The driver shortage in San Francisco’s bus and rail system is nearly twice as bad as officials claimed during a crippling summer slowdown, according to a report released Wednesday.

The city’s budget and legislative analyst revealed the new number during a tense Board of Supervisors hearing to determine reasons for the driver deficit, which has caused delays and overcrowding. While San Francisco Municipal Transportation Agency chief Ed Reiskin focused on the difficulty of recruiting and training employees, Muni operators pointed to low pay and dangerous working conditions that chase people out of the job.

“If I were looking for a job today, I wouldn’t come to Muni,” said cable car operator Greg Ellis. “It’s dangerous, the pay is no good and if there’s a fight on the bus, you’re expected to intervene. Then you’re disciplined for intervening.”

SFMTA currently has 1,894 full-time drivers available on a given day — 411 fewer than the 2,305 it needs to deliver service, the new report said. That shortfall is more than twice what former transit Director John Haley reported over the summer, when he said the agency needed 159 operators to be fully staffed — a number that jumped to 245 during a troubled retrofit of the Twin Peaks Tunnel.

“What we’re concluding from the numbers is that the agency isn’t as attractive of a place to work as it has been in the past,” said director of policy analysis Fred Brousseau, presenting the report to the supervisors’ Government Audit and Oversight Committee. It took into account the 663 drivers who are absent on a given day because of vacation, jury duty, injuries or sick leave, which might explain the discrepancy; Haley’s figure referred strictly to the number of drivers Muni needs to run all its buses on an average day, said SFMTA spokesman Paul Rose.

The report showed that thin staffing on a bus or rail line has real-life repercussions. The effects were most severe in July and August, when Muni had to run shuttles around the closed Twin Peaks Tunnel. During that period Muni’s popular 38-Geary line missed 4,004 hours of service, while the 8-Bayshore missed 4,907 hours.

Reiskin said Muni is grappling with a competitive job market and that officials have struggled to stream employees through many levels of training. Those challenges were compounded during the Twin Peaks Tunnel closure, which happened just as the agency was overhauling its light-rail fleet, introducing a new fare box and radio system and adding new 40-foot trolleys.

But operators painted a more searing picture of the work environment at Muni, where hourly wages start at $22.70, and the take-home pay of a new union employee is $36,826 a year. It’s too low to qualify for affordable housing in San Francisco, so some drivers sleep in their cars outside the bus yards, said Roger Marenco, president of the Transit Workers Union.

Others drive in from as far away as Patterson (Stanislaus County), Merced or Stockton, where home prices are cheaper. Some work two or three jobs to make ends meet, including side gigs driving for Uber, Marenco said.

Employees at Muni also described painful experiences at work, including sexual assault and abuse from passengers who started fights or threw feces. The wage issue in particular stirred Supervisor Vallie Brown, who had called the hearing to grill Muni on its delays during the tunnel shutdown.

“It just started because I’m a transit rider, and I was pissed that the bus wasn’t there on time — so I walked,” Brown said.

The budget and legislative analyst’s report laid out several possible solutions to beef up hiring at Muni, including a free City College class to help eligible employees pass the driving permit test. It also suggested a wage increase to more accurately reflect the cost of living in the Bay Area.

And it recommended that SFMTA gather feedback from other transit unions throughout the country. The decline in applications for bus and rail drivers appears to be a nationwide trend, Brousseau said.

Since the Board of Supervisors does not have authority over San Francisco’s transportation systems, all of these proposals are merely suggestions, Brousseau said. Brown called for the discussion to resume in six months, following contract negotiations between the SFMTA and its union.

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

Twitter: @rachelswan