Everything about John Loudon Mcadam totally explained
John Loudon McAdam (
September 21 1756 -
November 26 1836) 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.
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.
Early life
McAdam was born in
Ayr,
Scotland. He was the youngest of ten children and second son of the Baron of Waterhead. The family name had traditionally been McGregor, but was changed to McAdam (claiming descent from the Biblical
Adam) for political reasons in
James I's reign. He 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.
Road builder
McAdam became a trustee of the Ayrshire Turndike in
1783 and became increasingly involved with day-to-day road construction over the next 10 years. In 1812 he moved to
Bristol, England and he became general surveyor for the Bristol Corporation in 1804. He put forward his ideas in evidence to
Parliamentary enquiries in
1810,
1819 and
1823. 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
1820, professional jealousy cut a £5,000 grant for expenses from the
Parliament of the United Kingdom to £2,000 in
1827. 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.
Death and descendants
McAdam died in
Moffat,
Dumfries and Galloway, Scotland. 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.
Further Information
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