BART’s approval rating hit a record low as riders bemoan crime and filth on the system, saying it’s become a de facto shelter for transients and a laboratory of societal problems.

A new survey of 5,292 customers, which goes before the Board of Directors on Thursday, shows that customer satisfaction plunged to 56 percent last year, from 69 percent three years ago. The drop occurred despite BART’s efforts to clean stations, repair old machinery and add glossy new train cars.

Since 2016, the Bay Area’s backbone rail system has declined in nearly every metric. Satisfaction with BART’s enforcement against fare cheats plummeted by nearly 20 percent. Feelings of personal security on the system dipped by 16 percent. Comfort with the police presence in BART stations went down nearly 15 percent.

It took years for BART’s negative image to build up and ossify, and now it’s going to be hard to shed, said board President Bevan Dufty.

“We’re doing the right things, I’m absolutely confident of it,” he said. “It’s just that negative experiences linger for a long time.”

The bad ratings come amid big political changes at BART. Its board has three new directors, including Mark Foley of Antioch, who beat a 24-year incumbent after running a fix-it campaign that emphasized BART’s many shortcomings.

Board directors will discuss the survey when they meet later this week for a two-day intensive workshop. The theme is to get on a correction course for 2027, by which point BART officials expect to have a new fleet of Bombardier trains operating, as well as new tracks and train controls.

“All of these things are going to make BART a world-class system again,” Dufty said, referring to the space-age railway that enthralled President Richard Nixon when he test-rode BART in 1972.

Decades later, public confidence in the system has eroded. A 2014 survey showed that 74 percent of riders were content with BART service, a number that slid to 69 percent two years later, before hitting last year’s slump to 56 percent.

And customers have peeled away from the system as crime and social issues welled up. Ridership plateaued at about 440,000 passengers a day in 2016 — BART’s all-time high after years of steady growth. It’s now hovering just above 425,000.

While 35 percent of people who ride BART less often say they’ve moved to a new home or office, others say they’re repelled by the transit system’s squalid or unsafe conditions. Twenty-seven percent said BART is too dirty, 23 percent cited concerns about crime, and 21 percent said the trains are too crowded.

“These numbers are bad, there’s no sugarcoating it,” said board Director Janice Li, whose district spreads through San Francisco. Her advice: Prioritize changes that get people excited, like the new Bombardier cars.

“Customer satisfaction about the new trains is absurdly high,” Li said.

BART has introduced a handful of new cars, but the rollout has been slow.

Agency officials announced an aggressive series of improvements last year, including elevator attendants in downtown San Francisco, beefed up police patrols inside Civic Center and Powell Street stations and colorful signs encouraging good behavior.

In May the agency opened a long-anticipated station in Antioch, and in October it quadrupled power washings at the two Mission street stops.

Earlier this month, the transit agency partnered with Contra Costa County to send a new homeless outreach team to end-of-the-line stations in Richmond, Pittsburg/Bay Point or Antioch. During their first week, the workers steered six people into shelters and six into warming centers.

Such investments became necessary as the in-your-face signs of poverty and regional homelessness began percolating into transit systems, said Armando Sandoval, crisis intervention training coordinator and community outreach liaison for the BART Police Department. He oversees the agency’s efforts to serve people who sleep on trains and seek shelter in stations.

“BART — it’s shelter, it’s safety,” Sandoval said in a recent interview, noting that people gravitate to the system because it meets “these very primal needs to survive.”

The agency spent $1.6 million on quality-of-life issues this year, splitting it among outreach teams, elevator attendants, street-level Pit Stop restrooms and extra security to deter people from camping on BART property.

And it’s seen results: BART’s transient count in the downtown San Francisco stations fell from 117 people in September 2017 to 85 people last month.

But that hasn’t stopped passengers from complaining.

Of 10 rider comments included in the survey, seven focused on homeless or mentally ill people, panhandlers and human waste. The three others called for more police patrols or other security measures.

BART officials pursued a far-reaching public safety campaign last summer, following the July fatal stabbing of 18-year-old Nia Wilson at Macarthur Station. In August, BART received a $6.8 million federal grant to keep a special police patrol on trains traveling through the busiest stations. The money will also pay for new radio equipment and surveillance cameras.

At least one rider noticed the difference.

“The increased police presence has improved the overall shocking quality of BART as of late,” said a commenter highlighted in the survey. “Please continue to increase security and enforce regulations!”

Other customers saw incremental progress in some aspects of the system. Noise ratings improved by 3.5 percent, a sign of success for ongoing wheel repair.

Approval of BART’s hours of operation shot up by 3 percent. And some riders took note of the transit agency’s new brightly colored website. It got a 2.9 percent ratings boost.

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

Twitter: @rachelswan