Two Metro Transit police officers approached a young woman who was spread across several seats while sleeping on an eastbound Green Line train one evening last month. A bulging plastic bag served as a makeshift pillow, and her coat was pulled defensively about her slight frame.

One officer gently tapped her snow boots.

"Are you OK?" he asked. "Do you have somewhere to go?"

"Trying to get home," the woman mumbled.

The officers shrugged, and soon stepped off the train bound for downtown St. Paul. The woman pushed herself up against the train's window and tugged her down coat over her face, seemingly invisible to the other passengers.

Each night, dozens of passengers sleep on Metro Transit trains and buses or in transit shelters. The number tends to swell during the grip of winter and as the wee hours of the night stretch on.

Sleeping on trains and buses is not illegal, and the vast majority of those who do so pay their fares, police say. Most of the "sleepers," as they're known, are homeless and seeking safe haven from the elements. The temperature on the Green and Blue light rail lines hovers at a comfortable 72 degrees.

No one seems to know how many people turn to transit for their shelter. Yet most of the 34 transit agencies surveyed last year by the federal Transportation Research Board described homeless riders as an issue of concern.

Transit police find themselves on the front lines of a vast, seemingly inextricable societal challenge, but with few resources and little training to combat it. They say making it illegal to sleep on transit won't solve the problem.

"You can't arrest your way out of this situation," said Sgt. Mario Ruberto, who leads Metro Transit's homeless efforts. "The jails don't want them, and the criminal justice system is not the right place [for them]."

Ruberto laments a dearth of affordable housing and space in local homeless shelters, as well as a shortage of mental health and substance abuse services.

"I think the public wants to be compassionate," Ruberto said. "If you have a solution, let us know," he added with a heavy sigh. "We'd win a Nobel Prize."

Public cubbyholes

As temperatures hovered around zero Tuesday night, Sgt. Erin Dietz of the Metro Transit police department directed her unmarked SUV to transit shelters and public "cubbyholes" where the homeless tend to sleep. When such stark temperatures strike, police leave the transit shelters open as a refuge for the homeless.

One man set up his sleeping bag at an indoor bus shelter on Fifth Street E. and Minnesota Street in St. Paul, using his roller suitcase as a pillow. He said he'd been "camping out" for several years and did not want to share his name. Many years ago, he said, he drove a cab for a living and boasted that he once ferried Walter Matthau to the St. Paul Hotel while the late actor was filming "Grumpy Old Men" in Minnesota.

"Did you know he's a devout Washington Redskins fan?" the former cabbie said. When asked if he was spending the night in the bus shelter, the man eyed the nearby police officers and said, "I'm just getting organized."

It's difficult to quantify a transient population. A study by Wilder Research, an arm of the St. Paul-based Amherst H. Wilder Foundation, found 9,312 people experiencing homelessness in Minnesota when a one-night count was taken in October 2015. But, as the report notes, the number underrepresents the state's total homeless population.

Put differently, an estimated 15,000 people were homeless on any given night in 2015 around the state. Overall, the figure has declined 9 percent between 2012 and 2015, following a jump of 32 percent between 2006 and 2012 — a period that includes the Great Recession.

Two-thirds of homeless adults tallied in the Twin Cities were using transit, and 47 percent opted for light rail, according to Wilder Research. It's unknown how many of them turn to transit for shelter, or how often.

Many homeless people tend to congregate on the trains at night — after commuters have come and gone. The Green Line, which links the downtowns of Minneapolis and St. Paul, runs all night and has an average weekday ridership of 43,642. The older Blue Line, running from downtown Minneapolis to the Mall of America, sees an average of 30,767 each weekday.

Bob Wagner, who lives in St. Paul, rides both the Blue and Green lines to get to his job at the Mall of America.

"For the most part, [the sleepers] don't bother anyone," he said, noting he takes the train during off hours. "If they're completely racked out on a seat, who cares? Just find another seat."

Wagner says he's disabled and does not drive. "If it weren't for the train, I'd be unemployed," he said. "Nobody's sleeping on the train because they want to be."

Most sleepers keep to themselves. Recently, a reporter approached a dozing woman surrounded by plastic bags on the Blue Line. "I'm not doing interviews now," she said, before closing her eyes and drifting off.

Rethinking protocol

About four years ago, Ruberto crafted a new program that called for Metro Transit police to rethink its protocol for handling the homeless who sleep on trains and buses. Typically, they were taken to jail, or hospital emergency rooms if there was a health issue.

Or, police would issue a ticket, barring them from using transit for 30 days. But people would just get back on the train, only to be picked up for trespassing later.

"That starts an endless legal cycle," Ruberto said. "The mind-set was: 'We're cops, we arrest people.' "

Instead, Metro Transit police opted to partner with social service and nonprofit organizations such as St. Stephen's Human Services and Union Gospel Mission Twin Cities to match available services to those in need. Now, police often give sleepers toiletries, a blanket and a booklet detailing where to find help.

Ideally, Metro Transit would hire outreach workers to work with the homeless, but Ruberto says the agency's budget is stretched thin.

This approach appears to work in other cities nationwide, according to the Transportation Research Board (TRB). "Successful policies target behavior rather than groups or individuals," according to a TRB report. It noted that the homeless population is not homogenous and that social service groups and nonprofits have greater insight into their needs.

The report cautions that "transit agencies will never solve the problem of homelessness alone or even in partnership with others." Yet Ruberto, who spent 20 years as a paramedic for Hennepin County, remains optimistic.

Dislikes shelters

A week before Christmas, a woman who said her name was Rita sat aboard the Green Line train at Union Depot in St. Paul and prepared to take a nap as she waited for it to head west. She held tightly onto the backpack across her chest, and she pulled a roller suitcase and a luggage rack holding her belongings close.

She says she sleeps on the train because she dislikes staying in shelters. She's working with a social service group to get an apartment after losing her home in St. Paul in foreclosure several years ago following the death of her husband. She continues to work with an attorney to get her home back.

As Rita chats, an older man stumbles on the train at the Hennepin Avenue stop, clutching a tallboy beer. The can slips and beer sloshes on the floor of the train.

"Oh great, I have to sleep smelling that all night," Rita says good-naturedly. "Why couldn't he have spilled coffee? That smells nice."

The man sits down and stares blankly ahead. Pretty soon, he's sleeping, too.