McAdam, John Loudon

McAdam, John Loudon (1756-1836), engineer, b. Ayr, Scotland.

John Loudon McAdam was one of the great road builders of the 18th century.

Before his time, the roads of Britain were badly made and always in a poor state of repair.

McAdam began building roads near Bristol in 1816. He had the idea that broken stones with rough corners would bind themselves together and this is what he used to make his roads.

The more they were used, the tighter these roads became bound and the effect of rain also was to bind them even tighter. The word 'macadam' is now used to mean 'a road surface made of closely-packed broken stone'. Today tarmac (tar-macadam) roads are more common. Crushed rock is placed on the road-bed and packed down firmly and a layer of asphalt or tar and granite chipping is placed over the top. McAdam was placed in charge of the roads in London in 1827.

See John Loudon McAdam Remarks On The Present System Of Road Making: With Observations, Deduced From Practice And Experience, With A View To The Revision Of The Existing Laws (1823)