San Francisco's grand experiment to see whether traffic congestion and greenhouse gas emissions can be reduced by micromanaging the supply of public parking through price manipulation took center stage Thursday at a national transportation conference held in the city.

Attending the meeting were transportation officials from across the country who one day may want to start a similar project back home.

The SFpark demonstration, backed with nearly $20 million in federal funding, sets parking rates at curbside spaces and in public garages based on demand. If it works as envisioned, at least one parking spot per block will always be available, as some drivers - influenced by cost - will opt to park elsewhere and when rates are lower.

The aim is to reduce the need to circle the block hunting for an open space. Drivers can access information on parking availability and pricing via smart phone, the Internet and electronic signs that will be posted around town.

"The theory is great," said Allen Greenberg, senior policy analyst with the Federal Highway Administration.

The feds have hired an independent evaluation team to track the program's successes and failures. Team leader Carol Zimmerman, who spoke at the National Association of City Transportation Officials two-day conference, said a robust assessment will review everything from the change of air quality, the time it takes to find a space, the speed of traffic, sales tax revenue, the demand on the information technology and public perception to determine the effectiveness of SFpark. The final report is due in January 2013.

- Rachel Gordon

A costly problem: Each foreclosure costs San Francisco an average of $19,229 in increased safety inspections, police and fire calls, trash removal and maintenance, according to a new report from two nonprofits.

All told, the city has probably spent a total of $73.4 million on homes that have gone under water and been foreclosed by banks, according to the report by Alliance of Californians for Community Empowerment and the California Reinvestment Coalition.

On top of that, they said, the city has lost $42 million in tax revenue.

The city's politicians blame Wall Street.

"Wall Street's actions wiped out the life savings and home equity of many families," said Assessor-Recorder Phil Ting. The city's Bayview neighborhood has been particularly hard-hit by foreclosures, said Supervisor Malia Cohen, who represents the neighborhood and whose condo was foreclosed last year. The value of homes in the Bayview have dropped 30 to 50 percent since 2007, the report said.

"It has a devastating impact on the district," she said.

The group called on the state to pass a number of laws to help homeowners, including a fee banks have to pay when they foreclose a home and a requirement that banks attend mandatory mediation sessions with the owner. They said they hoped the banks that own foreclosed properties could also be forced to clean up their blighted buildings.

- Will Kane

Visualize this: To examine the public art that will soon go up at the North Beach library, all you have to do is close your eyes.

The to-be-built library will feature a soundtrack of noises from around the neighborhood, as designed by audio artist and North Beach resident Bill Fontana. His idea for a "sound sculpture" beat out two other finalists at the Arts Commission's Visual Arts Committee meeting Wednesday.

Fontana proposed to build a series of small loudspeakers that would play "a changing mix of sounds" taken from the North Beach neighborhood.

In an e-mail, Fontana wrote, "I came up with the idea of the sound sculpture as a response to the architectural design of the building.

"I am excited by the win and the fact that this permanent sound sculpture will also be there for my children growing up in North Beach, and they will have this kind of legacy in that community," he added.

- Stephanie Lee