Editing Macadam (section)

==Tar-bound macadam==
{{Main article|Tarmacadam}}
{{anchor | Tar | Bitumen }}
[[File:construction tar macadam.jpg|thumb|right|New macadam road construction at McRoberts, Kentucky: pouring tar. 1926]]

With the advent of [[motor vehicle]]s, dust became a serious problem on macadam roads. The area of low air pressure created under fast-moving vehicles sucked dust from the road surface, creating dust clouds and a gradual unraveling of the road material.<ref>[[Carl H. Claudy|Claudy, C.H.]] "[https://books.google.com/books?id=NLvPAAAAMAAJ The Right Road—and Why]," The Independent, New York, Volume 99, July, August, September 1919, 228. Retrieved on 2009-11-3.</ref> This problem was approached by spraying [[tar]] on the surface to create tar-bound macadam. In 1902 a Swiss doctor, [[Ernest Guglielminetti]], came upon the idea of using tar from [[Monaco]]'s gasworks for binding the dust.<ref name="sma-viatop.com">{{Cite web | title = History of asphalt road construction – Tar road construction | url = http://sma-viatop.com/SMAviatop_engl/history/teerstrassenbau.shtml?navid=9 | access-date = 31 July 2013 | archive-date = 13 November 2013 | archive-url = https://web.archive.org/web/20131113020339/http://sma-viatop.com/SMAviatop_engl/history/teerstrassenbau.shtml?navid=9 | url-status = dead }}</ref> Later a mixture of [[coal tar]] and ironworks [[slag]], patented by [[Edgar Purnell Hooley]] as [[Tarmacadam|tarmac]], was introduced.

A more durable road surface (modern mixed [[Asphalt concrete|asphalt]] pavement), sometimes referred to in the U.S. as blacktop, was introduced in the 1920s. Instead of laying the stone and sand aggregates on the road and then spraying the top surface with binding material, in the asphalt paving method the aggregates are thoroughly mixed with the binding material and the mixture is laid all together.<ref name=AsphaltPaver>{{citation |author=Cavette, Chris |title=Asphalt Paver |work=[[eNotes]] |url=http://www.enotes.com/how-products-encyclopedia/asphalt-paver/printHistory |access-date=19 June 2010 }}{{Dead link|date=February 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> While macadam roads have been resurfaced in most [[developed country|developed countries]], some are preserved along stretches of roads such as the United States' [[National Road]].<ref name="jordanssurfacing.co.uk">{{Cite web  | title = The History Of The United States' National Road | date = 4 February 2021 | url = https://jordanssurfacing.co.uk/the-history-of-the-united-states-national-road/ | access-date = 4 February 2021 }}</ref>

Because of the historic use of macadam as a road surface, roads in some parts of the United States (such as parts of [[Pennsylvania]]) are referred to as macadam, even though they might be made of asphalt or [[concrete]].<!--Parochial: The misidentified relative - [[Tarmacadam|tarmac]] - can still be sometimes found in New England.--> Similarly, the term "tarmac" is sometimes colloquially applied to asphalt roads or aircraft [[runway]]s.<ref name=WSDOTPavementGuide>{{citation |author=Stephen T. Muench |author2=Joe P. Mahoney |author3=Linda M. Pierce |display-authors=etal |chapter=History |title=WSDOT Pavement Guide |publisher=[[Washington State Department of Transportation]] |chapter-url=http://training.ce.washington.edu/wsdot/Modules/01_introduction/01-2_body.htm |page=2 in Module 1: Welcome and Introduction |url=http://training.ce.washington.edu/wsdot/ |access-date=19 June 2010 |url-status=dead |archive-url=https://archive.today/20121213000917/http://training.ce.washington.edu/wsdot/ |archive-date=13 December 2012 }}</ref>