To cross a stream, street or valley (exactly where the delay due to a flight of locks at both side can be unacceptable) the valley is often spanned by a navigable aqueduct – a well known illustration in Wales may be the Pontcysyllte Aqueduct (now a UNESCO Environment Heritage https://troybauja.yomoblog.com/43960906/how-urso-fofo-can-save-you-time-stress-and-money