State Assemblyman David Chiu dreams of a Bay Area transportation system that would rival London or Tokyo, where trains and buses are faster and more convenient than driving.

Getting there won’t be easy. The region has 27 transit agencies that don’t play well together. Each is a distinct fiefdom with its own map, its own fare structure, and its own interpretation of a “youth,” a “senior” or a “low-income rider.” Schedules rarely sync up. A few outliers — the ACE and Capitol Corridor trains — don’t accept Clipper cards.

As a result, only 3% of all trips in the Bay Area are made on transit, Chiu said. People may complain about freeway traffic jams and pollution from automobiles, but they still choose to drive. Ridership across all transit systems in the nine counties fell by 5.2% between 2016 and 2018.

“At the same time that all these jurisdictions are making investment in transit, people are taking transit less,” Chiu said. “They’re getting into their cars. They’re driving by themselves. They’re increasing congestion.”

His solution: Start with the basics. The San Francisco Democrat’s new bill, The Bay Area Seamless Transit Act, or AB2057, will require cities and counties to charge the same bus fare, to apply the same discounts for people transferring from one bus line to another, and to define each population, such as youths and seniors, in the same terms.

The legislation would also require agencies to use the same regional transit map, smartphone apps and Clipper card payment technology, to make it easier for people to navigate from one system to another.

People shun transit in part because it’s complex and intimidating, Chiu said.

“Imagine if you were in your car and you had to switch phone apps every time you traveled from one freeway to another,” he added.

Chiu also wants to start the harder, more complicated work of linking schedules among transit agencies and automatically applying a discount when riders jump from one to another.

Additionally, he wants agencies to work together on capital projects, to avert such outcomes as the new Larkspur SMART terminal, which requires about a 10-minute walk from the Larkspur ferry, across a street and through a shopping mall. His bill would set up a task force to begin that larger institutional change.

That notion appealed to Terry Taplin, who does not own a car and relies on a combination of BART and buses to get from his home in Berkeley to see his spouse in Richmond. The couple live separately “because of housing costs and family obligations,” Taplin said.

“The big anxiety is missing a transfer by three minutes, which could make me 45 minutes late,” he added.

Two other people who would benefit from a more seamless transit system are Chiu and his wife, who both drive to work each day to avoid long, rambling bus-and-train commutes.

They live in the Candlestick Point neighborhood of Bayview, and Chiu would have to take Muni, BART and Amtrak before walking a mile to get to the Capitol building in Sacramento. His wife works at a nonprofit in San Jose — a long journey on Caltrain with a 2-mile gap at the end.

“It’s far quicker for me to drive an hour and 45 minutes” on the freeway, Chiu said. “Multiply that by any number of people trying to get from Point A to Point B.”

Yet transportation officials were less certain. While several praised Chiu’s vision, they also wondered whether cash-strapped transit agencies would have to fund the changes.

“The devil’s in the details,” said Elsa Ortiz, vice president of AC Transit’s board of directors.

Randy Rentschler, legislative director of the Metropolitan Transportation Commission, noted that the Bay Area’s disparate schedules, maps and fares have frustrated commuters for decades. Clipper has 18,000 fare combinations for people moving between systems, “because that’s what the transit agencies have determined,” he said.

Yet he also wondered whether a more top-down order would be palatable to goverment agencies that have enjoyed autonomy since the 1970s.

“Local control seems to be a religion in the Bay Area,” Rentschler said.

Supporters welcome state intervention.

“This is really critical,” said Ian Griffiths, policy director of the nonprofit Seamless Bay Area, a sponsor of the legislation. He pointed out that many state legislators want to boost transit ridership as a policy goal.

“There’s been a reluctance to acknowledge that having such a fragmented decision-making transit network doesn’t set us up for successs,” Griffiths said.

Chiu’s bill does not include a financing mechanism, but it coincides with the Faster Bay Area campaign for a sales tax to raise $100 billion for transportation funding over 40 years.

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