Editing Macadam (section)

==Advent of macadam==
[[File:John Loudon McAdam, 1830, National Gallery, London.JPG|thumb|John Loudon McAdam]]
===John McAdam===
John Loudon McAdam was born in [[Ayr]], Scotland, in 1756. In 1787, he became a trustee of the Ayrshire Turnpike in the [[Scottish Lowlands]] and during the next seven years his hobby became an obsession. He moved to [[Bristol]], England, in 1802 and became a Commissioner for Paving in 1806.<ref name="Bio"/> On 15 January 1816, he was elected [[surveyor general]] of roads for the Bristol [[turnpike trust]] and was responsible for 149 miles of road.<ref name="Bio"/> He then put his ideas about road construction into practice, the first 'macadamised' stretch of road being Marsh Road at Ashton Gate, Bristol.<ref name="Bio">A. W. Skempton (2002). A Biographical Dictionary of Civil Engineers in Great Britain and Ireland: 1500–1830. p.416. Thomas Telford, 2002</ref> He also began to actively propagate his ideas in two booklets called ''Remarks (or Observations) on the Present System of Roadmaking'', (which ran nine editions between 1816 and 1827) and ''A Practical Essay on the Scientific Repair and Preservation of Public Roads,'' published in 1819.<ref name=McAdam1824>{{citation |year=1824 |author=McAdam, John Loudon |title= Remarks on the Present System of Road Making; With Observations, Deduced from Practice and Experience |edition=8th |place= London |publisher= Longman, Hurst, Rees, Orme, and Brown, Paternoster Row |url=https://books.google.com/books?id=a9RMAAAAYAAJ |access-date=26 September 2011}}</ref>

===McAdam's methods===
[[File:macadam road 1850s.jpg|thumb|A macadam road in [[Nicolaus, California]], {{circa|1850s}}]]
McAdam's method was simpler yet more effective at protecting roadways: he discovered that massive foundations of rock upon rock were unnecessary and asserted that native soil alone would support the road and traffic upon it, as long as it was covered by a road crust that would protect the soil underneath from water and wear.<ref name=ColossusofRoads>{{citation |author=Craig, David|title=The Colossus of Roads |work=Palimpsest |publisher=Strum.co.uk |url=http://www.strum.co.uk/palimps/macadam.htm |access-date=18 June 2010}}</ref> An under-layer of small angular broken stones would act as a solid mass. Keeping the surface stones smaller than the width of a wheel made for a good running surface. The small surface stones also provided low stress on the road, so long as it could be kept reasonably dry.<ref name=Lay1992pp76-77>Lay (1992), pp. 76–77</ref>

Unlike Telford and other road builders of the time, McAdam laid his roads almost level. His {{convert|30|ft|m|adj=mid|-wide}} road required a rise of only {{convert|3|in|cm}} from the edges to the centre. Cambering and elevation of the road above the [[water table]] enabled rain water to run off into ditches on either side.<ref name=McAdam1824p38>McAdam (1824), p. 38</ref>

Size of stones was central to McAdam's road building theory. The lower {{cvt|20|cm|in|0|adj=on|order=flip}} road thickness was restricted to stones no larger than {{convert|7.5|cm|in|0|order=flip}}. The upper {{convert|5|cm|in|adj=mid|0|-thick|order=flip}} layer of stones was limited to stones {{convert|2|cm|in|frac=8}} in diameter; these were checked by supervisors who carried scales. A workman could check the stone size himself by seeing if the stone would fit into his mouth. The importance of the 2&nbsp;cm stone size was that the stones needed to be much smaller than the {{convert|4|in|cm|0|spell=in|adj=on}} width of the iron [[carriage]] wheels that travelled on the road.<ref name=Lay1992p75/>

McAdam believed that the "proper method" of breaking stones for utility and rapidity was accomplished by people sitting down and using small hammers, breaking the stones so that none of them was larger than {{convert|6|oz|g|-1|spell=in}} in weight. He also wrote that the quality of the road would depend on how carefully the stones were spread on the surface over a sizeable space, one shovelful at a time.<ref name=McAdam1824pp39-40>McAdam (1824), pp. 39–40</ref>

McAdam directed that no substance that would absorb water and affect the road by frost should be incorporated into the road. Neither was anything to be laid on the clean stone to bind the road. The action of the road traffic would cause the broken stone to combine with its own angles, merging into a level, solid surface that would withstand weather or traffic.<ref name=McAdam1824p41>McAdam (1824), p. 41</ref>

===North America===
The first macadam road built in the United States was constructed between [[Hagerstown, Maryland|Hagerstown]] and [[Boonsboro, Maryland]], and was named at the time Boonsborough [[Toll road|Turnpike]] Road. This was the last section of unimproved road between [[Baltimore]] on the [[Chesapeake Bay]] to [[Wheeling, West Virginia|Wheeling]] on the [[Ohio River]]. Before it was macadamized, stagecoaches travelling the Hagerstown to Boonsboro road in the winter had taken 5 to 7 hours to cover the {{convert|10|mi|adj=on}} stretch.<ref name=ElectricScotland>{{citation |title=John Loudon MacAdam |work=Significant Scots |publisher=ElectricScotland.com |url= https://www.electricscotland.com/history/other/macadam_john.htm |access-date=2017-02-13}}</ref><ref name=curbstone>{{cite web |url=https://curbstone.com/_macadam.htm |title=1823 – First American Macadam Road |access-date=2017-02-13 |archive-url=https://web.archive.org/web/20201127012227/https://curbstone.com/_macadam.htm |archive-date=27 November 2020 |url-status=dead}}</ref> 

This road was completed in 1823, using McAdam's road techniques, except that the finished road was compacted with a cast iron roller instead of relying on road traffic for compaction.<ref>{{cite web |url=http://www.town.boonsboro.md.us/index.asp?SEC=E4DE0ECB-A02E-4603-8279-BAF21E62BC37 |title=The History of Boonsboro |access-date=2017-02-13}}</ref> The second American road built using McAdam principles was the [[National Road|Cumberland Road]] which was {{convert|73|mi}} long and was completed in 1830 after five years of work.<ref name=ElectricScotland/><ref name=curbstone/>

===McAdam's influence===
McAdam's renown is his effective and economical construction, which was a great improvement over the methods used by his generation. He emphasised that roads could be constructed for any kind of traffic, and he helped to alleviate the resentment travellers felt toward increasing traffic on the roads. His legacy lies in his advocacy of effective road maintenance and management. He advocated a central road authority with trained professional officials who could be paid a salary that would keep them from corruption. These professionals could give their entire time to these duties and be held responsible for their actions.<ref name=OFlaherty2002>{{citation |year=2002 |author= O'Flaherty, Coleman A |title=Highways: the Location, Design, Construction and Maintenance of Road Pavements |edition=4th |place= Woburn, MA |publisher=Butterworth-Heinemann |page=228 |isbn=0-7506-5090-7|url=https://books.google.com/books?id=Ren4sWQ3jKkC&q=%22whilst+mcadam%22&pg=PA228 |access-date=18 June 2010}}</ref>