AS A SAX-PLAYING busker in Suburban Station ad-libbed his final bars, stores shuttered for the night Tuesday and two homeless-outreach workers scanned the underground concourse.

The workers' goal: Get any people out on the streets - or those hiding out in Suburban Station to avoid the bone-chilling cold - into a shelter. The wind chill was projected to dip to a dangerous 5 degrees.

"This is one of our busiest nights," said Stanley Crawley. "It's going to be Code Blue all week."

The National Weather Service projects that every night this week, the temperature will dip below the 20-degree threshold that triggers a Code Blue, which means that advocates for the homeless switch from outreach about services to strongly urging people on the streets to get inside.

Crawley partnered with his former outreach trainer, Jonathan Evans, working for the Mental Health Association's outreach program, which collaborates with Project HOME and Horizon House to help people find shelter when winter arrives.

Evans started working with the MHA 21 years ago, when he was homeless. He's remained with the program ever since he turned his life around.

"I don't want to do anything else," he said, "I like to be a foot soldier to give people encouragement and some hope that their life can change 'cause my life has changed.

"I see myself as candlelight for people down the tunnel to let them know things can happen," he added.

On a typical night, Crawley and Evans canvass spots where the down-and-out and mentally ill linger; the two pass out information about shelter locations and medical services, including at 30th Street and Suburban stations.

On Tuesday, they persuaded a handful of people to enter shelters.

Jazzi Rogers, who is originally from West Philly but now homeless, had previously met the pair after the temperature first started to drop this winter. She was about to return to a shelter where she's staying when she saw them at Suburban Station and chatted with them, asking how they spent Christmas.

"These guys will go to the wire for you," Rogers said. "They will try to get you off the street and into somewhere. They're the good guys."