 The bridge was first proposed as part of the Cambrian Line between Aberystwyth and Pwllheli by the Aberystwyth and Welsh Coast Railway around 1861 - 2 . It was designed by Benjamin Piercy and Henry Conybeare in 1864 , and opened on 10 October 1867 . Conybeare decided to construct the viaduct from timber as it would be cheaper to import by sea than iron . As built , it included a wooden lifting drawbridge section at the northern end to permit the passage of tall ships . It was never in regular use since the opening of the railway killed off competition from boat traffic . In 1899 , the drawbridge arrangement was changed to the current swing bridge arrangement . It is still theoretically in operation , though it has not been opened since 1987 as part of a test operation . 
