Monday, January 13, 2014

John Loudon McAdam, Colossus of Roads

by Regina Jeffers

John Loudon McAdam was born on September 21, 1756 in Ayrshire, Scotland. Somewhere between the ages of 14-16, he traveled to New York City to work in his uncle’s counting house. He was an “agent for prizes,” which meant McAdam disposed of goods taken by force in war or otherwise. Nowadays, he might be termed a “fence.” He returned to Scotland in 1783 a rich man, having known great success. McAdam bought an estate in Sauhrie, Ayrshire, and assumed a position of road trustee in his district. This was the beginning of McAdam’s “obsession” with roads.

At his own expense, McAdam began experimenting with road construction materials for the roads upon his estate. He had noted that bare, dry roads could easily sustain the weight of contemporary vehicles. The problem rested in keeping those roads dry. Therefore, he dispensed with the metalled roads developed by the Romans and concentrated on tightly packed layers of small stones. McAdam permitted the traffic on the roads to pack down the surface, adding aggregate when necessary to smooth out imperfections.

In John McAdam's own words…”That it is the native soil which really supports the weight of traffic; that while it is preserved in a dray state, it will carry any weight without sinking and that it does in fact carry the road and carriages also; that this native soil must be previously made quite dry and a covering placed over it in that dry state; that the thickness of the road should only be regulated by the quantity of material necessary to form such impervious covering and never by reference to its own power of carrying weight.”

Road building before McAdam’s improvement was extremely expensive. High quality stone slabs were required to be skillfully laid. Generally, contractors took short cuts, which saved initially on the cost, but were expensive to repair. For example, the contractor might build on the top of logs, with a covering of small stones. This would quickly collapse and require extensive repairs. With McAdam’s methods, the actual work of building the roads could be done by unskilled workers breaking stones to fit through the grading sieves.

Receiving a governmental appointment in 1798, McAdam arrived in Falmouth, Cornwall. There he set about making changes to the way roads were constructed. He suggested the roads should be higher than the adjoining ground to improve drainage. McAdam also suggested a road’s surface be changed: large rocks would be placed first, then smaller stones, and finally fine gravel or slag. “McAdam’s original recipe called for a compacted subgrade of crushed granite or greenstone designed to support the load, covered by a surface of light stone to absorb wear and tear and shed water to the drainage ditches. In modern macadam construction, crushed stone or gravel is placed on the compacted base course and bound together with asphalt cement or hot tar. A third layer to fill the interstices is then added and rolled. Cement-sand slurry is sometimes used as the binder.” (Meet the Inventor on

In 1815, McAdam was made surveyor general of the Bristol Turnpike System, where he placed his theories into practice. At the time, McAdam wrote Remarks on the Present System of Road-Making (1816) and Practical Essay on the Scientific Repair and Preservation of Roads (1819). In 1823, based on a parliamentary inquiry, public authorities adopted McAdam’s position on road construction, and by 1827, he was appointed Surveyor General of Metropolitan Roads of Great Britain.

“Macadamization,” as McAdam’s process was called, quickly spread to other countries, most noticeably, to the United States. By the end of the U.S. Civil War, macadam roads had become the standard of the day. Other engineers, most notably Richard Edgeworth, took McAdam’s ideas one step further. Edgeworth, for example, mixed the stone dust with water and used it to fill in gaps between the surface stones. This provided a smoother surface for the increasing number of fancy carriages found on British roads. Modern roads have replaced the water/dust binding with tar or bitumen to create asphalt. “The first bituminous pavement was laid in 1854, in Paris, but it wasn’t until the twentieth century, and the coming of the automobile, that ‘black top’ became common.”

This “water bound macadam” mixture brought McAdam’s name into the English language. In 1825, the philosopher Jeremy Bentham wrote, “MacAdam’s system justified the perpetuation of MacAdam’s name in popular speech.” This was a bit ironic in the aspect that McAdam had openly condemned Edgeworth’s variation.

McAdam was offered a knighthood for his work, but he declined the offer. However, his grandson (William Junior) accepted the honour after John’s death on November 26, 1836, in Moffat, Dumfriesshire.


Regina Jeffers is the author of several Austen-inspired novels, including Darcy’s Passions, Darcy’s Temptation, Vampire Darcy’s Desire, Captain Wentworth’s Persuasion, The Phantom of Pemberley, Christmas at Pemberley, The Disappearance of Georgiana Darcy, Honor and Hope and The Mysterious Death of Mr. Darcy. She also writes Regency romances: The Scandal of Lady Eleanor, A Touch of Velvet, A Touch of Cashémere, A Touch of Grace, A Touch of Mercy, A Touch of Love and The First Wives’ Club. A Time Warner Star Teacher and Martha Holden Jennings Scholar, Jeffers often serves as a consultant in language arts and media literacy.

Twitter – @reginajeffers
Facebook – Regina Jeffers
(Books available from Amazon, Barnes & Noble, Books-a-Million, Joseph Beth, and Ulysses Press.)

The Phantom of Pemberley – SOLA’s Fifth Annual Dixie Kane Memorial Awards – 3rd Place – Romantic Suspense
Darcy’s Temptation – 2009 Booksellers’ Best Award Finalist – Long Historical
The Scandal of Lady Eleanor – Write Touch Readers’ Award – 2nd Place – Historical Romance
A Touch of Grace – SOLA’s Seventh Annual Dixie Kane Memorial Awards – 3rd Place – Historical Romance
The First Wives’ Club – SOLA’s Seventh Annual Dixie Kane Memorial Awards – Honorable Mention – Historical Romance
Christmas at Pemberley – 2011 Booksellers’ Best Award Finalist – Inspirational Romance; Second Place, General Fiction, New England Book Festival
The Mysterious Death of Mr. Darcy – SOLA’s Eighth Annual Dixie Kane Awards – Honorable Mention – Romantic Suspense
Angel and the Devil Duke – SOLA’s Eighth Annual Dixie Kane Awards – 3rd Place- Historical Romance


  1. I liked this, Regina ~ very interesting! He must have been a humble man to decline a knighthood! Thanks for a great article!

  2. I like articles like this that make you think of something you take for granted everyday. Can you imagine a long ride on an old stone road pre tarmac in Jane Austen's day for example. A man to say a big thank you to!

  3. Great post, Regina!
    Thanks for all the info!

  4. Hi there Regina

    Thanks for your article.
    I think that the Knighthood was actually accepted by JLM's Second son James Nicoll McAdam. He was "knighted by King William IV at Whitehall on 26th March 1834." This was during JLM's lifetime as he died in 1836. He did have a grandson called William though :)

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  6. Ms Jeffers, a prize agent was no more a fence than an author is a forger. A prize agent's job was to look after the interests of wartime naval captains in claiming their prize money for captured enemy warships and head money for prisoners. Prizes acted as an incentive to naval people, and since the more one was at sea the more probable it was one was to took prizes, they needed someone on shore to act in their interests. A moderate read of Patrick O'Brian's Aubrey Maturin novels gives a good idea of hos the prizes and prize agents worked. O'Brian is of course the naval equivalent of Jane Austin and is writing about the Napoleonic wars and the Royal navy.


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