The Greenfield-based Franklin Regional Transit Authority says going fare-free on fixed bus routes has increased ridership, reduced tense interactions between passengers and drivers, and helped riders save money. As Athol Daily News reported, those are results U.S. Sen. Ed Markey and U.S. Rep. Ayanna Pressley are citing as they push a proposed $5 billion federal transit program. Here's what to know Greenfield's Franklin Regional Transit Authority…