Editing USRA standard

{{More citations needed|date=December 2021}}[[File:USRA_Light_Mikado.jpg|thumb|The [[USRA Light Mikado|Light Mikado]] was the standard light freight locomotive and the most widely built type of the USRA standard designs.]]
The '''USRA standard''' [[locomotive]]s and [[railroad car]]s were designed by the [[United States Railroad Administration]], the [[nationalised|nationalized]] rail system of the [[United States]] during [[World War I]].  1,870 [[steam locomotive]]s and over 100,000 railroad cars were built to these designs during the USRA's tenure. The locomotive designs in particular were the nearest the American [[railroad]]s and [[List of locomotive builders|locomotive builders]] ever got to standard locomotive types, and after the USRA was dissolved in 1920 many of the designs were duplicated in number, 3,251 copies being constructed overall.  The last steam locomotive built for a [[Class I railroad]] in the United States, an [[0-8-0]] built by the [[Norfolk and Western Railway]] in 1953, was a USRA design.  A total of 97 railroads used USRA or USRA-derived locomotives.

==Steam locomotive types==
The USRA developed designs for [[0-6-0]] and [[0-8-0]] [[switcher locomotive]]s, [[2-6-6-2]] and [[2-8-8-2]] [[Mallet locomotive]]s, and both light and heavy versions of the [[2-8-2]], [[2-10-2]], [[4-6-2]], and [[4-8-2]] types.  The light versions were designed with an [[axle load]] of 54,000&nbsp;lb (24,500&nbsp;kg) permitting usage on the vast majority of railroads, while the heavy versions were designed to a maximum axle load of 60,000&nbsp;lb (27,200&nbsp;kg) for lines with more heavily constructed track.

The U.S.R.A. also distributed [[Russian locomotive class Ye|2-10-0 Decapods of Russian design]] to railroads under its control.

===USRA 0-6-0===
255 of the [[USRA 0-6-0]] design were built, as well as many copies.

===USRA 0-8-0===
175 of the [[USRA 0-8-0]] design were built, and it was copied extensively thereafter.

===USRA Light 2-8-2 "Mikado"===
614 of the [[USRA Light Mikado]] type were constructed, making it the most populous USRA type.

===USRA Heavy 2-8-2 "Mikado"===
233 of the [[USRA Heavy Mikado]]s were built.

===USRA Light 2-10-2 "Santa Fe"===
94 [[USRA Light Santa Fe]] locomotives were constructed.

===USRA Heavy 2-10-2 "Santa Fe"===
175 [[USRA Heavy Santa Fe]] locomotives were built.

===USRA Light 4-6-2 "Pacific"===
106 [[USRA Light Pacific]]s were constructed.

===USRA Heavy 4-6-2 "Pacific"===
20 [[USRA Heavy Pacific]]s were built.

===USRA Light 4-8-2 "Mountain"===
47 of the [[USRA Light Mountain]] type were built.

===USRA Heavy 4-8-2 "Mountain"===
15 [[USRA Heavy Mountain]]s were constructed.

===2-6-6-2===
30 of the [[USRA 2-6-6-2]] type were built.

===2-8-8-2===
106 of the [[USRA 2-8-8-2]] locomotives were constructed.  The [[Norfolk and Western Railway]], in particular, continued building this type after the USRA period, developing and modernising it over time, as its Class Y.  A N&W Y6B was the last conventional freight-hauling steam locomotive built in the United States.

==Freight cars==
As part of the USRA, two common [[boxcar]] designs were developed:  a single sheathed car and a double sheathed car.  When the USRA boxcars were being designed there wasn't an industry consensus on which was better, so both were built.  Freight car design was still in flux in the early part of the 20th century.  As John White points out in ''The American Freight Car'', most cars were really composites, not completely [[wood]] or [[steel]], and even after steel cars had become the norm, wood had its uses and advantages.  Still, steel [[underframe]]s had come to replace wood underframes, but as [[metallurgy]] improved, there were new designs developed that took advantage of the improved technology.  USRA double sheathed boxcars had a fishbelly underframe while the USRA single sheathed cars did not.  
In general, double sheathed boxcars are like [[girder bridge]]s, so all the support needs to come from the frame.  Those cars need a stronger frame, hence the fishbelly underframe.   Single sheathed cars are like [[truss bridge]]s, with the metal side bracing acting as the main structural support for the "bridge."  While some engineers did not trust the steel bracing to support a single sheathed car and ordered fishbelly frames for strength, others valued the savings in weight and ordered cars with simpler frames like the USRA SS design.
{| class="wikitable"
|+Type of cars built by the USRA<ref>{{Cite web|date=2015-10-01|title=USRA Freight Car Assignments|url=http://designbuildop.hansmanns.org/usra-freight-car-assignments/|access-date=2020-08-11|website=Notes on Designing, Building, and Operating Model Railroads|language=en-US}}</ref>
!Type
!USRA Specification
!Number of cars produced
|-
|50-ton Single-Sheathed Box Car
|1001-B 
|25,000
|-
|50-ton Drop-Bottom [[Gondola (rail)|Gondola]]
|1002-B
|20,000
|-
|40-ton Double-Sheathed Box Car
|1003-B
|25,000
|-
|55-ton Steel Twin [[Hopper car|Hopper]]
|1005-B
|5,000
|-
|70-ton Steel Drop-End Mill Gondola
|1006-B
|5,000
|}

== References ==
{{Reflist}}

{{commons category|USRA locomotives}}
{{USRA locomotives}}
{{Woodrow Wilson}}

{{DEFAULTSORT:Usra Standard}}
[[Category:USRA locomotives| ]]
[[Category:Rolling stock of the United States]]
[[Category:Locomotive designs used by multiple railways]]