Vertical shaft

What a vertical shaft is

A vertical shaft is sunk straight down from the surface. Joined to a horizontal drift, the two together form the route of a watercourse or a tunnel.

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 shaft of about nine metres and a horizontal drift of about eleven running towards the Shonai river. The entry treats it as evidence of contemporary engineering practice.

Water gathered above the embankment drops nine metres down the shaft and then runs eleven metres horizontally to the river. Two lengths at right angles make one continuous channel.

The section is rectangular. Where railway tunnels were standardised on the Horseshoe section, a structure combining shaft and drift took its section from what excavation and construction required.

Reading the record

The two lengths are recorded separately. Adding them into a single figure loses the shape of the route, so the safer course is to keep the record's own phrasing of a nine-metre vertical length and an eleven-metre horizontal one.

From above the shaft reads as an opening; from the side it is a deep vertical space. The opening at ground level is small and gives little sense of the scale below, which is why the recorded dimensions matter.

Two written forms of the Japanese term exist, and the Agency for Cultural Affairs uses one of them. The same word appears in mining remains, where it names the route by which people and material were raised and lowered.