest residential buildings west of the Mississippi. It's difficult to miss when you look towards downtown. Newspaper reports suggest that the public response to it is pretty negative. Its stature may be softened eventually, however, when, as planned, additional similarly scaled buildings are added to the area. On Treasure Island also, there are plans to "mound" buildings of varying size to create an aesthetically pleasing skyline. Still, the Sun Tower is designed to be conspicuous, and the designers will face a challenge to create a design that the public can embrace.

In the coming months, as public consideration continues on plans for Treasure Island, the Sierra Club's San Francisco Group will be weighing the above concerns - along with questions about seismic stability, emergency evacuation, and affordability - and considering whether to take a position regarding the height of the Sun Tower. If you have thoughts to contribute to the process, contact Steven Chapman, chair of the San Francisco Group Conservation Committee, at steven -at- or call conservation organizer Brad Johnson at (415) 200-8975.


2007 San Francisco Sierra Club Yodeler


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