Editing Loading gauge (section)

====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>