TAUNTON — For the first time in more than a half century, on Monday, residents of Massachusetts’ South Coast communities, including Fall River and New Bedford, began hopping on a commuter rail train to be whisked directly into Boston.

Like all other Commuter Rail trips, the first train Monday morning on the MBTA’s new Fall River/New Bedford line set off with a jolt. But unlike the rest, it was followed by an unfamiliar sound for the early hour: applause.