This is a column about BART’s approval ratings bottoming out, kind of like your patience when you learn there’s a 20-minute delay.

But first, a story.

On Christmas Day, I got on a train at Rockridge Station. I walked to the other end of the car and saw an older man with a shaggy white beard sitting in a seat reserved for the elderly and disabled. He had a dirt-caked blanket draped over his legs, a mangled walker in front of him. He rubbed his forehead as he swayed. His lips moved, but nothing audible came out.

As I watched him, I caught a whiff — it was like opening the lid of a garbage can with week-old used diapers in it. Then I noticed the brownish fluid streaming on the floor underneath his seat. At MacArthur Station, people stepped over the liquid like they were hopping rain puddles.

“You’re disgusting,” one man shouted before pulling his sweater over his nose.

Several people walked past the man, crinkling their noses. What did I do? I did the same as everyone else I saw pass the ailing man: not a damn thing.

I didn’t want to call BART police and unintentionally criminalize his situation. What if he resisted?

When calling police, “You need to specifically say that someone needs a welfare check,” Alicia Trost, a BART spokeswoman, told me. “And that’s the perfect case of a welfare check.”

BART can’t do anything for a simple hygiene complaint. A caller would have to be more descriptive. In my case, Trost said I would’ve had to tell police dispatch that there were bodily fluids that needed to be cleaned.

“If you just say there’s a homeless person or someone who appears to be homeless, they smell and they’re sleeping and they have a blanket and a walker, that is not enough,” Trost said. “We cannot send an officer. This person is not breaking any laws.”

That person needed help.

A lot of the Bay Area’s homeless problems trickle down to BART, and that’s a problem for the transit agency, which now also has to do social work. As my colleague Rachel Swan wrote last month, BART’s approval rating hit a record low. Customer satisfaction plunged to 56 percent last year, from 69 percent three years ago.

In the survey of 5,292 customers, riders complained of crime and filth on the system, which they believe has become a dumping ground on wheels for transients. Twenty-seven percent of respondents said BART is too dirty. Mark Foley, a newly elected BART board director, wasn’t surprised by the survey results.

“That is exactly the experience I have had in the 26 years that I’ve commuted using BART,” he told me. “I very clearly saw the decline in the system over the decades.”

Foley, a systems analyst for East Bay Municipal Utility District, is a daily BART rider, commuting from Antioch to 12th Street/Oakland City Center Station. In November, Foley defeated Joel Keller, a 24-year incumbent, by emphasizing BART’s shortcomings. Now it’s up to him to fix the problems like the one I experienced.

“I think part of the way you have to do that is you’ve got to have some resources dedicated to at least trying to connect those individuals to the resources that will help support them,” Foley said. “It really makes no sense to approach it solely from an enforcement perspective.”

BART spent $1.6 million on quality-of-life issues in the fiscal year budget that runs through June 30, splitting it among homeless outreach teams, elevator attendants and street-level restrooms. That’s a start, but if BART wants its approval ratings to rise, it has to do more.

A homeless outreach team began working in Contra Costa County on Jan. 7. The team works from 11 p.m. to 7 a.m., helping BART clear trains of people at the end-of-the-line stations — and then preventing the same people from hopping on the first train in the morning. The crew rotates among stations in Richmond, Pittsburg/Bay Point and Antioch, and in its first two weeks the team referred 24 people to social services. There needs to be a dedicated crew at each station.

A second San Francisco homeless outreach team starts this month, and for next year’s budget BART is requesting money for homeless outreach teams in San Mateo and Alameda counties.

Bevan Dufty, BART’s board president, is advocating for an ambassador program, similar to the Muni Transit Assistance Program, which has trained workers in conflict resolution to ride specific routes.

“From the public standpoint, just a physical presence in the stations and on the trains ... I think would be huge,” he said.

I enjoy riding BART, because it’s one of the few places to truly experience the Bay Area’s diversity. BART is where low-income and wealthy people stand or sit alike with heads bent staring at phones. BART is a fashion show runway that’s sometimes also a performance theater for dancers and unscripted reality shows.

The “Oscar Grant” stickers recently placed over Fruitvale Station on train maps were artful. Still, every time I get on BART I think about Grant, who was fatally shot by a BART police officer a decade ago at Fruitvale Station. I also think about Nia Wilson, who was fatally stabbed at MacArthur Station in July.

Now I also think about the man I didn’t know how to help.

San Francisco Chronicle columnist Otis R. Taylor Jr. appears Mondays and Thursdays. Email: otaylor@sfchronicle.com Twitter: @otisrtaylorjr