John MacAdam

He returned to Scotland in 1783. MacAdam purchased an estate at Sauchrie, Ayrshire and started experimenting with a new method of road construction. When he was appointed surveyor to the Bristol Turnpike Trust[?] in 1816 he remade the roads under his control with crushed stone bound with gravel on a firm base of large stones. A camber, making the road slightly convex, ensured the rainwater rapidly drained off the road and did not penetrate the foundations. This way of building roads later became known as the Macadamized system[?].

As a result of his success, MacAdam was made surveyor-general of metropolitan roads in England. By the end of the 19th century, most of the main roads in Europe were built in this way. John MacAdam died at Moffat, Scotland.

Modern road surfaces are still largely dependent on MacAdam's discovery. Coal tar was first used to bind the stones together, hot-laid tarred aggregate or tar-sprayed chips providing an excellent road-metalling for the surface. Oil-based asphalt from Trinidad and Tobago and from refineries was later used as a road surfacing, laid on reinforced concrete, but still owes a lot to MacAdam as it is mixed with granite or limestone chippings. This process became known as Tarmacadam[?] (a short form of which is used to refer to airplane runways: "tarmac").

MacAdam never really achieved the respect that was his due. He was paid the sum of £5,000 for works done for Turnpike Trusts around Bristol, but a proposal for £5,000 from Parliament as a grant for his expenses was first refused, then cut to £2,000, mainly due to professional jealousy. Corruption in roadworks was appalling; by his own efficiency, MacAdam exposed the abuse of road tolls by less scrupulous Turnpike Trusts, many of which were run at a deliberate loss despite high toll receipts. Travellers of all kinds respected MacAdam, but those whose scams he had revealed remained his bitter enemies. His reputation has nevertheless survived, as the Scotsman who paved the way for development.