The long civic struggle to tame the growth of the rapidly expanding skyline here may have produced the most comprehensive and stringent downtown zoning laws ever imposed in a major United States city. Height, density, location, and details as specific as architectural style are among the proposals in the Downtown Plan up for adoption this month by the San Francisco Board of Supervisors.
The plan, too, is likely to include two controversial new amendments. One would set annual limits on new construction. The other is an unprecedented requirement that office developers pay for child-care centers.
San Francisco's Downtown Plan is a curiosity among planners nationwide. Most planners are used to ``more abstract zoning policies . . . which generally fall into two categories: If building is booming they want to channel growth, and if it isn't they want to promote growth,'' says Frank So, deputy director of the American Planning Association.
San Francisco planners have tackled traditional urban-development problems in a package -- rather than in the traditional piecemeal manner, Mr. So says.
``It goes a long way and is very sophisticated. It has linked up what others have tried to do independently in an enormous area [one square mile of downtown],'' admits Tom Jones, an architect and consultant to neighborhood groups that have criticized the plan for rechanneling growth instead of slowing it.
Though developed by the city planning department, the plan reflects pressures from the diversity of city residents. The city is an increasingly gentrified community of white-collar workers with strong interests in a booming economy. Skyscrapers, which doubled their annual growth in the 1980s, symbolize the economic success. Meanwhile, the city has a strong counterbalance, with roots in the environmental movement, that promotes controlled growth.
The Downtown Plan reflects the growing momentum of the controlled-growth groups. Starting in 1972, they mounted a series of municipal ballot initiatives to halt the spread of the Manhattan-like concrete canyons. They blame high-rise growth for the shadows that darken the financial district, a change in the aesthetics of the city's profile, monumental traffic congestion, parking problems, and crowded conditions that cause residential rents to rise.
Such initiatives have gained increasing support, and one was finally passed last year. It prohibits building that would cast shadows on designated open spaces.
Principal features of the Downtown Plan include:
Reducing the maximum building height from 700 feet to 550 feet.
Creating building formulas that would reduce square footage and require ``more expressive, sculptured building tops.'' Buildings would be tapered at the top, like wedding cakes, to allow more light on the streets and to maintain the older, quaint character of the city.
Preserving 251 specific historic buildings. Owners of these buildings would be able to sell the unused air rights over their buildings to developers who want to build tall buildings elsewhere.
Requiring open space to be provided in all new developments. The ratio would be one square foot of open space for each 50 square feet of building area.
Current ordinances requiring builders to contribute money to transit and new housing stock are expected to be incorporated into the plan.
While none of these points alone is unique, the sheer scope of the plan is unprecedented, professional planners say. For example, the transfer of ``development rights,'' such as air rights over a building, has been tried before but never on such a large scale. City planners elsewhere will be watching to see what the market will be for these air rights.
The Downtown Plan, in its current form, would cost developers 15 percent more to construct new buildings, and would reduce the current pace of building 30 percent, says Dick Morten, deputy director of the Chamber of Commerce of San Francisco.
Even so, the chamber has endorsed the plan. It does ``provide a measure of good for the long-term economic benefit of the city,'' he says. But some proposed amendments to the plan, such as an annual cap on the amount of space for high-rise construction, would create market uncertainty that would be bad for the economy, he adds.
Mayor Dianne Feinstein backs an annual limit -- 950,000 square feet -- to new high-rise building. But growth-control groups are pushing for limits as low as 500,000 square feet -- roughly equal to the square footage of the TransAmerica building, the distinctive pyramid on the local skyline.
``This plan is only cutting down what's allowable on a lot. But we can't continue with the current pace of growth,'' says Dick Grosboll, of San Francisco Tomorrow, a growth-control group.
``To say that this [plan] does more than any other city is ignoring that this is a unique city,'' he says, noting San Francisco is surrounded on three sides by water and has limited access routes. Consequently, the city's very geography calls for stricter controls to begin with, he says.
Advocates of ``slow growth'' say the Downtown Plan, without the annual cap on building, would dictate only architectural tastes, not long-term planning.