Final answer:
John McAdam, a Scottish engineer, was the designer after whom the macadamized roads were named. He created the macadamization process for building durable and smooth roads.
Step-by-step explanation:
The macadamized roads, often referred to as "Macadam", were named after their designer, John McAdam. John McAdam was a Scottish engineer who invented the process of macadamization for building roads with a smooth hard surface that would be more durable and less muddy than soil-based tracks. This technology was a significant advancement in the early 19th century and greatly improved transportation. John McAdam, a Scottish engineer, was the designer after whom the macadamized roads were named. He created the macadamization process for building durable and smooth roads.