For Terry Giannini, the breaking point came in early November, when work crews placed bags over the parking meters at San Bruno Avenue and Bacon Street.

Giannini could see them through the plate-glass windows of his barbershop, with its yellowing 49ers posters on the walls and a striped pole out front. Within two days, workers had sawed off nine meters on San Bruno, the final batch for a project that would eliminate 37 parking spaces from a busy nine-block stretch.

The San Bruno Avenue Multimodal Improvement Project will turn a scruffy neighborhood in San Francisco’s Portola district into a vision of the city’s future: wide sidewalks, short crosswalks, big “bulb-out” curbs and bus zones long enough to fit two coaches.

Such street designs are proliferating throughout the city, pointing to a distinct political shift: Cars no longer reign supreme in San Francisco. Instead, the mayor and transportation agency are making swift transit and pedestrian safety the priority.

In the Portola, these ideals have met stout resistance — particularly from merchants who say they will lose business when customers can’t find a place to park.

“I’ve had customers who are driving around in circles,” said Giannini, a bespectacled man with a shock of blond hair and a penchant for Hawaiian shirts. “I tell them to come half an hour early, and they can’t find parking. So they’re leaving.”

His lease is up at the end of the year and, after nearly 30 years of cutting hair on San Bruno, he may not renew it.

Irate shop owners have the ear of district Supervisor Hillary Ronen, who sent the San Francisco Municipal Transportation Agency two sharply worded letters in October and November. By that point the project — approved in 2016 — was near completion: Major elements such as sidewalk extensions and a new traffic signal at Felton Street are done, and the rest of the work is expected to wrap up early next year.

Ronen criticized the agency for failing to communicate how many parking spaces would be cut, for not providing adequate Chinese translation during public meetings and for dismissing residents’ concerns.

She asked for several modifications. Among them: that the transit agency consider shrinking parking spaces to boost capacity. She also wants to keep a bus stop in front of Walgreens at San Bruno and Felton Street. The agency plans to move it down the street, to an area crammed with small shops and a takeout restaurant — where the merchants say parking is more precious.

The agency has already made concessions. Initially, the San Bruno plan called for 45 parking spaces to be stripped out, but in November, the Municipal Transportation Agency offered to restore eight of them. Agency staff warned, however, that the last-minute change would make bus service less reliable.

Transit Planning Manager Sean Kennedy said his team intends to move the bus stop, while continuing to engage with the community.

“Of course we all really want pedestrian safety and transit improvements to happen, and the Portola really needed this project,” Ronen said. “But they can’t just treat all neighborhood corridors equally and disrespect merchants. The Portola is not the Mission ... it’s not a neighborhood where you can survive easily without a car.”

San Francisco has a long tradition of political give-and-take when it comes to transportation, with projects getting significantly delayed or diluted before they come to the Board of Directors for a vote. It’s not uncommon for residents and business owners to ignore a project during the approval process, and then complain when construction is nearly finished — and for agency staff to try to appease them.

But that’s starting to change. When Mayor London Breed took office, she directed the city to accelerate safety improvements and bike-lane infrastructure. In recent months, the agency’s board has increased pressure on agency management to deliver better bus and train service. New transportation chief Jeffrey Tumlin is outspoken about placing bikes and transit on equal footing with cars.

“I am not a better person when I bike to work, but I do take up one-tenth of the roadway space as when I drive to work,” Tumlin told reporters last month, in his first public address at City Hall. “So in order to make it possible for people to continue to drive in San Francisco when they need to, we have no choice but to prioritize making it easier, more convenient, safer, for the rest of us to not drive.”

He added: “And that is not about the virtue of one mode over another. It’s about simple math.”

Five years ago, staff at the Municipal Transportation Agency counted the city’s parking capacity and found 275,450 spaces on public streets, a tenth of them metered. Since then, the agency has redoubled its efforts to end traffic deaths, move people and freight more efficiently and make it easier for Muni riders to board buses — all of which translates into less storage space for cars.

Though they’re not keeping track, officials say they’ve traded hundreds of parking spaces for bike lanes, bus or loading zones, and wider curbs. For example, a major improvement project on Masonic Avenue, completed last year, consumed 167 spaces.

In the Portola, the people-over-cars calculus means eliminating parking to make more room for 42,000 passengers who board the 8-Bayshore and 9-San Bruno buses every day. It makes a big difference to riders like Xavier Goins when the buses run faster, though he’d like to see service increased.

“Sometimes it’s so packed in the mornings that I can’t get on,” said Goins, who was standing on a recent workday at the stop at San Bruno and Felton.

San Bruno Avenue illustrates a street design revolution that’s building momentum in San Francisco. In recent months, the transit board voted to ban cars on Market Street, add protected bike lanes in the South of Market area, close a block of Octavia Boulevard to car traffic, shave parking from Haight Street to speed up Muni’s 6 and 7 bus lines, and make a block of Page Street one-way to prevent cars from using it as a shortcut to Highway 101.

The board also enacted a new quick-build process that allows the directors to greenlight a list of projects at once, cutting through the bureaucratic morass.

These ideas were once radical. Now they have support from a growing coalition of bicycle activists and transit enthusiasts who pack the board meetings whenever a big decision is on the table.

Ten years ago, “we’d go to speak at a meeting, and there would be this feeling of, ‘OK, at least they heard us,’” said veteran cyclist Paul Valdez, who moved to the city almost 30 years ago. Now, he said, city leaders see the urgency to get cars off the street. “And things are getting done.”

Yet others find the loss of parking or traffic lanes disorienting. Some conflate transformation of the streets with larger economic shifts that have rattled San Francisco. When the agency painted red bus lanes on Mission Street in 2016, many residents and merchant groups saw the thick crimson stripes as a sign of gentrification. They said the neighborhood’s old legacy businesses would die if motorists had to navigate a maze of transit-only lanes and forced turns.

“Everyone was screaming for the project to be undone, and it wasn’t — it stayed,” said board Director Cheryl Brinkman. “We just weathered the storm.”

She sighed. “I just wish the merchants would realize we can’t deliver them more customers in cars.”

Back on San Bruno, the anguish is palpable. Patrick Connon, a cabinetmaker who drives his truck to the avenue for lunch, recently found himself orbiting the block in search of parking. He was so incensed that he started a petition, circulating it at Four Barrel Coffee, Fat Beli Deli and the aptly named Bus Stop Liquors & Deli. It has about 300 signatures.

On a Friday morning, Connon sat in the Subway sandwich shop at San Bruno and Burrows Street. He spread several maps and diagrams on a table — detailed plans for the multimodal project, to which he’d added circles denoting every lost parking space. He looked crestfallen.

“I’m a voter, I’m a taxpayer,” he said. “Why should my rights be less than a bus rider’s rights?”

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan