Editing Track gauge (section)

==Uses of the term==
The most common use of the term "track gauge" refers to the transverse distance between the inside surfaces of the two load-bearing rails of a [[railway track]], usually measured at {{convert|12.7|mm|in|abbr=off|comma=off|sigfig=2}} to {{convert|15.9|mm|in|abbr=off|comma=off|sigfig=2}} below the top of the rail head in order to clear worn corners and allow for rail heads having sloping sides.<ref>{{cite book |last=Tratman |first=E.E. Russell |date=1908 |title=Railway track and track work |publisher=The Engineering News Publishing Co. |edition=3rd |location=New York |page=383}}</ref> The term derives from the "gauge", a metal bar with a precisely positioned lug at each end that track crews use to ensure the actual distance between the rails lies within tolerances of a prescribed standard: on curves, for example, the spacing is wider than normal.<ref>{{cite book|last= Wilson |first= John |date= 2021 |title= The train to Oodna-Woop-Woop: a social history of the Afghan Express |location= Banksia Park, South Australia |publisher= Sarlines Railway Books |isbn= 9780646842844 |page=31 }}</ref> Deriving from the name of the bar, the distance between these rails is also referred to as the track gauge.<ref>{{cite book|title=Track Maintenance Guide |author=<!--Not stated-->|date=1988 |location=Adelaide |publisher=Australian National [Railways Commission] |section=Section 12.2 }}</ref>