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.

Service launched Monday on the MBTA's long-awaited South Coast Rail commuter line. For the first time in nearly seven decades, passengers can now take a train from Fall River to Boston. Sign up for our Newsletters“This is a really,