Drivers in San Francisco are known to grumble when it comes to street parking, but new data suggest that at least some of the stress can be eased under the city's innovative parking-management program.

The upshot: The city's parking cops are issuing fewer tickets for meter violations in neighborhoods where the experiment has been applied.

"By making it easier to pay, parking anxiety is reduced and people don't have to be as worried about getting a parking ticket," Jay Primus, manager of the San Francisco Municipal Transportation Agency's SFpark program, said Wednesday.

The old meters in neighborhoods not covered by SFpark only accept payment by coins and prepaid parking cards. The new meters also allow payment by credit cards and mobile phones.

In addition, the new meters have less restrictive time limits, generally allowing drivers to park for four hours or more. For a 45-cent fee, drivers even can add more time remotely if their meter is about to expire.

The decrease in parking citations was what the architects of SFpark predicted when the program was rolled out, and now a preliminary analysis of data confirms that.

The new study compared revenue at about 4,500 metered spaces in the first six months of 2010 when the old meters were in place and the first six months of 2011 after the new meters were installed.

Prior to the new meters, 55 percent of the revenue came from payments drivers used to buy time and 45 percent from fines. After the new meters went in, the amount from payments increased to 70 percent and the amount from fines plummeted to 30 percent.

Fines for meter violations in San Francisco are among the steepest in the nation, at $55 or $65, depending on the neighborhood.

The San Francisco Municipal Transportation Agency had anticipated generating $104 million from parking fines, which include meter violations, for the fiscal year that ends June 30, but now is looking at about $7 million less.

And even though parking meter revenue is down overall in San Francisco, the decrease is lower at the upgraded SFpark meters - a 3 percent drop instead of the 14 percent decline at the old meters.

Gross revenue from the new meters actually increased, but credit card and data transmission fees ate up about a third of the gain, officials said.

In all, SFpark operates in eight pilot areas, including Hayes Valley, the Fillmore, Fisherman's Wharf and the Mission, and accounting for about a quarter of the city's 26,800 metered spaces.

Making parking more convenient and causing less angst for drivers is a side benefit to the program, whose core mission is to reduce traffic congestion and air pollution.

The federally funded and internationally watched experiment bases parking prices on demand. The goal is to have about one parking space available on every block at any given time to decrease the need for drivers to circle the block looking for a free space.

Prices may be altered no more than once a month - and then by no more than 50 cents lower or 25 cents higher - to try to change drivers' parking habits.