The structure gauge, also called the minimum clearance outline, is the minimum height and width of tunnels and bridges as well as the minimum height and width of the doors that allow a rail siding access into a warehouse. In addition, the term may apply to the minimum distance to railway platforms (passenger or freight), buildings, electrical equipment boxes, railway signal equipment, third rails or to supports for overhead catenaries or overhead lines from the track.
The difference between the structure gauge and the loading gauge is called the "clearance".
The amount of clearance between the loading gauge and the structure gauge depends on the speed of the train, due to the train wobbling, so a train may be able to get past a restricted clearance by travelling at slow speed.
The term structure gauge can also be applied to the minimum size of road tunnels, road bridges etc.
Famous quotes containing the word structure:
“A structure becomes architectural, and not sculptural, when its elements no longer have their justification in nature.”
—Guillaume Apollinaire (1880–1918)