Drivers crossing greater downtown San Francisco and the southern border with San Mateo County could be hit with a new toll costing them as much as $1,560 a year.

Everyone from workers to parents dropping off their kids at school could have to pay the new charge, which is designed to ease congestion and raise revenue for extra bus service, pothole repairs and bike and pedestrian improvements.

For several years, San Francisco transportation officials have considered imposing a charge to drive in targeted neighborhoods, and on Wednesday they said they hope to move forward with one or more pilot projects.

The earliest the new tolls would go into effect would be 2015, and then only for a six-month to one-year experiment to gauge public reaction and the effectiveness.

First, however, the San Francisco Board of Supervisors, in its role as the San Francisco County Transportation Authority Board, and the state Legislature would have to approve the proposal. Yet to be determined is whether voters would weigh in. The plan may need voters' support.

Next month, the supervisors could give their approval to initiate additional studies. The scenarios given the most serious consideration would:

-- Charge motorists $6 to leave the northeast sector between 3:30 and 6:30 p.m. The area roughly would be bordered by the northeast waterfront, Laguna Street on the west and 18th Street on the south. Among the affected neighborhoods would be South of Market, the Financial District, Union Square, Civic Center, Hayes Valley, the Mission, Chinatown, North Beach, Cathedral Hill, Mission Bay and Potrero Hill.

-- Charge $3 in each direction to cross San Francisco's southern border at Interstate 280, Highway 101, Skyline Boulevard, Lake Merced Boulevard, San Jose Avenue, Mission Street, Geneva Avenue, Junipero Serra Boulevard and Bayshore Boulevard from 6:30 to 9:30 a.m. and 3:30 to 6:30 p.m.

-- Charge to cross the southern border and include an extra fee to park in private lots in the northeast sector during the peak commute times. The exact cost for this hybrid version has not been determined, but likely would have a cumulative cap of about $6.

Including private parking would dovetail into the city's new SFpark experiment, which bases the cost to park at meters and in city-owned garages on demand to create more parking and keep drivers from circling in search of a space. Officials have not settled on how tolls would be collected. Possibilities include the FasTrak system now used on Bay Area bridges, paying remotely by cell phone or setting up pre-paid accounts in which the toll would be deducted every time the vehicle passes detection cameras that capture license plates.

Program goals

The exact hours and toll charges may change as the pilot projects are developed, said Zabe Bent, principal transportation planner with the San Francisco County Transportation Authority. As envisioned, there would be no tolls on weekends.

Planners also are contemplating discounts for disabled and low-income drivers, residents who live in a toll zone, drivers who also pay bridge tolls and businesses with a fleet of trucks. The program could generate an estimated $60 million to $80 million in net revenue annually, authority officials estimate.

Other cities, including London, Stockholm and Singapore, have enacted congestion-based tolls. If San Francisco proceeds, it would be the largest-scale program in the United States.

The goal is to get commuters out of their cars to reduce congestion and to cut greenhouse gas emissions - benefits that are needed now and more so as the region's population is expected to grow, say advocates of congestion pricing.

The toll could change driving habits for some. But others, who will not - or cannot - change their commutes would help fund transportation improvements. Jose Luis Moscovich, executive director of the Transportation Authority, said that winning public support would be predicated on providing safe, convenient and affordable alternatives to driving.

"We need to give you choices," he said.

Questionable tactic

Critics say that alternatives to driving are admirable, but that placing the burden on drivers is the wrong solution.

"You'd be pulling up the welcome mat in San Francisco," said Ken Cleaveland, director of government and public affairs for Building Owners and Managers Association of San Francisco, which represents commercial real estate interests. "We shouldn't make it harder for people to want to work here and come to the city to shop in our stores, attend our theaters and eat in our restaurants. You will drive away business if you scapegoat people for driving their cars."

Mayor Gavin Newsom, the state's lieutenant governor-elect who is leaving City Hall in January, also opposes implementing a local toll, or even talking about implementing one, "during one of the worst economic downturns in the history of the city." Two years ago, Newsom embraced the concept of congestion pricing, saying a sensible model would be "the single greatest step we can take to protect our environment and improve our quality of life." But he now says the last thing the city should do is give employers and visitors pause in deciding whether to come to San Francisco or go elsewhere.

San Francisco Supervisor Ross Mirkarimi, who chairs the Transportation Authority board, said it's important to take the long view and focus on the potential benefits, "if we're serious about greening and having a workable transportation model."

He said the key will be to find the right price that will help the city meet its environmental and congestion-relief goals without harming business or angering residents. If done right, he said, "San Francisco could be a pioneer in the United States."