John Loudon McAdam
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John Loudon McAdam (born September 21, 1756 in Ayr; died November 26, 1836 in Moffat) was a Scottish engineer and road-builder. He invented a new process, "macadamisation", for building roads with a smooth hard surface that would be more durable and less muddy than soil-based tracks.
McAdam moved to New York in 1770 and, as a merchant and prize agent during the American Revolution, made his fortune working at his uncle's counting house. He returned to Scotland in 1783 and purchased an estate at Sauchrie, Ayrshire.yup
His experiences trying to manage and move about his estate prompted him to consider and research how road construction might be improved. In two treatises written in 1816 and 1819 (Remarks on the Present System of Road-Making and Practical Essay on the Scientific Repair and Preservation of Roads) he argued that roads needed to be raised above the surrounding ground and constructed from layered rocks and gravel in a systematic manner. McAdam had also been appointed surveyor to the Bristol Turnpike Trust in 1816, where he decided to remake the roads under his care with crushed stone bound with gravel on a firm base of large stones. A camber, making the road slightly convex, ensured rainwater rapidly drained off the road rather than penetrate and damage the road's foundations. This construction method, the greatest advance in road construction since Roman times, became known as "macadamization", or, more simply, "macadam".
The macadam method spread very quickly across the world. The first macadam road in North America, the National Road, was completed in the 1830s and most of the main roads in Europe were macadamized by the end of the nineteenth century.
Although McAdam was paid £5,000 for his Bristol Turnpike Trust work and made "Surveyor-General of Metropolitan Roads" in 1827, professional jealousy cut a £5,000 grant for expenses from the Parliament of the United Kingdom to £2,000 in 1820. His efficient road-building and management work had revealed the corruption and abuse of road tolls by unscrupulous Turnpike Trusts, many of which were run at a deliberate loss despite high toll receipts.
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[edit] Legacy
Modern road construction still reflects McAdam's influence. Of subsequent improvements, the most significant was the introduction of tar (originally coal tar) to bind the road surface's stones together – "tarmac" (for Tar Macadam) – followed later by the use of hot-laid tarred aggregate or tar-sprayed chippings to create better road metalling. More recently, oil-based asphalt laid on reinforced concrete has become a major road surface, but its use of granite or limestone chippings still recalls McAdam's innovation.
[edit] Descendants
One of John Loudon McAdam’s descendants was the World War Two general, Sir Richard McCreery. His mother was Emilia McAdam, a direct descendant of the engineer.
[edit] Reference
Devereux, Roy (1936). John Loudon McAdam: Chapters in the History of Highways. London: Oxford University Press.
[edit] External links
- Remarks on the Present System of Road Making by John Loudon McAdam, 1821, from Google Book Search
- about.com
- maybole.com
- see-scotland.com
- [1]
