John Loudon McAdam was a
ScottishScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
engineerAn engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
and
roadA road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
-builder. He invented a new process, "
macadamMacadam is a type of road construction pioneered by the Scotsman John Loudon McAdam in around 1820. The method simplified what had been considered state-of-the-art at that point...
isation", for building roads with a smooth hard surface that would be more durable and less muddy than
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
-based tracks.
Modern road construction still reflects McAdam's influence. Of subsequent improvements, the most significant was the introduction of
tarTar is modified pitch produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden vessels against rot. The largest...
(originally
coal tarCoal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...
) to bind the road surface's stones together – "
tarmacTarmac is a type of road surface. Tarmac refers to a material patented by Edgar Purnell Hooley in 1901...
" (for Tar Macadam) – followed later by the use of hot-laid tarred
aggregateAggregate is the component of a composite material that resists compressive stress and provides bulk to the composite material. For efficient filling, aggregate should be much smaller than the finished item, but have a wide variety of sizes...
or tar-sprayed chippings to create better
road metallingThe term road metal refers to the crushed rock used for road beds, surfaces, 'all-weather' walkways and paths, foundations, and railway embankments, among other things. The use of road metal dates back to antiquity.-History:...
. More recently,
oilPetroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
-based
asphaltAsphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...
laid on
reinforced concreteReinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
has become a major road surface, but its use of granite or
limestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
chippings still recalls McAdam's innovation.
Early life
McAdam was born in
AyrAyr is a town and port situated on the Firth of Clyde in south-west Scotland. With a population of around 46,000, Ayr is the largest settlement in Ayrshire, of which it is the county town, and has held royal burgh status since 1205...
,
ScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. 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 IJames I, King of Scots , was the son of Robert III and Annabella Drummond. He was probably born in late July 1394 in Dunfermline as youngest of three sons...
's reign. He moved to
New YorkNew York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
in 1770 and, as a
merchantA merchant is a businessperson who trades in commodities that were produced by others, in order to earn a profit.Merchants can be one of two types:# A wholesale merchant operates in the chain between producer and retail merchant...
and prize agent during the
American RevolutionThe American Revolution was the political upheaval during the last half of the 18th century in which thirteen colonies in North America joined together to break free from the British Empire, combining to become the United States of America...
, made his fortune working at his uncle's
counting houseA counting house, or compting house, literally is the building, room, office or suite in which a business firm carries on operations, particularly accounting. By a synecdoche, it has come to mean the accounting operations of a firm, however housed...
. He returned to Scotland in 1783 and purchased an estate at Sauchrie,
AyrshireAyrshire is a registration county, and former administrative county in south-west Scotland, United Kingdom, located on the shores of the Firth of Clyde. Its principal towns include Ayr, Kilmarnock and Irvine. The town of Troon on the coast has hosted the British Open Golf Championship twice in the...
.
Road builder
McAdam became a trustee of the Ayrshire Turnpike in 1783 and became increasingly involved with day-to-day road construction over the next 10 years. In 1812 he moved to
BristolBristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
, England and he became general surveyor for the Bristol Corporation in 1804. He put forward his ideas in evidence to
ParliamentaryThe Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...
enquiries in 1810, 1819 and 1823. In two
treatiseA treatise is a formal and systematic written discourse on some subject, generally longer and treating it in greater depth than an essay, and more concerned with investigating or exposing the principles of the subject.-Noteworthy treatises:...
s 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 TrustTurnpike trusts in the United Kingdom were bodies set up by individual Acts of Parliament, with powers to collect road tolls for maintaining the principal highways in Britain from the 17th but especially during the 18th and 19th centuries...
in 1816, where he decided to remake the roads under his care with crushed
stoneIn geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
bound with gravel on a firm base of large stones. A
camberCamber may refer to a variety of curvatures and angles:* Camber angle, the angle made by the wheels of a vehicle* Camber thrust in bike technology* In the steel industry, the concavity of rolls...
, 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
RomanAncient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
times, became known as "macadamisation", or, more simply, "
macadamMacadam is a type of road construction pioneered by the Scotsman John Loudon McAdam in around 1820. The method simplified what had been considered state-of-the-art at that point...
".
The macadam method spread very quickly across the world. The first macadam road in
North AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, the
National RoadThe National Road or Cumberland Road was the first major improved highway in the United States to be built by the federal government. Construction began heading west in 1811 at Cumberland, Maryland, on the Potomac River. It crossed the Allegheny Mountains and southwestern Pennsylvania, reaching...
, was completed in the 1830s and most of the main roads in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
were macadamized by the end of the nineteenth century.
Although McAdam was paid
£The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence...
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 KingdomThe Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...
to £2,000 in 1827. His efficient road-building and management work had revealed the corruption and abuse of
road tollA toll road is a privately or publicly built road for which a driver pays a toll for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds...
s by unscrupulous Turnpike Trusts, many of which were run at a deliberate loss despite high toll receipts.
Death and descendants
McAdam died in
MoffatMoffat is a former burgh and spa town in Dumfries and Galloway, Scotland, lying on the River Annan, with a population of around 2,500. The most notable building in the town is the Moffat House Hotel, designed by John Adam...
,
DumfriesshireDumfriesshire or the County of Dumfries is a registration county of Scotland. The lieutenancy area of Dumfries has similar boundaries.Until 1975 it was a county. Its county town was Dumfries...
, while returning to his home in
HoddesdonHoddesdon is a town in the English county of Hertfordshire, situated in the Lea Valley. The town grew up as a coaching stop on the route between Cambridge and London. It is located southeast of Hertford, north of Waltham Cross and southwest of Bishop's Stortford. At its height during the 18th...
,
HertfordshireHertfordshire is a ceremonial and non-metropolitan county in the East region of England. The county town is Hertford.The county is one of the Home Counties and lies inland, bordered by Greater London , Buckinghamshire , Bedfordshire , Cambridgeshire and...
, from his annual summer visit to Scotland. His three sons, and in turn four grandsons, followed him into the profession and assisted with the management of turnpike trusts around the country. His second surviving son, James Nicholl McAdam, the "Colossus of Roads", was knighted for managing turnpike trusts—a knighthood, it is said, previously offered to his father but declined.
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