To cross a stream, street or valley (wherever the hold off because of a flight of locks at possibly side would be unacceptable) the valley is often spanned by a navigable aqueduct – a well-known case in point in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Environment https://damienmcknq.dailyhitblog.com/42562668/musica-infantil-for-dummies