Palo Alto residents and council members routinely lament downtown's worsening parking crisis, but a new study indicates that the area actually has enough spots to accommodate the recent surge in office development.

This conclusion, however, comes with a caveat: downtown's parking supply is only sufficient if the residential neighborhoods surrounding the commercial core are willing to share the free parking on their blocks with commuters.

From the city's perspective, that's a significant sticking point. At Wednesday night's review of the new Downtown Cap study -- an in-depth analysis performed by the firm Dyett & Bhatia Urban and Regional Planners that aims to measure downtown's capacity for further development -- several Planning and Transportation Commission members made it clear that the current situation, with downtown commuters filling up residential blocks during business hours, is unacceptable.

That has also been the position of downtown residents and of the City Council, which earlier this year directed staff to design a permit program that would set time limits for cars parking on neighborhood streets. The city is also looking to launch new shuttles, start a program that would encourage auto commuters to take other modes of transportation, and build new garages.

But the new study suggests the parking crisis isn't so much a problem of supply as one of preference. The study, which is being conducted in phases, stresses that downtown's existing garages remain underused. The area's off-street facilities, the study states, are "below full capacity at peak periods, with garages overall and permit spaces in particular showing significant vacancies." There are also some blocks "with a few open spaces available."

"In short, the city could improve parking with strategies that address not just new supply but better management of existing facilities," the study states. "The overall parking supply is sufficient to meet demand, if the community accepts that many downtown employees park for free on neighborhood streets."

Just about everyone agreed on Wednesday that that's a big "if." Michael Griffin, a Downtown North resident and former planning commissioner, made it clear the neighborhood has no intention of accepting any such thing.

"I think it goes without saying that it is not acceptable to the community," Griffin said.

Commissioner Michael Alcheck agreed and called downtown parking a "complex problem."

"I've been a very strong advocate of exploring parking-permit ideas, and I don't necessarily accept this notion that residents in our downtown neighborhoods have to fight hard to be able to park in front of their homes," Alcheck said.

The commission's discussion focused on the first phase of the Downtown Cap study, which is required by a 1986 law that set a limit on non-residential downtown development at 350,000 additional square feet and required the city to conduct an analysis when growth reaches 235,000 square feet. The city recently cleared the latter threshold, having added about 252,000 square of non-residential development downtown.

Even with the strong growth, parking supply remains adequate, said Sophie Martin, an associate principal at Dyett & Bhatia. She noted, however, that the parking spaces "aren't necessarily where people want to be."

"And we can only really say the supply is adequate to meet demand if we say it's OK that employees in downtown park in adjacent neighborhoods," Martin said. "Without the adjacent neighborhood parking, we start to run into supply issues."

According to the study, downtown has seen a gradual increase, though activity has "accelerated in recent years," the study states. More than half of downtown's total non-residential development since 1986 has been built over the past three years -- more than 100,000 square feet in the past two years. Downtown's vacancy rate, which stood at 9 percent in 2009, dropped to 2 percent in 2013.

Though the growth inevitably means more cars, a survey included in the study shows that more than half of the people who come to downtown Palo Alto don't drive at all. The survey, which asked 501 downtown respondents (including employees, visitors and residents) about their traveling habits, found that 44 percent of the employees who commute to Palo Alto from elsewhere rely on their cars, while 51 percent take public transit. Employees who live in Palo Alto drive to downtown alone at a higher rate (48 percent), with the balance split between public transit (30 percent), walking and biking (9 percent each), and carpooling (4 percent). Furthermore, the survey found that less than half of the people who visit downtown (but don't work there) drive alone. That rate is 32 percent among visitors from Palo Alto and 40 percent among visitors from other cities.

The study indicated that significantly more commuters than in the past are getting to downtown without using their cars. Boardings at the downtown Caltrain station are up by 51 percent since 2009, according to the study.

Even with the high rate of transit use, commissioners agreed that downtown parking is a major problem. Jessica Sullivan, the city's parking manager, said most commuters prefer to park on the streets, with parking lots as a second choice and garages as a third. This has left residents in the Professorville and Downtown North neighborhoods seething as they watch their blocks get parked up every weekday morning.

Alcheck pointed to parking as the "real concern" downtown residents have about new development downtown, "not whether we approve a few more office buildings."

The study also suggests that new development isn't the only reason for downtown's parking woes. Another is the way in which existing buildings are being used. Even though new construction accounts for less than 10 percent of the area's total square footage of buildings, much more space is now devoted to professional, personal and commercial services. Downtown is also filled with startups, which typically employ more workers per square foot than traditional offices do, the study notes.

"It is these changes in the use and building occupancy in the downtown overall that have likely contributed to increased traffic and parking demand," the study states.

In the study's next phase, existing businesses will be surveyed to determine how many people they employ and how these employees get to work. These questions also prompted the City Council to direct staff earlier this year to create a business registry, an online database that would collect such information from employers.

Whatever the numbers, commissioners agreed on Wednesday that the city will have plenty of work to do in the coming years to ease the negative consequences of growth downtown.

"I think we need to think in terms of how, in particular for people who come from far away, how to encourage them to take public transit and how to make it easier for them to take public transit," Vice Chair Arthur Keller said. "That's going to be an increasing challenge for us."