Scottish civil engineer
John Loudon McAdam was a Scottish civil engineer and road-builder. He was the inventor of “macadamisation”, an effective and economical method of constructing roads.
John Loudon McAdam, a Scottish inventor of the macadam road surface.
John Loudon McAdam was the youngest of 10 children of James McAdam and Susanna Cochrane. He was born in Ayr before the family moved to Lagwyne Castle. When this burned down they moved to Blairquhan Castle, also in Ayrshire. John was educated at McDoick’s School of Maybole until 1770 when, at the age of 14, his father’s business, the Bank of Ayr, and the family fortune both collapsed, and his father died.
McAdam was sent to live with his uncle, a wealthy merchant in New York. During the American Revolution between 1775 and 1783, John Loudon McAdam supported the loyalist side. He went on to make his own fortune at a very young age, becoming a successful merchant, part owner of the privateering ship “General Matthew”, and a “prize agent”: in effect selling goods and material captured during the war and taking a cut for doing so.
He returned to Scotland with a considerable fortune in 1783. There he purchased an estate at Sauhrie, Ayrshire. McAdam, who had become a road trustee in his district, noted that the local highways were in poor condition. At his own expense he undertook a series of experiments in road making.
In 1798 he moved to Falmouth, Cornwall, where he continued his experiments under a government appointment. In 1816, as surveyor to the Bristol Turnpike Trust, he re-made their roads with a raised carriageway to improve drainage. Stones were graded and laid in three levels, with the smallest stones crushed and laid as a top surface. This provided swifter and safer travel. Later he added tarmacadam (“tarmac”, asphalt) to bind the top layer. His methods were adopted in many other countries. He was appointed surveyor general of the Bristol roads, he put his theories into practice. To document his work, McAdam wrote Remarks on the Present System of Road-Making (1816) and Practical Essay on the Scientific Repair and Preservation of Roads (1819).
As the result of a parliamentary inquiry in 1823 into the whole question of road making, his views were adopted by the public authorities, and in 1827 he was appointed Surveyor General of Metropolitan Roads in Great Britain. Macadamization of roads did much to facilitate travel and communication. The process was quickly adopted in other countries, notably the United States.