Complex sentence: The docks were always overshadowed by Bristol and Avonmouth docks, and the ordinary passenger service declined in the twentieth century, leading to closure to passengers in 1964, and to all traffic in 1981.
Split into simpler sentences: The docks were always overshadowed by Bristol and Avonmouth docks. The ordinary passenger service declined in the twentieth century, leading to closure to passengers in 1964, and to all traffic in 1981.