View source for Structure gauge

{{Short description|Minimum clearance, height and width of railway infrastructure}}
{{train topics}}
[[File:2014 Replacement of New Road Bridge, Milton Ernest, Bedfordshire.png|thumb|left|Increasing the structure gauge for a larger loading gauge can involve substantial work. The UK's [[Midland Main Line]] being upgraded in 2014.]]
[[File:DSC01964 enge Kurve Am Bangert.jpg|thumb|left|In narrow curves, long cars like this {{cvt|26.4|m|ftin}} long express train car protrude further into the gauge than on a straight track. (180° curve near [[Königstein im Taunus]])]]

A '''structure gauge''', also called the '''minimum structure outline''', is a diagram or physical structure that sets limits to the extent that bridges, tunnels and other infrastructure can encroach on rail vehicles. It specifies the height and width of station platforms, [[tunnel]]s and [[bridge]]s, and the width of the doors that allow access to a [[warehouse]] from a [[Siding (rail)|rail siding]].  Specifications may include the minimum distance from rail vehicles to [[railway platform]]s, buildings, lineside electrical equipment cabinets, [[railway signal|signalling]] equipment, [[third rail]]s or supports for [[overhead line]]s.<ref>{{Cite web|url=http://www.railsystem.net/structure-gauge-and-kinematic-envelope/|title=Structure Gauge and Kinematic Envelope }}</ref>

A related but separate gauge is the [[loading gauge]]: a diagram or physical structure that defines the maximum height and width dimensions in [[Rail transport|railway]] vehicles and their loads. The difference between these two gauges is called the [[Clearance (civil engineering)|clearance]]. The specified amount of clearance makes allowance for [[Envelope (motion)|wobbling]] of rail vehicles at speed or the shifting of vehicles on curves; consequently, in some circumstances a train may be permitted to go past a restricted clearance at very slow speed.
	
== Road traffic application ==
{{Main|Clearance (civil engineering)#Vertical clearance}}
The term can also be applied to the minimum size of road [[tunnel]]s, the space beneath [[overpass]]es and the space within the [[superstructure]] of [[bridge]]s, as well as [[Garage door|doors]] into [[automobile repair shop]]s, [[bus garage]]s, [[filling station]]s, [[Garage (residential)|residential garages]], [[multi-storey car park]]s, [[Overhang (architecture)|overhangs]] at [[drive-through]]s and [[warehouse]]s.{{cn|date=August 2023}}{{clear|left}}

[[Eurocode 1: Actions on structures]] has a definition of "physical clearance" between roadway surface and the underside of bridge element. The code also defines the clearance that is shorter than the physical clearance to account for [[Geometric design of roads|sag curves]], bridge [[Deflection (engineering)|deflection]] and expected settlements with a recommendation of minimum clearance of {{convert|5|m|ftin}}.<ref>{{cite book |title=Eurocode 1 - Actions on structures - Part 1-7: General actions - Accidental actions |date=July 2006 |publisher=The European Union |url=https://www.phd.eng.br/wp-content/uploads/2015/12/en.1991.1.7.2006.pdf |access-date=31 August 2023}}</ref> 
In UK, the "standard minimum clearance" for structures over public highways is {{Convert|16|ft|6|in|m}}.<ref>{{cite book |title=Preventing of Strikes on Bridge Over Highways - A Protocol for Highway Managers & Bridge Owners |publisher=Network Rail on behalf of Bridge Strike Prevention Group |page=6 |edition=2 |url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/350114/network-rail-bridge-strike-protocol.pdf |access-date=29 August 2023}}</ref> In United States, the "minimum vertical clearance" of overpasses on [[Interstate Highway System]] is {{convert|16|ft|m}}.<ref>{{cite web |title=Right of Passage: The Controversy Over Vertical Clearance on the Interstate System |url=https://www.fhwa.dot.gov/infrastructure/50vertical.cfm |publisher=U.S. Department of Transportation Federal Highway Administration |access-date=27 August 2023}}</ref>

== Gallery ==
<gallery mode="packed" heights="200px" caption="Structure gauges">
Image:Gabarit-ferroviaire.svg|{{center|1=Structure gauge for a [[bridge]] or other [[Wayobjects|wayside objects]]<br>hauteur libre = clear height<br>Niveau superieur des rails = Top of rails}}
File:Lichtraumprofil.svg|{{center|German structure gauge showing (left side) limits to encroachment of the rail vehicle envelope on mainlines and (right side) secondary tracks}}
</gallery>

==See also==
{{Div col}}
* [[Air draft]], applies to [[bridge]]s across [[Navigability|navigable]] [[waterway]]s
* [[Berne gauge]]
* [[Bridge]]
* [[Bridge strike]]
* [[Clearance car]]
* [[Cut (earthmoving)|Cut]]
* [[Third rail#Safety|Disadvantages of third rail]] (additional infrastructure restrictions)
* [[Engineering tolerance#Clearance (civil engineering)|Engineering tolerance]]
* [[List of bridges known for strikes]]
* [[Loading gauge]]
* [[Railway platform]]
* [[Railway platform height]]
* [[Tunnel]]
* [[Wayobjects]]
{{div col end}}

==References==
<references />

== External links ==
* [https://tc.canada.ca/en/rail-transportation/standards/standards-respecting-railway-clearance Transport Canada, Standard Respecting Railway Clearance]
* [https://web.archive.org/web/20100707185308/http://www.rica.org/displaycommon.cfm?an=1&subarticlenbr=8 GLOSSARY OF TERMS USED IN RAILROAD HIGH AND WIDE CLEARANCES] 
* [https://books.google.com/books?id=AK9LAAAAYAAJ&q=Railway+Line+Clearances Railway line clearances and car dimensions including weight ..., Volumes 87-90]
* [http://www.ipm.fraunhofer.de/railway www.ipm.fraunhofer.de/railway]

{{Rail tracks}}

{{DEFAULTSORT:Structure Gauge}}
[[Category:Rail infrastructure]]
[[Category:Road hazards]]


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