John Loudon McAdam

Who was John Loudon McAdam?

John Loudon McAdam was a Scottish engineer and road-builder. He invented a new process, "macadamisation", for building roads with a smooth hard surface that would be more durable and less muddy than soil-based tracks.

Modern road construction still reflects McAdam's influence. Of subsequent improvements, the most significant was the introduction of tar to bind the road surface's stones together – "tarmac" – followed later by the use of hot-laid tarred aggregate or tar-sprayed chippings to create better road metalling. More recently, oil-based asphalt laid on reinforced concrete has become a major road surface, but its use of granite or limestone chippings still recalls McAdam's innovation.