PHILADELPHIA — Commuters biked, walked, juggled carpool schedules and hitched rides as the city’s transit system ground to a near halt for a second day Wednesday, a rush worsened when a regional rail train caught fire.

Regional rail lines are running because their workers are represented by a different union. But trouble hit around 7 a.m. when a car caught fire as it headed downtown, causing delays and confusion. Southeastern Pennsylvania Transportation Authority officials said it was likely an electrical fire and was not suspicious.

More than 5,000 members of SEPTA’s largest union walked off the job early Tuesday, leaving thousands of people struggling for ways to get around without the use of subways, trolleys or buses.

“I can’t take the whole strike off,” said Niki LaGrone, 27, a Catholic school teacher in North Philadelphia, as she prepared to take regional rail as far as it goes and then walk a mile and a half to school. “I’m going to have to show up. ... Hopefully, I can find somebody when I get in to work to help me out.”

The Philadelphia school district reported a 16 percent drop in high school attendance Wednesday. On an average weekday, about 54,000 public and parochial students take SEPTA to school.

At the J.R. Masterman high school, Robin Carpenter unloaded a bicycle from his father’s car so he could make the 7-mile ride home in the afternoon.

“I do ride my bike sometimes but not during cross-country season,” he said, adding that the strike was an inconvenience. “It’s too tiring.”

Karen Pollack scrambled to find ways to get her 16- and 13-year-old daughters to and from their respective schools.

Pollack lives in the city’s Germantown section and left about 15 minutes earlier to drop off her younger daughter at Masterman. Her husband dropped off their older daughter at a school about 5 miles from home.

Getting them home could be a challenge, though, since her older daughter usually takes SEPTA. Now, she’s going to walk the 15 or so blocks to her sister’s school and hopefully find a spot in that car pool — if there’s room.

“It was a little stressful last night,” Pollack said. “It’s going to be day-to-day.”

Jim Jordan, an assistant general manager for SEPTA, said the regional rail car that caught fire was about 40 years old, one of many slated to be replaced soon. The origin of the blaze was probably in the heating or electrical system, Jordan said, and the entire fleet will be inspected once the cause is determined.

Flames could be seen shooting from the front of the train shortly after 7 a.m. A big cloud of smoke also billowed from the train. No injuries were reported, but hundreds of riders had to be evacuated.

Wayne Rafferty, 27, of Pottstown, a lab technician at Children’s Hospital of Philadelphia, said he had to calm down another passenger on the packed train, and he saw other passengers kicking out the removable emergency windows. Once outside the train, he took a picture of the front of it with flames and smoke.

“I already texted in the photos to my boss. I said, ‘This was my train,’” he said. “He said he’ll see me when he sees me, so I’m going to start making the hike.” Rafferty estimated that it would take about an hour to walk to his workplace.

The sudden strike by Transport Workers Union Local 234 has all but crippled the system, which averages more than 928,000 trips each weekday. The union walked away from negotiations on a new contract over disagreements on wage, pension and health care issues.

Union president Willie Brown said the main issue is pensions.

“My members stand strongly behind me,” Brown said a news conference Wednesday, adding that he hopes to meet with Gov. Ed Rendell in the next day or two. “Even though we did not want to strike, we were forced into a strike.”

SEPTA General Manager Joe Casey also said he planned to talk to Rendell.

Some riders said they weren’t feeling much compassion.

“I know I make less than they do, so I’m not that sympathetic right now,” LaGrone said.

Union workers, who earn an average of $52,000 a year, are seeking a 9 percent wage hike over four years, according to Jamie Horwitz, a union spokesman; they also want to keep the current 1 percent contribution they make toward the cost of health care coverage. Their contract expired in March.

SEPTA was offering an 11.5 percent wage increase over five years, with a $1,250 signing bonus in the first year, and increases in workers’ pensions, Maloney said. But Horwitz said the raises are less than that because of the proposed increase in pension contributions.

The strike also affects buses that serve the suburbs in Bucks, Montgomery and Chester counties.

A 2005 SEPTA strike lasted seven days, while a 1998 transit strike lasted for 40 days.

The strike forced some employers to scramble, too.

Cisco Navarro, 41, a part-time night clerk at the UPS distribution facility in South Philadelphia, got to work via a patchwork bus system that UPS set up by hiring bus companies.

His biggest challenge, he said, was getting the buses to stop. Employees have to show company IDs to get on the bus, but drivers can’t tell who is a UPS employee from a distance — and sometimes, he said, they don’t stop.

“You’re waving your arms,” he said, adding that he has now borrowed a UPS hat. “I need to bring cheerleaders.”