Editing Loading gauge (section)

{{Short description|Maximum dimensions for railway vehicles and their loads}}
{{Use dmy dates|date=January 2020}}
{{train topics}}
[[File:Why London Underground is nicknamed The Tube.jpg|thumb|right|The [[Engineering tolerance|clearance space]] between a train and the tunnel is often small. Pictured is a [[London Underground]] [[Northern line]] [[London Underground 1995 Stock|1995 Stock]] train emerging from the tunnel north of [[Hendon Central tube station|Hendon Central station]].]]

A '''loading gauge''' is a diagram or physical structure that defines the maximum height and width dimensions in [[Rail transport|railway]] [[Rolling stock|vehicles]] and their loads. Their purpose is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and structures.<ref>{{Cite web |work= NetworkRail.co uk |url= http://www.networkrail.co.uk/aspx/2232.aspx |title= Glossary |publisher= Network Rail |access-date= 15 May 2009 |url-status=live |archive-url= https://web.archive.org/web/20090506214752/http://www.networkrail.co.uk/aspx/2232.aspx |archive-date=6 May 2009 }}</ref> Classification systems vary between different countries, and loading gauges may vary across a network, even if the [[track gauge]] is uniform.

The term loading gauge can also be applied to the maximum size of road [[vehicle]]s in relation to [[tunnel]]s, [[overpass]]es and [[bridge]]s, and [[Garage door|doors]] into [[automobile repair shop]]s, [[bus garage]]s, [[filling station]]s, [[Garage (residential)|residential garages]], [[multi-storey car park]]s and [[warehouse]]s.

A related but separate gauge is the [[structure gauge]], which sets limits to the extent that bridges, tunnels and other infrastructure can encroach on rail vehicles. The difference between these two gauges is called the [[Engineering tolerance#Clearance (civil engineering)|clearance]]. The specified amount of clearance makes allowance for [[Envelope (motion)|wobbling]] of rail vehicles at speed.