Complex sentence: SP gained full control of the Salem, Falls City and Western in 1912 and built what was then known as the Salem, Falls City & Western Railway Bridge or Union Street Railroad Bridge to connect the line to the Valley Main Line in 1913 at Lemrock.
Split into simpler sentences: SP gained full control of the Salem, Falls City and Western in 1912. SP built what was then known as the Salem, Falls City & Western Railway Bridge or Union Street Railroad Bridge to connect the line to the Valley Main Line in 1913 at Lemrock.