John Loudon McAdam (1756–1836)

McAdam was a British pioneer in the systematic construction and administration of roads. He devised a method of road-making that was economic and efficient and resulted in a network of roads suitable for fast horse carriages. His name became the word for a smooth and well-made road surface: ‘macadam’, or later ‘tarmacadam’ or ‘tarmac’.

He was born at Ayr in south-west Scotland. At the age of 14 he crossed the Atlantic to New York, where his uncle was a merchant. He succeeded in business there but left after the American War of Independence and returned to Scotland. He managed a colliery and went into business with the Earl of Dundonald in the British Tar Company, which made tar from coal to repair ships. In 1798 he moved to the port of Bristol, where he became surveyor for the city and was involved in several projects. His main interest was the Bristol Turnpike Trust, which was responsible for principal toll-roads in the area.

McAdam advised parliamentary enquiries on the condition of roads and wrote an influential book in 1816, Remarks on the Present System of Road Making. He said roads should be raised on top of well-drained ground with a camber to shed water. Surfaces should be made of broken stone that was graded from large at the base to small at the top and then compacted. He proposed that roads should be overseen by surveyors. Good roads on this system could be built quickly and cheaply and kept in repair, which was increasingly important for the fast delivery of mail across the country. The Bristol Turnpike Trust appointed him as their surveyor in 1815 and he repaired existing roads and extended the network to 128 km. He and his sons built roads in other parts of Britain and he became an influential advisor to the government on improvements nationally. His systems influenced practice in Europe and North America and were continued by his three sons and four grandsons.