The train passengers leaving Union Station jostle about, squeezing by one another with plates stacked high with tamales, taquitos and buffalo wings. Headed toward San Bernardino on a Metrolink train, they hustle in the compressed space, grabbing another slice of pizza or a bit of smoked salmon. They talk of sports and shout over conversations to pass another soda.

At the center of the party is Lucy Reinhardt-Ulatowski, doling out egg rolls, homemade broccoli salad and sandwiches, which she spent hours making the night before.

When Reinhardt-Ulatowski began commuting by Metrolink in 2001 -- a five-hour round trip from Victorville to downtown Los Angeles -- she worried it would be painfully monotonous. On her first few trips, she stared out at the passing landscape of foothills, warehouses and housing tracts as her fellow commuters read, typed on their laptops and listened to music.

"It was kind of scary, all by yourself," she said, "trying to look cool."

But over time, she began chatting with the people on her car, conversations that evolved into relationships. Today, the friendships she forged during those long commutes are stronger than those at work or in her suburban subdivision.

She and her train friends organize potluck parties aboard the trains, vacation together and socialize off the tracks. And when one member of the extended family was seriously injured in a bicycle accident last year, Reinhardt-Ulatowski held a fundraiser to help him out.

Reinhardt-Ulatowski is part of what transit experts say is a small but remarkable subculture that has developed inside Southern California's commuter trains. What starts as a smile and a nod unfolds into in-depth discussions of football and families.

Metrolink, which operates the region's commuter trains, has at least three rail cars in its network in which groups have organized. The "party trains" are the exception, with most Metrolink riders using their commute for decidedly more solitary pursuits, such as reading, paying bills or working on their laptop computers.

Train officials and others are intrigued by how these groups form and the lasting bonds of these commuter friendships.

"People tend to sit in the same place every day, and as they see each other again and again, they start talking," Metrolink spokeswoman Sharon Gavin said. "It's a way to de-stress about your day before you get home. By the time you get home, you don't really have to complain to your family."

The groups formed spontaneously without any help from Metrolink, but "it's something that we encourage," Gavin said. "Get to know your fellow riders. It adds a level of humanness to the commute."

Club cars where commuters socialize have long been a part of the East Coast train culture, but it's something new to Southern California.

Anastasia Loukaitou-Sideris, chairwoman of the department of urban planning at the University of California at Los Angeles, said the groups "attest to the fact that a mode of transportation like a train is much more of a social mode than a car. When you are in a train, you have to interact with other people."

That is something Sheila Fisher and other passengers on the Metrolink between Los Angeles and Orange County discovered.

When she first began her daily travels from Los Angeles to Orange County eight years ago, Fisher was still mourning the death of her husband. Sitting alone on the train, she would watch from afar as a boisterous group laughed and chatted every afternoon on the ride home. It made her feel lonelier.

One afternoon, the whole group came over.

"They said, 'Why don't you come and join us? We'd like to know who you are,' " Fisher recalled. "For me, it was like a reawakening. I met more people than I ever had before."

Since then, Fisher, 61, who lives in Los Angeles but works as a collections manager for the Orange County Credit Union, has become one of the group's main party organizers.

She hosted 10 people from her train for a weekend getaway to Rosarito Beach, Mexico, and held several parties on the train. But the group is now doing more than socializing.

Fisher and others have volunteered together at the Los Angeles Police Museum and for a nonprofit medical clinic.

"We've helped people write resumes, helped people prepare for interviews, we've mentored people," Fisher said. "If someone is going to be out of a job, we network."

Until last year, the friendships on Reinhardt-Ulatowski's train were casual -- confined to potlucks and occasional vacations.

Then, one of her fellow commuters, Mike Yanez, was critically injured when a car struck his bicycle. He was unconscious for 16 days. Doctors put plates in his cheeks, reconstructed his eyebrows, pulled out his jaw and fixed his nose.

The dog groomer also required knee surgery.

News of the accident traveled fast on the train. Yanez stood out because he often lugged his bike aboard.

"The more we found out about him and how badly he'd been hurt," Reinhardt-Ulatowski said, "the more we wanted to do something for him."

She started a collection to send a get-well card. Then she and other riders held a raffle onboard, and with the money raised, they bought him a new bike and helmet.

They surprised Yanez with the bike when he returned to the train

"I was touched. . . . Not everybody does stuff like that," he said.

Valient Phipps, left, talks with Lucy Reinhardt-Ulatowski aboard the Metrolink train about an upcoming party on the train.