Complex sentence: The Nassau Street Line was completed on May 30,1931, and a fourth service pattern was added-the Nassau Street Loop; trains could enter Manhattan along the south bridge tracks or through the tunnel and return via the other.
Split into simpler sentences: The Nassau Street Line was completed on May 30,1931, and a fourth service pattern was added: the Nassau Street Loop. Trains could enter Manhattan along the south bridge tracks or through the tunnel and return via the other.