Complex sentence: Arcadia Press, p75 South Acton served station stop for both the Fitchburg Branch of the B&M and Marlborough Branch Railroad, which split off from the Fitchburg Railroad after the station.
Split into simpler sentences: Arcadia Press, p75 South Acton served as a station stop for both the Fitchburg Branch and Marlborough Branch of the B&M. The Marlborough Branch split off from the Fitchburg Railroad after the station.