Muni wants to share 100 of its stops with the growing swarm of private commuter shuttles, give priority to its own buses and charge a fee to the private operators in an effort to impose some order on the out-of-control industry.

The Municipal Transportation Agency is proposing an 18-month test of a shuttle policy designed to support the private buses, which transport as many as 35,000 workers a day, mostly to and from tech companies in Silicon Valley, while reducing conflicts with Muni buses and establishing guidelines to help the private and public buses get along.

"We're trying to be balanced," said Carli Paine, project manager. "This is our best approach. It provides for operation of the shuttles and recognizes their benefits while minimizing the impacts on Muni."

The framework of the plan, which is still being developed, will be presented to a committee of the MTA Board of Directors on Friday.

Many of the private shuttles are chartered by big-name tech firms including Facebook, Google, Yahoo, Apple, Genentech, Intuit and eBay. San Francisco schools and other businesses, including UCSF, Academy of Arts University, Zynga and Gap also run shuttles as does the Presidio. All would be covered by the policy.

City law restricts use of Muni stops to the transit agency's buses and railcars but allows the Municipal Transportation Agency to establish "stands" as needed. The agency's approach so far has been a combination of looking the other way, trying to work out problems with shuttle operators and issuing citations.

Complaints increase

But as the number of shuttles has boomed in recent years, so have complaints about shuttles forcing Muni buses to disgorge passengers in the middle of streets, blocking crosswalks, backing up traffic, traveling on restricted streets and interfering with bicycles using bike lanes. Citations have been issued, Paine said, but because there's no ordinance governing shuttles, they're lumped in with all other tickets for illegal use of Muni stops, and it's difficult to tell how many were issued to shuttles.

"We've been dealing with it on a complaint basis and with ad hoc, site-by-site solutions," she said. "That's not going to continue to work for us, and it doesn't create a consistent policy for the shuttle providers."

The agency's test plan would:

-- Create a network of about 100 Muni stops suitable for sharing with private shuttle buses.

-- Establish guidelines giving Muni buses priority, limiting the amount of time at stops, and requiring shuttles to pull to the front of the stop.

-- Require shuttles to display an identifying placard.

-- Prohibit shuttles without permits from using Muni stops.

-- Step up enforcement, issuing citations to shuttles without permits or using unauthorized Muni stops.

-- Require operators, some of whom have been reluctant, to share with the MTA data including the number of passengers, routes and boarding locations.

-- Charge operators a still-undetermined fee based on covering the costs of the program and helping to maintain the stops.

The MTA has been working with some of the companies that operate shuttles, Paine said, and they've been briefed on the agency's plans.

Genentech's response

"We look forward to working with SFMTA to create a comprehensive program that allows Genentech to continue providing practical transportation solutions for our employees that help to limit the number of cars on the road and reduce CO2 emissions," said a Genentech spokeswoman, Lisa Slater.

Representatives of Google, which operates the most shuttles in San Francisco, did not respond to a request for comment Thursday. Paine said some of the shuttle providers' concerns included controlling the costs of the program, perhaps by using technology, avoiding unnecessary bureaucracy and increasing the number of shared stops.

Paine said the agency is willing to consider more stops - shuttles now use about 250 of Muni's 2,500 stops, she said - and will continue to work with shuttle operators on a plan that will allow the private buses to coexist with public transportation.

Details of the 18-month test project, including fees, are expected to be worked out this summer, then presented to the MTA board and the Board of Supervisors for approval, possibly this fall, with the goal of starting the program in early 2014.

Michael Cabanatuan is a San Francisco Chronicle staff writer. E-mail: mcabanatuan@sfchronicle.com Twitter: @ctuan