To cross a stream, street or valley (wherever the hold off because of a flight of locks at possibly facet can be unacceptable) the valley could be spanned by a navigable aqueduct – a popular instance in Wales may be the Pontcysyllte Aqueduct (now a UNESCO Planet Heritage Website) https://griffinxhmrv.jts-blog.com/36022168/considerations-to-know-about-urso-fofo