John Loudon McAdam

Macadamization, developed by John Loudon McAdam in the early 19th century, involves building roads from compacted layers of small, uniformly broken stones laid on a properly drained, slightly raised base. McAdam's key insight was that stones needed to be broken to a specific size—small enough to interlock under traffic pressure—rather than using large rocks or soft earth as previous methods did.

Earlier methods, such as the French Pierre Perdue system, used large foundation stones buried in soil, which were expensive and difficult to maintain. McAdam eliminated the heavy foundation layer entirely, relying instead on compaction of smaller broken stones by traffic itself, which made his roads cheaper, faster to build, and easier to repair.

McAdam was appointed as General Surveyor of the Roads in Britain, a position that gave him direct authority over road construction and maintenance practices. He used this role to systematically implement his methods across the British road network, dramatically improving travel times and road durability during his tenure.

Yes, tarmacadam (later shortened to "tarmac") was developed in the early 1900s by Edgar Purnell Hooley, who added tar as a binding agent to macadam-surfaced roads. The name directly references McAdam's method, building on his principle of compacted broken stone while adding a tar matrix to reduce dust and improve durability for motor vehicles.