also: どうどう
service tunnel; utility tunnel
Technical term for an underground tunnel housing utility lines such as cables, gas pipes, or water mains. Primarily used in civil engineering and infrastructure contexts.
High-voltage cables are laid in this service tunnel.
There is a plan to house gas pipes inside the utility tunnel.
Standard kanji form for this technical term.
Alternate reading; less common than とうどう.
Compound of 洞 (tunnel, cave) and 道 (path, road). The reading とうどう is the standard on'yomi combination; どうどう is a less common variant reading.