Macadam roads pioneered by Scottish engineer
John Loudon McAdam in the 1820s are prone to rutting and generating dust. Methods to stabilise macadam surfaces with
tar date back to at least 1834 when John Henry Cassell, operating from ''Cassell's Patent Lava Stone Works'' in
Millwall, England, patented "lava stone." This method involved spreading tar on the
subgrade, placing a typical macadam layer, and finally sealing the macadam with a mixture of tar and sand. Tar-grouted macadam was in use well before 1900 and involved scarifying the surface of an existing macadam pavement, spreading tar and re-compacting. Although the use of tar in road construction was known in the 19th century, it was little used and was not introduced on a large scale until the motorcar arrived on the scene in the early 20th century. Ironically, although
John Loudon McAdam himself had been a supplier of coke for
Britain's first coal tar factory, he never in his own lifetime advocated for the use of tar as a binding agent for his road designs, preferring free-draining materials (see the page
Macadam). In 1901,
Edgar Purnell Hooley was walking in
Denby, Derbyshire, when he noticed a smooth stretch of road close to an ironworks. He was informed that a barrel of tar had fallen onto the road and someone poured waste
slag from the nearby furnaces to cover up the mess. Hooley noticed this unintentional resurfacing had solidified the road, and that there was no rutting and no dust.
Nottingham's Radcliffe Road became the first tarmac road in the world. In 1903 Hooley formed
Tar Macadam Syndicate Ltd and registered tarmac as a trademark. ==Later developments==