Editing Loading gauge (section)

===North America===

====Freight====
{{Further|Boxcar#Loading gauges}}
{{Further|Double-stack rail transport#Sizes and clearances}}

The American loading gauge for [[Railroad car#Freight cars|freight cars]] on the [[North American rail network]] is generally based on standards set by the [[Association of American Railroads]] (AAR) Mechanical Division.<ref name="gauge">{{cite book |title=Car and Locomotive Cyclopedia of American Practice |edition=1970 |publisher=Association of American Railroads Mechanical Division |date=1970 |oclc=5245643 |pages=71–74 }}</ref> The most widespread standards are '''''AAR Plate B''''' and '''''AAR Plate C''''',<ref name="gauge2">[https://my.aar.org/OTLR/Documents/Section%201/Section1AppendixA_20200826.pdf Preload Inspection Checklist and Equipment Plate Diagrams] {{webarchive|url=https://web.archive.org/web/20210224215901/https://my.aar.org/OTLR/Documents/Section%201/Section1AppendixA_20200826.pdf|date=February 24, 2021}}</ref> but higher loading gauges have been introduced on major routes outside urban centers to accommodate rolling stock that makes better economic use of the network, such as [[Auto rack|auto carriers]], [[Boxcar#Hicube boxcar|hi-cube boxcars]], and [[Double-stack rail transport|double-stack container loads]].<ref>{{Cite web|url=http://www.csx.com/index.cfm/customers/other-services-partners/dimensionalclearance/clearance-maps/|archive-url=https://web.archive.org/web/20121210165904/http://www.csx.com/index.cfm/customers/other-services-partners/dimensionalclearance/clearance-maps/|url-status=dead|title=Clearance maps for CSX, a typical major carrier|archive-date=10 December 2012}}</ref> The maximum width of {{cvt|10|ft|8|in}} on {{cvt|41|ft|3|in}} ('''AAR Plate B'''), {{cvt|46|ft|3|in}} ('''AAR Plate C''') and all other [[Bogie|truck]] centers (of all other '''AAR Plates''') are on a {{cvt|441|ft|8+3/8|in|m|2}} radius or [[Degree of curvature#Length selection|13°]] curve.<ref name="gauge" /><ref name="gauge2" /> In all cases of the increase of truck centers, the decrease of width is covered by '''AAR Plates D1 and D2'''.<ref name="gauge" /><ref name="gauge2" />

Listed here are the maximum heights and widths for cars. However, the specification in each AAR plate shows a car cross section that is chamfered at the top and bottom, meaning that a compliant car is not permitted to fill an entire rectangle of the maximum height and width.<ref name="gauge2" />

{| class="wikitable"
! rowspan="2" | AAR<br>Plate !! colspan="2"| Width !! colspan="2" | Height !! colspan="2" | Truck centers !!rowspan="2" width=350| Comments !! rowspan="2" | Image
|- 
! width=50|ft in !!width=40|m !! width=50|ft in !!width=40| m !!width=50| ft in !!width=40| m  
|-
| '''B''' || {{convert|10|ft|8|in|m|2|disp=table}} || {{convert|15|ft|1|in|m|2|disp=table}} || {{convert|41|ft|3|in|m|2|disp=table}} || For longer truck centers, the width is decreased according to [[Graph of a function|graph]] '''AAR Plate B-1''' on a {{cvt|441|ft|8+3/8|in|m|2}} radius curve<ref name="gauge" /> or '''AAR Plate D1'''<ref name="gauge2" /> || [[File:Gabarit AAR Plate-B.png|100px|center]]
|-
| '''C''' || {{convert|10|ft|8|in|m|2|disp=table}} || {{convert|15|ft|6|in|m|2|disp=table}} || with {{convert|46|ft|3|in|m|2|disp=table}} || For longer truck centers, the width is decreased according to graph '''AAR Plate C-1''' on a {{cvt|441|ft|8+3/8|in|m|2}} radius curve<ref name="gauge" /> or '''AAR Plate D1'''<ref name="gauge2" /> || [[File:Gabarit AAR Plate-C.png|100px|center]]
|-
| '''E''' || {{convert|10|ft|8|in|m|2|disp=table}} || {{convert|15|ft|9|in|m|2|disp=table}} || with {{convert|46|ft|3|in|m|2|disp=table}}
|| However the top of rail clearance is {{convert|2+3/4|in|mm|0|abbr=on}} instead of {{convert|2+1/2|in|mm|0|abbr=on}}.<ref name="gauge2" /><ref name="gauge3">{{cite book |title=Car and Locomotive Cyclopedia of American Practice |edition=1984 |publisher=Association of American Railroads Mechanical Division |date=1984 |oclc=5245643 |pages=91, 92 }}</ref> || [[File:Gabarit AAR Plate E.png|100px|center]]
|-
| '''F''' || {{convert|10|ft|8|in|m|2|disp=table}} || {{convert|17|ft|0|in|m|2|disp=table}} ||with {{convert|46|ft|3|in|m|2|disp=table}} || As with '''AAR Plate C''' but {{convert|18|in|mm|0|abbr=on}} taller than '''AAR Plate C''' and {{convert|15|in|mm|0|abbr=on}} taller than '''AAR Plate E''', and the car cross section is larger at the top than '''AAR Plate E'''.<ref name="gauge2" /> || [[File:Gabarit AAR Plate F.png|100px|center]]
|-
|rowspan="2" |'''H''' || {{convert|10|ft|8|in|m|2|disp=table}}<ref name="Guide"/>||  {{convert|20|ft|3|in|m|2|disp=table}} ||{{convert|62|ft|7|in|m|2||disp=table}}<ref name="Guide"/> ||e.g. Including the height of [[Intermodal container|double stacked containers]] in [[well car]]s. The cross section at the bottom of the well car differs from the X section of all other AAR plates. X section at center of car<ref name="gauge2" /><ref>April 2001 [[Official Railway Equipment Register]] {{cite web |title=Archived copy |url=http://www.railresource.com/content/wp-content/uploads/2010/06/orerrr_126_1_sample.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130509020851/http://www.railresource.com/content/wp-content/uploads/2010/06/orerrr_126_1_sample.pdf |archive-date=9 May 2013 |access-date=23 November 2012}} {{cite web |title=Archived copy |url=http://www.uprr.com/customers/attachments/rule16.pdf |url-status=dead |archive-url=https://web.archive.org/web/20100401022710/http://www.uprr.com/customers/attachments/rule16.pdf |archive-date=1 April 2010 |access-date=23 November 2012}}</ref><ref name="Guide">{{Cite web|url=http://worldtraderef.com/WTR_site/Rail_Cars/Guide_to_Rail_Cars.asp|title=Guide to Railcars|date=31 October 2011|archive-url=https://web.archive.org/web/20111031040725/http://worldtraderef.com/WTR_site/Rail_Cars/Guide_to_Rail_Cars.asp |archive-date=31 October 2011 }}</ref> Width of {{convert|10|ft|8|in|m|2}} only possible at the [[Bogie|trucks]]<ref name="gauge2" /> || [[File:Gabarit AAR Plate-H.png|100px|center]]
|-
|{{convert|10|ft|1|in|m|2|disp=table}}<ref name="gauge2"/>  ||  {{convert|20|ft|3|in|m|2|disp=table}} ||{{convert|63|ft|9|in|m|2||disp=table}} ||e.g. Including the height of [[Intermodal container|double stacked containers]] in [[well car]]s. The width at greater than {{cvt|63|ft|9|in|m|2}} covered by ''' AAR Plate D1'''<br />The cross section at the bottom of the well car differs from all other AAR Plates.<ref name="gauge2" /><ref>April 2001 Official Railway Equipment Register {{cite web |url=http://www.railresource.com/content/wp-content/uploads/2010/06/orerrr_126_1_sample.pdf |title=Archived copy |access-date=23 November 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130509020851/http://www.railresource.com/content/wp-content/uploads/2010/06/orerrr_126_1_sample.pdf |archive-date=9 May 2013 }} {{cite web |url=http://www.uprr.com/customers/attachments/rule16.pdf |title=Archived copy |access-date=23 November 2012 |url-status=dead |archive-url=https://web.archive.org/web/20100401022710/http://www.uprr.com/customers/attachments/rule16.pdf |archive-date=1 April 2010 }}</ref> in well cars<ref name="Guide" />|| [[File:Gabarit AAR Plate-H.png|100px|center]]
|-
|rowspan="2" | '''---''' ||{{convert|9|ft|10.25|in|m|2|disp=table}}<ref name="Guide"/>|| {{convert|3|ft|11|in|m|2|disp=table}}<ref name="Guide"/>||{{convert|66|ft|0|in|m|2|disp=table}}<ref name="Guide"/> || rowspan="2" | e.g. {{convert|85|ft|2+1/2|in|m|2|adj=on}}<ref name="Guide"/> long [[flatcar]]s, *Height of deck at center of car<ref name="Guide" /> Width covered by  '''AAR Plate D1'''.<ref name="gauge2" />||rowspan="2" | 
|-
| {{convert|9|ft|1|in|m|2|disp=table}}<ref name="Guide"/>  
|-
| '''J'''|| {{convert|10|ft|8|in|m|2|disp=table}} ||{{convert|19|ft|0|in|m|2|disp=table}} ||{{convert|55|ft|0|in|m|2|disp=table}} || Truck centers can be more. Widths covered by  '''AAR Plate D1'''.<ref name="gauge2" />||
|-
| '''K''' || {{convert|10|ft|0|in|m|2|disp=table}}  || {{convert|20|ft|3|in|m|2|disp=table}}<ref name="gauge2" /> || {{convert|65|ft|0|in|m|2|disp=table}}||e.g. [[Autorack]] (road vehicles on trains).  Width at center of car covered by  '''AAR Plate D1'''<ref name="gauge2" /><ref name="Guide"/><ref name="autorack">{{Cite web|url=http://www.gbrx.com/PDFtecbulletins/GenFreightAutoMax.pdf|title=Autorack}}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><!-- <ref name="Guide.1">{{Cite web |url=http://worldtraderef.com/WTR_site/Rail_Cars/Guide_to_Rail_Cars.asp |title=Guide to Railcars |access-date=26 March 2011 |archive-date=31 October 2011 |archive-url=https://web.archive.org/web/20111031040725/https:// |url-status=dead }}</ref> -->||
|-
| '''L''' || {{convert|10|ft|8|in|m|2|disp=table}}||{{convert|16|ft|3|in|m|2|disp=table}} ||{{convert|46|ft|3|in|m|2|disp=table}} || For locomotives only<ref name="gauge2" /> ||
|-
| '''M''' || {{convert|10|ft|8|in|m|2|disp=table}}||{{convert|16|ft|3|in|m|2|disp=table}} ||{{convert|46|ft|3|in|m|2|disp=table}} || For locomotives only <ref name="gauge2" />|| 
|}

Technically, AAR Plate B is still the maximum height and truck center combination<ref name="gauge" /><ref name="gauge2" /> and the circulation of AAR Plate C is somewhat restricted. The prevalence of excess-height rolling stock, at first ~{{convert|18|ft|m|2|abbr=on}} [[Piggyback (transportation)#Rail|piggybacks]] and [[Boxcar#Hicube boxcar|hicube boxcars]], then later [[autorack]]s, airplane-parts cars, and flatcars for hauling [[Boeing 737]] fuselages, as well as {{convert|20|ft|3|in|m|2|abbr=on}} high double-stacked [[Intermodal container|containers]] in [[Well car|container well cars]], has been increasing. This means that most, if not all, lines are now designed for a higher loading gauge. The width of these extra-height cars is covered by '''AAR Plate D1'''.<ref name="gauge" /><ref name="gauge2" />

All the Class I rail companies have invested in longterm projects to increase clearances to allow double stack freight. The mainline North American rail networks of the Union Pacific, the BNSF, the Canadian National, and the Canadian Pacific, have already been upgraded to '''AAR Plate K'''. This represents over 60% of the Class I rail network.<ref>{{cite journal |title=Railway Line Clearances and Car Dimensions including Weight Limitations of Railroads in the United States, Canada, Mexico and Cuba |journal=Railway Line Clearances and Car Dimensions Including Weight Limitations of Railroads in the United States, Canada, Mexico and Cuba.|oclc = 10709088}}</ref>

===== Gallery =====
<gallery mode="packed" hrights="140"px">
File:Boeing 737 fuselage train hull 3473.jpg|[[Boeing 737 Next Generation]] [[fuselage]] being transported by rail on a [[flatcar]]
File:DTTX 724681 20050529 IL Rochelle.jpg|[[Double-stack rail transport|Double-stack container service]] requires the highest loading gauge in common use in North America.
File:ETTX 905721 20050529 IL Rochelle.jpg|A Norfolk Southern autorack on a [[TTX Company|TTX]] flatcar also requires the highest loading gauge in common use in North America.
File:Santa_Fe_TOFC_(Trailer_on_Flat_Car)_(10589289363).jpg|A [[Atchison, Topeka and Santa Fe Railway|Santa Fe]] [[semi-trailer]] carried on a flatcar as part of a [[Trailer-on-flatcar|TOFC]] train.
</gallery>

==== Passenger service ====
[[File:Gabarit AAR passager.png|thumb|Standard AAR passenger loading gauge (does not accommodate Amtrak "Superliners" nor ex-AT&SF "Hi-Level" cars)]]

The old standard North American [[passenger car (rail)|passenger railcar]] is {{convert|10|ft|6|in|m|2|abbr=on}} wide by {{convert|14|ft|6|in|m|2|abbr=on}} high and measures {{convert|85|ft|0|in|m|2|abbr=on}} [[Headstock (rolling stock)#Length over headstocks|over coupler pulling faces]] with {{convert|59|ft|6|in|m|2|abbr=on}} [[Bogie|truck]] centers, or {{convert|86|ft|0|in|m|2|abbr=on}} over coupler pulling faces with {{convert|60|ft|0|in|m|2|abbr=on}} truck centers. In the 1940s and 1950s, the American passenger car loading gauge was increased to a {{convert|16|ft|6|in|m|2|abbr=on}} height throughout most of the country outside the Northeast, to accommodate [[dome car]]s and later [[Superliner (railcar)|Superliner]]s and other [[Bilevel rail car|bilevel]] commuter trains. Bilevel and Hi-level passenger cars have been in use since the 1950s, and new passenger equipment with a height of {{convert|19|ft|9+1/2|in|m|2|abbr=on}} has been built for use in Alaska and the Canadian Rockies. The [[structure gauge]] of the [[Mount Royal Tunnel]] used to limit the height of bilevel cars to {{convert|14|ft|6|in|m|2}} before it was permanently closed to interchange rail traffic prior to its conversion for the [[Réseau express métropolitain|REM]] rapid transit system.{{Citation needed|date=November 2021}}

==== New York City Subway ====
The [[New York City Subway]] is an amalgamation of three former constituent companies, and while all are [[standard gauge]], inconsistencies in loading gauge prevent cars from the former [[Brooklyn–Manhattan Transit Corporation|BMT]] and [[Independent Subway System|IND]] systems ([[B Division (New York City Subway)|B Division]]) from running on the lines of the former [[Interborough Rapid Transit Company|IRT]] system ([[A Division (New York City Subway)|A Division]]), and vice versa. This is mainly because IRT tunnels and stations are approximately {{convert|1|ft|mm|0}} narrower than the others, meaning that IRT cars running on the BMT or IND lines would have [[platform gap]]s of over {{convert|8|in|mm|0}} between the train and some platforms, whereas BMT and IND cars would not even fit into an IRT station without hitting the platform edge. Taking this into account, all maintenance vehicles are built to IRT loading gauge so that they can be operated over the entire network, and employees are responsible for [[mind the gap|minding the gap]].

Another inconsistency is the maximum permissible railcar length. Cars in the former IRT system are {{convert|51|ft|m|2}} {{as of|2013|12|lc=y}}. Railcars in the former BMT and IND can be longer: on the former [[Rapid transit operations of the BRT and BMT#Divisions|Eastern Division]], the cars are limited to {{convert|60|ft|m|2}}, while on the rest of the BMT and IND lines plus the [[Staten Island Railway]] (which uses modified IND stock) the cars may be as long as {{convert|75|ft|m|2}}.<ref>{{cite web |title=NYC Fun Facts: Not All NYC Subway Trains Are the Same Size |url=https://untappedcities.com/2017/08/02/nyc-fun-facts-subway-tracks-have-different-widths-in-nyc/ |website=Untapped Cities |access-date=11 July 2018 |date=2 August 2017}}</ref><ref>[[Second Avenue Subway]] [http://web.mta.info/capital/sas_docs/sdeis.htm Draft Environmental Impact Statement], {{cite web|url= http://web.mta.info/capital/sas_docs/sdeis/glossary.pdf |title=Glossary }}&nbsp;{{small|(45.6&nbsp;[[Kibibyte|KiB]])}}</ref>

====Boston (MBTA)====
The [[Massachusetts Bay Transportation Authority]]'s (MBTA) rapid transit system is composed of four unique subway lines; while all lines are standard gauge, inconsistencies in loading gauge, electrification, and platform height prevent trains on one line from being used on another. The first segment of the [[Green Line (MBTA)|Green Line]] (known as the [[Tremont Street subway]]) was constructed in 1897 to take the streetcars off [[Boston]]'s busy downtown streets. When the [[Blue Line (MBTA)|Blue Line]] opened in 1904, it only ran streetcar services; the line was converted to rapid transit in 1924 due to high passenger loads, but the tight clearances in the tunnel under the [[Boston Harbor]] required narrower and shorter rapid transit cars.<ref>{{cite book| last = Clarke| first = Bradley| title = The Boston Rapid Transit Album| publisher = Boston Street Railway Association| year = 1981| location = Cambridge, Mass.| page = 8}}</ref> The [[Orange Line (MBTA)|Orange Line]] was originally built in 1901 to accommodate heavy rail transit cars of higher capacity than streetcars. The [[Red Line (MBTA)|Red Line]] was opened in 1912, designed to handle what were for a time the largest underground transit cars in the world.<ref name=Fischler>{{cite book|last1=Fischler|first1=Stanley I.|title=Moving millions : an inside look at mass transit|date=1979|publisher=Harper & Row|location=New York|isbn=0-06-011272-7|edition=1st|url-access=registration|url=https://archive.org/details/movingmillions00stan}}</ref>{{rp|127}}

====Los Angeles (LACMTA)====
The [[Los Angeles Metro Rail]] system is an amalgamation of two former constituent companies, the [[Los Angeles County Transportation Commission]] and the Southern California Rapid Transit District; both of those companies were responsible for planning the initial system. It is composed of two heavy rail subway lines and several light rail lines with subway sections; while all lines are standard gauge, inconsistencies in electrification and loading gauge prohibit the light rail trains from operating on the heavy rail lines, and vice versa. The LACTC-planned [[A Line (Los Angeles Metro)|Blue Line]] was opened in 1990 and partially operates on the route of the [[Pacific Electric]] interurban railroad line between downtown Los Angeles and Long Beach, which used overhead electrification and street-running streetcar vehicles. The SCRTD-planned [[B Line (Los Angeles Metro)|Red Line]] (later split into the Red and [[D Line (Los Angeles Metro)|Purple]] lines) was opened in 1993 and was designed to handle high-capacity heavy rail transit cars that would operate underground. Shortly after the Red Line began operations, the LACTC and the SCRTD merged to form the [[Los Angeles County Metropolitan Transportation Authority|LACMTA]], which became responsible for planning and construction of the [[C Line (Los Angeles Metro)|Green]], [[L Line (Los Angeles Metro)|Gold]], [[E Line (Los Angeles Metro)|Expo]], and [[K Line (Los Angeles Metro)|K]] lines, as well as the [[D Line Extension]] and the [[Regional Connector]].