wheel–rail interface

{{Short description|Contact area between wheel and rail of railway}}The wheel–rail interface is the area of contact between wheels and rails of railways.{{cite journal|last=Tuzik|first=Bob|title=Taking the Long View: 20 years of Wheel/Rail Interaction (Part 1 of 2) |url=http://interfacejournal.com/archives/882 |journal=Interface: The Journal of Wheel/Rail Interaction|date=8 January 2014}} The interaction between wheel and rail is a specialized subject covering the design and management of the high stresses in the small contact area between a steel wheel and a steel rail. The focus is on safety improvement, maintenance and replacement costs reduction, downtime reduction, and energy and environmental management.{{cite web|last=Fröhling |first=Robert |title=Wheel/Rail Interface Management in South Africa – The Past and the Future |url=http://globalview.uic.asso.fr/cd-rom3_sans/2008_06_30_spo_uic_global_view_workshop_rf.pdf |publisher=Transnet Freight Rail |accessdate=21 January 2014 |archiveurl=https://web.archive.org/web/20140201173349/http://globalview.uic.asso.fr/cd-rom3_sans/2008_06_30_spo_uic_global_view_workshop_rf.pdf |archivedate=February 1, 2014 |format=PDF}}{{cite web|title=Wheels and Bogies|archive-url=https://web.archive.org/web/20170223212618/http://www.railway-technical.com/whlbog.shtml|archive-date=23 February 2017|url=http://www.railway-technical.com/whlbog.shtml|publisher=Railway Technical Web Pages|accessdate=7 June 2019}} The surface of the wheel that rests on the rail is known as the tread. A wheel may have either a single flange on the gauge side of the rail or two flanges, one on each side of the rail.