An adit is a feature of a mine, which most people would refer to incorrectly as a ‘mineshaft’. It is a horizontal or near horizontal entrance to a mine. Within the mine, horizontal passages are known as ‘levels’ and an adit is a category of level that opens into the outside world. Adits can be used for the passage of road vehicles and/or railway rolling stock.
The use of adits for the removal of ore/drainage is more effective than shafts as their (near) horizontal nature makes for easier transport than hoisting material up a shaft.
Adits can vary in size, dependant on what was being transported through them. ‘Old mens workings’ or mines created before the advent of mechanisation, tend to be very small as only humans/animals passed through whereas for mining using modern trucks, adits can be quite large.