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Issue 62 - John Loudon McAdam

Scotland Magazine Issue 62
April 2012


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John Loudon McAdam

The surveyor-general of metropolitan roads

Did you know that the smooth durability of modern roads is due to a process known as ‘macadamisation’? John Loudon McAdam changed our roads forever and both his product and his name have become a part of our culture.

He was born in Ayr on 21 September, 1756, the 10th child of parents James McAdam and Susanna Cochrane.

He was born an aristocrat, if a minor one, but his father was both unlucky and unwise in his investments. Not only did James McAdam lose a fortune in banking, but he also built a new home – Lagwyne Castle – which burned to the ground soon after.

When John Loudon’s father died in 1770, the 14 year old boy was packed off to New York to the care of his Uncle William, a childless merchant.

John did well in New York at first. He worked at his uncle’s counting house and then went into business for himself.

In 1778 John married Gloriana Nicoll. He profited from the American Revolution by selling goods that had been seized from the enemy.

But the war did not go his way, and in 1783 most of his property and assets were stripped from him, and he returned home to Scotland with his family.

He had held onto enough money to buy an estate at Sauchrie near Maybole, close to where he had gone to school.

His aristocratic connections helped him and for some time he had a controlling interest in a company that manufactured coal products such as tar for sealing ships.

His first experiments in the road-building arena were at his own expense, improving the road to his property.

John Loudon settled well into the life of local dignitary and entrepreneur. He became the deputy lieutenant of the county, a magistrate, the officer in charge of a volunteer artillery corps, and a trustee of the Ayrshire turnpike roads.

Initially it was a job for the Navy that took him to England, but in 1815 he was appointed surveyor for the Bristol Turnpike Trust and he moved his family to Bristol.

This is where John Loudon’s career as we know it really took off. He developed his ideas for road construction in the Bristol area, and presented his evidence to Parliament in the form of two papers: Remarks on the Present System of Road-Making and Practical Essay on the Scientific Repair and Preservation of Roads.

His method might seem obvious now: crushed stone in layers, bound together by fine gravel or slag, and cambered so that water would drain off.

But this was by far the greatest advance in British road building since the Romans left in the 4th century AD, so it did not go unnoticed.

Before long, John Loudon was the consultant surveyor for some 70 turnpike trusts across Great Britain. His sons followed him into the business, as ‘macadmisation’ or ‘macadam’ became the accepted way to build a modern road.

It was another man, E. Purnell Hooley who, in 1901, patented a version of John Loudon’s process called ‘Tar Macadam’. This simply added a layer of tar to the road surface to bind the stones together. And so tarmac was born.

John Loudon didn’t get to keep hold of his patented method.

It quickly spread to Europe and America. But his achievements were nonetheless well rewarded and he was made surveyor-general of metropolitan roads in Great Britain. He was also offered a knighthood, which he passed on to his son due to his own old age.

John’s wife Gloriana died in 1825 and two years later he married Anne Charlotte Delancey, who was 30 years his junior and a relative of his first wife.

This must have come as something of a shock to John Loudon’s family, but he lived out his remaining years without major incident, dying at Moffat on 26 November, 1836, aged 80 years.

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