Complex sentence: The Greenbush Line is a planned branch of the MBTA commuter rail, running 18 miles from Boston, Massachusetts through the towns of Braintree, Weymouth, Hingham, Cohasset, and Scituate on the south shore of Massachusetts.
Split into simpler sentences: The Greenbush Line is a planned branch of the MBTA commuter rail. It is to run 18 miles from Boston, Massachusetts through the towns of Braintree, Weymouth, Hingham, Cohasset, and Scituate on the south shore of Massachusetts.