# Breather switch

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{{Short description|Gap in railway tracks}}
{{See also|Expansion joint}}

A '''breather switch''', '''expansion joint''', or '''adjustment switch''' is an intentional gap in [railway track](/source/railway_track)s to [allow for thermal expansion](/source/expansion_joint) in long sections of otherwise unbroken rail. They are placed between very long sections of [continuous welded rail](/source/Railway_track) or at the transition from continuous welded rail to jointed track, and commonly in the vicinity of bridges, [viaduct](/source/viaduct)s and tunnels where the infrastructure and track may expand at different rates.<ref>{{Cite web |last=Briginshaw |first=David |date=2016-03-08 |title=British university to build prototype switch |url=https://www.railjournal.com/track/british-university-to-build-prototype-switch/ |access-date=2023-02-13 |website=International Railway Journal |language=en-GB}}</ref>

The mating sections are tapered diagonally (unlike a [butt joint](/source/butt_joint) between two lengths of rail), allowing smoother transitions and higher speeds across the gap.<ref>{{Cite journal |last1=Kampczyk |first1=Arkadiusz |date=2020-08-10 |title=Measurement of the Geometric Center of a Turnout for the Safety of Railway Infrastructure Using MMS and Total Station |journal=Sensors |language=en |volume=20 |issue=16 |pages=4467 |doi=10.3390/s20164467 |issn=1424-8220 |pmc=7472250 |pmid=32785082 |doi-access=free |bibcode=2020Senso..20.4467K }}</ref>

Breather switches have two advantages over jointed track: they greatly reduce the small gap between the rails, eliminating or significantly reducing the noise and vibration caused by passing [train](/source/train)s, and, where continuous welded rail is particularly prone to expansion, they act as relief points to ensure that track does not warp out of shape or result in a [sun kink](/source/buckling).<ref>{{Cite web |last1=Hoather |first1=Ian |last2=Mandal |first2=Nirmal |date=May 2016 |title=Management of Rail Stress in a Modern Railway Maintenance Infrastructure |url=https://www.researchgate.net/figure/An-example-of-a-Flat-Bottom-set-of-BR-Type-Scarf-breather-switches-4_fig4_303805760 |website=Researchgate}}</ref>

{{Gallery
|align=center |width=350 |state=expanded
|File:NYCSub ExpJoint.jpg|Expansion joint on [Williamsburg Bridge](/source/Williamsburg_Bridge), [New York City Subway](/source/New_York_City_Subway)
|File:MODULE 8.jpg|A breather switch on a [TGV](/source/TGV) line
|File:Expansion joint, Hayle.jpg|An expansion joint on the [Cornish Main Line](/source/Cornish_Main_Line), England
}}

==References==
{{reflist}}
* [https://www.lboro.ac.uk/news-events/news/2015/september/repoint-railway-safety.html Loughborough University unveils breakthrough technology with potential to revolutionise the global rail industry 9 September 2015]

==External Websites==
* [https://www.voestalpine.com/railway-systems-australia/en/solutions/Expansion-Switches/ Voestalpine Expansion switches]
* [http://www.trackwork.co.uk/manufacturing/expansion-adjustment-breather-switches/ Breather switches]
* [https://trid.trb.org/view/1925421 Expanding our understanding of the not so insignificant rail expansion joint]
* [https://www.midasbridge.com/en/solutions/rail-structure-interaction/ Rail Structure interaction]

{{Rail tracks}}

{{DEFAULTSORT:Breather Switch}}
Category:Permanent way

{{Rail-transport-stub}}

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Adapted from the Wikipedia article [Breather switch](https://en.wikipedia.org/wiki/Breather_switch) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Breather_switch?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.