A History of American Roadways

October 24, 2011

presented by McDonald Paving of Spokane

The roadway has remained paramount in the United States of America since the time of its independence, with the issue of road building serving as a hot political topic as far back as the time of John Adams and Thomas Jefferson. The development of private roads, known as turnpikes, formed the backbone of the U.S. roadway system throughout the early 19th century. Paving the roads remained a major expense in the early days of the republic, so turnpike companies often resorted to the creation of plank roads, which used wooden planks to minimize rolling resistance for carriages and kept them from getting stuck in the mud after a wet weather period.

The first major technological advance in paving roads in the United States came from Scotland and caught on around 1820. Engineer John Loudon McAdam developed the technique of road building that would be named for him by combining aggregate materials such as stone and gravel and compacting them with a roller. The small aggregate stones allowed for the iron carriage tires of the time to travel smoothly. By the 1830s, many of America’s roads had undergone macadamization using the combination of stone dust and water as a binding agent, creating what is known as water-bound macadam.

While this process served the horse and carriage of the 19th century well, the fast speed of the motor vehicle created dust clouds on macadamized roads. To solve this problem, engineers used tar as a binding agent, creating what they called tar-bound macadam. U.S. engineer Edgar Purnell Hooley later developed a road-surface mixture of ironworks slag and coal tar, called tarmac, which proved to be more resilient. Finally, the use of bitumen as a binding agent allowed for the development of asphalt concrete. Road pavers around the world, including McDonald Paving of Spokane, continue to use asphalt concrete as a primary construction material today.


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