Caroline Casey was one of 21 people arrested at a sit-in at the State Transportation building in June while advocating for a $10-a-month youth T pass for people age 12 to 21.

The activists were protesting the Transportation Department’s lack of action on a youth pass pilot program, which they say Transportation Secretary Richard Davey promised them in 2011. MassDOT is currently facing budgetary constraints, but Casey says there are ways to fund the pilot program without draining the agency’s pockets.

Interviewed after a recent MassDOT meeting, Casey says the current $26 monthly student T pass is unaffordable for most Boston teens. In some cases, she says, students miss school or don’t receive health care because they cannot afford transportation. The T recently raised all fares except those for the current student pass and RIDE, which provides door-to-door transport for the disabled.

At 23, Casey describes herself as “adult support” for the teen-led Youth Affordabili(T) Coalition. Though no minors were arrested at the sit-in, Casey is adamant the coalition is a youth-led movement.

“I’m not a decision-maker,” she says, adding that the decision to hold the sit-in came from a group of teens between the ages of 15 and 18. She says the coalition’s rallies and protests typically draw hundreds of young people.

Casey is adamant that the protests are building support for the pass. She even saw evidence of that growing support while being arrested at the sit-in. The police officer who arrested her told her the city needed it, she says.