Rail boosters hope the newly formed Waterbury Rail Line Caucus will galvanize support for upgrades to the 27-mile rail line between the Brass City and Bridgeport. The group’s action plan includes new rail stations with amenities, a transfer station in Devon and a study into the possibility of extending the Waterbury line to Torrington. The state is set to complete a $90 million upgrade that includes new safety features and capacity improvements including passing sidings, Positive Train Control and signalization, by the end of 2021. Legislators say more trains are needed to realize the benefits of these upgrades, which cost closer to $120 million than the original estimate, said Rick Dunne, executive director of the Naugatuck Valley Council of Governments.