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 being upgraded in 2014.]]
File:DSC01964 enge Kurve Am Bangert.jpg)]]
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, tunnels and bridges, and the width of the doors that allow access to a warehouse from a rail siding. Specifications may include the minimum distance from rail vehicles to railway platforms, buildings, lineside electrical equipment cabinets, signalling equipment, third rails or supports for overhead lines.{{Cite web|url=http://www.railsystem.net/structure-gauge-and-kinematic-envelope/|title=Structure Gauge and Kinematic Envelope }}
A related but separate gauge is the loading gauge: a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. The difference between these two gauges is called the clearance. The specified amount of clearance makes allowance for 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 tunnels, the space beneath overpasses and the space within the superstructure of bridges, as well as doors into automobile repair shops, bus garages, filling stations, residential garages, multi-storey car parks, overhangs at drive-throughs and warehouses.{{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 sag curves, bridge deflection and expected settlements with a recommendation of minimum clearance of {{convert|5|m|ftin}}.{{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}}
In UK, the "standard minimum clearance" for structures over public highways is {{Convert|16|ft|6|in|m}}.{{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}} In United States, the "minimum vertical clearance" of overpasses on Interstate Highway System is {{convert|16|ft|m}}.{{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}}
Gallery
Image:Gabarit-ferroviaire.svg|{{center|1=Structure gauge for a bridge or other wayside objects
hauteur libre = clear height
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}}
See also
{{Div col}}
- Air draft, applies to bridges across navigable waterways
- Berne gauge
- Bridge
- Bridge strike
- Clearance car
- Cut
- Disadvantages of third rail (additional infrastructure restrictions)
- Engineering tolerance
- List of bridges known for strikes
- Loading gauge
- Railway platform
- Railway platform height
- Tunnel
- Wayobjects
{{div col end}}
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}}
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