Editing Loading gauge (section)

====Great Britain====
Great Britain has (in general) the most restrictive loading gauge (relative to track gauge) in the world. That is a legacy of the British railway network being the world's oldest, and of having been built by a large number of different private companies, each with different standards for the width and height of trains. After nationalisation, a standard static gauge W5 was defined in 1951 that would virtually fit everywhere in the network. The W6 gauge is a refinement of W5, and the W6a changed the lower body to accommodate third-rail electrification. While the upper body is rounded for W6a with a static curve, there is an additional small rectangular notch for W7 to accommodate the transport of {{convert|2.44|m|ftin|abbr=on}} ISO containers, and the W8 loading gauge has an even larger notch spanning outside of the curve to accommodate the transport of {{convert|2.6|m|ftin|abbr=on}} ISO containers. While W5 to W9 are based on a rounded roof structure, those for W10 to W12 define a flat line at the top and, instead of a strict static gauge for the wagons, their sizes are derived from dynamic gauge computations for rectangular freight containers.<ref name="britishgauging">{{cite web|url=http://www.rssb.co.uk/Library/groups-and-committees/2013-guide-vehicle-structure-sic-guide-to-british-gauging-t926.pdf|publisher=[[Rail Safety and Standards Board]] (RSSB)|date=January 2013|access-date=3 August 2015|url-status=dead|archive-url=https://web.archive.org/web/20151019001730/http://www.rssb.co.uk/Library/groups-and-committees/2013-guide-vehicle-structure-sic-guide-to-british-gauging-t926.pdf|archive-date=19 October 2015|title=Gauging - The V/S SIC Guide to British gauging practice}}</ref>

[[Network Rail]] uses a ''W'' loading gauge classification system of freight transport ranging from W6A (smallest) through W7, W8, W9, W9Plus, W10, W11 to W12 (largest). The definitions assume a common "lower sector structure gauge" with a common freight platform at {{convert|1100|mm|in|2|abbr=on}} above rail.<ref>{{cite web|url=http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/research/T727_rpt_final_part3.pdf|title=Freight Opportunities Stage 2 Part 3 – Available Space Assessment – ISO Container Routes|at=7481- LR- 009 issue 1|publisher=Rail and Safety Standards Board|date=September 2007|quote=(2 Definitions)'W' Gauge. A set of static gauges that defines the physical size of freight vehicles. [...] (3 Methodology) It was assumed that the container / wagon combinations under consideration already conform to the dimensions set out in the lower sector structure gauge. Therefore, only structural clearances above {{convert|1100|mm|in|2|abbr=on}} above rail level were assessed.|url-status=dead|archive-url=https://web.archive.org/web/20110927012222/http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/research/T727_rpt_final_part3.pdf|archive-date=27 September 2011}}</ref>

In addition, gauge C1 provides a specification for standard coach stock, gauge C3 for longer [[British Rail Mark 3|Mark 3]] coaching stock, gauge C4 for [[British Rail Class 390|Pendolino]] stock<ref>{{Cite web|url=https://www.rssb.co.uk/Library/groups-and-committees/2013-guide-vehicle-structure-sic-guide-to-british-gauging-t926.pdf|title=The V/S SIC Guide to British gauging practice|access-date=19 February 2018|publisher=Rail and Safety Standards Board|date=January 2013|quote=Mark 3 coaches are labeled C3 restriction and Class (Pendolino) trains are labeled C4. These do not refer to any standard gauge.|url-status=dead|archive-url=https://web.archive.org/web/20161019113126/http://www.rssb.co.uk/Library/groups-and-committees/2013-guide-vehicle-structure-sic-guide-to-british-gauging-t926.pdf|archive-date=19 October 2016}}</ref> and gauge UK1 for high-speed rail. There is also a gauge for locomotives. The size of container that can be conveyed depends both upon the size of the load that can be conveyed and the design of the rolling stock.<ref>{{Cite web|url=http://www.rgsonline.co.uk/Railway_Group_Standards/Infrastructure/Guidance%20Notes/GEGN8573%20Iss%202.pdf|title=GE/GN8573|access-date=15 May 2009|url-status=dead|archive-url=https://web.archive.org/web/20110929163219/http://www.rgsonline.co.uk/Railway_Group_Standards/Infrastructure/Guidance%20Notes/GEGN8573%20Iss%202.pdf|archive-date=29 September 2011}}</ref>

* W6A: Available over the majority of the British rail network.<ref>{{Cite web|url=http://www.networkrail.co.uk/documents/3150_2004BusinessPlanNetworkCapability.pdf|title=Business Plan 2004 – Network Capability|publisher=Network Rail|access-date=15 May 2009|url-status=dead|archive-url=https://web.archive.org/web/20120929221932/http://www.networkrail.co.uk/documents/3150_2004BusinessPlanNetworkCapability.pdf|archive-date=29 September 2012}}</ref>
* W8: Allows standard {{convert|2.6|m|ftin|abbr=on}} high [[shipping container]]s to be carried on standard wagons.<ref name=Felix>{{Cite web|url=http://www.dft.gov.uk/pgr/shippingports/ports/ir/felixstowesouth/felixstowesouthreconfigurati4953?page=34|title=Felixstowe South reconfiguration inspector's report, Strategic Rail Authority submission|publisher=Department for Transport|access-date=21 July 2017|url-status=bot: unknown|archive-url=http://webarchive.nationalarchives.gov.uk/20100210092126/http://www.dft.gov.uk/pgr/shippingports/ports/ir/felixstowesouth/felixstowesouthreconfigurati4953?page=34|archive-date=10 February 2010}}</ref>
* W9: Allows {{convert|2.9|m|ftin|abbr=on}} high [[Intermodal container|''Hi-Cube'']] shipping containers to be carried on "[[Megafret]]"<ref>{{cite web|url=http://www.ersrail.com/files/file/SFFGGMRRSS-ME-PB.pdf|title=Megafret|website=ersrail.com|url-status=dead|archive-url=https://web.archive.org/web/20150705172157/http://www.ersrail.com/files/file/SFFGGMRRSS-ME-PB.pdf|archive-date=5 July 2015|access-date=22 November 2012}}</ref> wagons that have lower deck height with reduced capacity.<ref name=Felix/> At {{convert|2.6|m|ftin|abbr=on}} wide, it allows for {{convert|2.5|m|ftin|abbr=on}} wide ''Euro'' shipping containers,<ref name=For>{{Cite web|url=http://www.freightonrail.org.uk/HotTopicsTenProposedEnhancementsScotland.htm|title=TEN PROPOSED ENHANCEMENT SCHEMES IN SCOTLAND|publisher=Freight on rail|access-date=17 May 2009|url-status=dead|archive-url=https://web.archive.org/web/20081118194205/http://www.freightonrail.org.uk/HotTopicsTenProposedEnhancementsScotland.htm|archive-date=18 November 2008}}</ref> which are designed to carry Euro-[[pallet]]s efficiently<ref name=MS/><ref>{{Cite web|url=http://www.containercontainer.com/about_containers.aspx|title=Standard Shipping Containers|publisher=Container container|access-date=18 May 2009|url-status=live|archive-url=https://web.archive.org/web/20090707132234/http://www.containercontainer.com/about_containers.aspx|archive-date=7 July 2009}}</ref>
* W10: Allows {{convert|2.9|m|ftin|abbr=on}} high ''Hi-Cube'' shipping containers to be carried on standard wagons<ref name=Felix/> and also allows {{convert|2.5|m|ftin|abbr=on}} wide ''Euro'' shipping containers.<ref name=For/> Larger than UIC A.<ref name=MS/>
* W11: Little used but larger than UIC B.{{Citation needed|date=November 2021}}
* W12: Slightly wider than W10 at {{convert|2.6|m|ftin|abbr=on}} to accommodate refrigerated containers.<ref>{{Cite web|url=http://www.central-railway.co.uk/resources/cr_FreightConsultation2006.pdf|title=24 November 2006 Freight RUS Consultation Response National RUS|publisher=Central Railways|access-date=17 May 2009|url-status=dead|archive-url=https://web.archive.org/web/20080807135513/http://www.central-railway.co.uk/resources/cr_FreightConsultation2006.pdf|archive-date=7 August 2008}}</ref> Recommended clearance for new structures, such as bridges and tunnels.<ref name=RUS>{{Cite web|url=http://www.networkrail.co.uk/browse%20documents/rus%20documents/route%20utilisation%20strategies/freight/freight%20rus.pdf|title=Freight RUS|url-status=dead|archive-url=https://web.archive.org/web/20120302212305/http://www.networkrail.co.uk/browse%20documents/rus%20documents/route%20utilisation%20strategies/freight/freight%20rus.pdf|archive-date=2 March 2012|access-date=16 May 2009}}</ref>
* UIC GC: [[Channel Tunnel]] and [[Channel Tunnel Rail Link]] to London; with proposals to upgrade the [[Midland Main Line]] northwards from London to GB+ standards.<ref name=DfTlong>{{Cite web|url=http://www.dft.gov.uk/pgr/rail/strategyfinance/strategy/freightnetwork/|title=Strategic Freight Network: The Longer-Term Vision|publisher=Department for Transport|access-date=17 May 2009 |url-status=dead |archive-url=http://webarchive.nationalarchives.gov.uk/20110504024713/http://www.dft.gov.uk/pgr/rail/strategyfinance/strategy/freightnetwork/ |archive-date=4 May 2011 }}</ref>

A strategy was adopted in 2004 to guide enhancements of loading gauges<ref>{{Cite web|url=http://www.dft.gov.uk/press/releases/sra/2004/2004b/ragaugingpolicyaimstomak1394.pdf|archive-url=https://web.archive.org/web/20090512055126/http://www.dft.gov.uk/press/releases/sra/2004/2004b/ragaugingpolicyaimstomak1394.pdf|url-status=dead|archive-date=12 May 2009|title=New SRA Gauging Policy Aims to Make Best Use of Network Capability|publisher=Department for Transport|access-date=15 May 2009}}</ref> and in 2007 the [[freight route utilisation strategy]] was published. That identified a number of key routes where the loading gauge should be cleared to W10 standard and, where structures are being renewed, that W12 is the preferred standard.<ref name="RUS" />

Height and width of containers that can be carried on GB gauges (height by width). Units as per source material.
* W9: {{convert|9|ft|0|in|m|abbr=on}} by {{convert|2.6|m|ftin|abbr=on|order=flip}}
* W10: {{convert|9|ft|6|in|m|abbr=on}} by {{convert|2.5|m|ftin|abbr=on|order=flip}}
* W11: {{convert|9|ft|6|in|m|abbr=on}} by {{convert|2.55|m|ftin|abbr=on|order=flip}}
* W12: {{convert|9|ft|6|in|m|abbr=on}} by {{convert|2.6|m|ftin|abbr=on|order=flip}}<ref name="For" />

=====Tube lines=====
* [[City and South London Railway]] was built with tunnels of only {{convert|10.5|ft|m|2|abbr=on}} diameter. Enlarged for [[Northern line]] to {{convert|12.0|ft|m|2|abbr=on}}
* [[Central line (London Underground)|Central line]] with tunnels of {{convert|11|ft|8+1/4|in|m|2|abbr=on}}, increased on curves, reduced to {{convert|11|ft|6|in|m|2|abbr=on}} near to stations. This makes Central line trains unique on the [[London Underground]] system because, although the loading gauge of the rolling stock is the same as the other 'tube' lines, the smaller size of the tunnel requires that the positive [[Fourth rail|conductor]] rail is {{convert|1.6|in|abbr=on}} higher than on all other lines.

A Parliamentary committee headed by [[James Stansfeld]] then reported on 23 May 1892, "The evidence submitted to the Committee on the question of the diameter of the underground tubes containing the railways has been distinctly in favour of a minimum diameter of {{convert|11|ft|6|in|abbr=on}}". After that, all tube lines were at least that size.<ref>{{cite magazine |magazine=Railway Magazine |date=February 1959 |pages=94–96 |first1=Michael |last1=Robbins |title=The Size of the Tube }}</ref>

* [[Piccadilly line]] with tunnels of {{convert|12|ft|m|2|abbr=on}}
* [[Victoria line]] with tunnels of {{convert|12.5|ft|m|2|abbr=on}}; enlarged to reduce air friction.
* [[Glasgow Subway]] with tunnels of {{convert|11|ft|m|2|abbr=on}} and a unique track gauge of only {{Track gauge|4ft|lk=on}}.
* [[Tyne and Wear Metro]] with tunnels of {{convert|15.5|ft|m|2|abbr=on}}; built to mainline rail network standards.