Culvert

What a culvert is

A culvert is a covered watercourse carried beneath an embankment or a road. What distinguishes it in Japanese is the covering: an open channel carries a different name.

On railways the need arises wherever a line is carried on made ground across a stream. The former Chuo Line Kasaishibora culvert in Aichi Prefecture, built in 1900 and repaired in 1957, is described as a brick culvert made to take stream water out from under an embankment, rectangular in section, formed by a Vertical shaft of about nine metres meeting a horizontal drift of about eleven towards the Shonai river. The entry values it as evidence of the engineering of its day.

Scale varies with the job. The former Hokuriku Line Wanayamadani culvert in Fukui Prefecture, from about 1896, is described as cut some twenty metres below track level, 46 metres long and three wide, steeply graded, with dressed stone side walls and Tunnel portal and a brick arch, and is called the longest culvert on the line.

Japanese records use the loanword for culvert alongside the native term, treating the two as the same thing.

More than one way to build one

The structure is not fixed. The Iga Railway Oda Second culvert in Mie Prefecture, built in 1916, is described as 8.0 metres long and 1.8 metres in both width and height, in farmland south-west of Iga-Ueno station, carrying the track on twenty-three granite beams about thirty centimetres square laid across stone abutments, an arrangement the entry calls unusual. It still serves as a city road.

Sections differ too. Kasaishibora is rectangular and Wanayamadani is arched. Where tunnels were standardised on the Horseshoe section, culverts took their shape from the ground and the water they had to carry.

On site, look at the base of an embankment. A small opening cut through where a line or road crosses a watercourse, with a channel behind it, is a culvert. On abandoned railways some have been converted into public roads.