Their heroic deeds have won them huge recognition this year – but don't expect them to toot their own horns.
"We pretty much spring into action," added driver Karen Martinez-Casper.
Martinez-Casper was driving her usual route early one morning when she spotted a 5-year-old boy standing on his own.
"He had no shoes, no coat," she recalled. "He was just shivering. I said, 'Are you OK?' I picked him up and walked as fast as I could."
Surveillance footage filmed by a camera aboard her bus shows her bringing him on board to warm him up. She called for help.
"I was truly blessed to help this little boy," she said.
Martinez-Casper, who helped the child in October 2017, was honored at a Milwaukee Bucks game in January.
Another bus driver, Diana Serrano, came to the rescue of a 2-year-old girl who had wandered away from home wearing just a diaper and T-shirt in August.
"She got out of the house. Everyone was sleeping," Serrano said. "She was scared. She couldn't find her mom."
In the incident, which was caught on camera, a good Samaritan handed the child to Serrano, who carried her to the bus and called 911. While they waited for authorities, Serrano showed the little girl puppy photos on her phone.
When her panicked mom emerged from a nearby home about 10 minutes later, she was relieved to see her daughter in safe hands.
"She was very grateful," Serrano said.
In another emergency, driver Michelle Mixon saw a woman collapse in front of her bus. The woman's 6-year-old daughter started screaming, "My mommy! My mommy!"
She ran to the bus and told Mixon her mom had suffered a seizure.
"Just watching that video made me cry," Mixon later told Inside Edition.
Mixon called paramedics to the scene while comforting the hysterical girl. She carried her to the ambulance, reassuring her that her mom was OK.
“They’re going to take care of her,” Mixon, a mother and grandmother who has driven for Milwaukee County Transit for 21 years, told the child.
Mixon said the incident, which unfolded in January 2018, was the "most memorable and emotional thing" she'd ever been through, the transit authority said at the time.