Paving technology has advanced dramatically since the first paved roads allowed for wheeled carts. Over the years, builders have used everything from stone slabs to concrete. Some of the earliest roads included feats of engineering that would be difficult to implement, even today.
When looking at the evolution of roads, the feats of Ancient Rome still command attention. The Appian Way stretched for approximately 121 miles in a nearly straight line when first built in 312 B.C. Rome did not invent the road, but their dedication to infrastructure took road building technologies to new heights. Romans believed in straight lines, draining marshes, building bridges, and clearing forests to allow for road development.
Early Paving Techniques
Wheeled transport necessitated the development of paved roads, and human settlements as far back as 4000 B.C. show evidence of paving. Early techniques involved the use of gravel, cobblestone, brick, limestone, and other small pieces glued into place with an adhesive. Roman roads typically consisted of several layers. The underlayment would be a rough gravel designed to allow for drainage. On top, a layer of fine gravel allowed for transport. The top layer was often constructed using cut stone and limestone, creating a smooth road surface.
Invention of Asphalt
Today, most roads are paved using asphalt. While the substance is naturally occurring and has been used in roads as far back as 625 B.C., the substance in use today first hit the market in the 1800s. Thomas Telford laid more than 900 miles of road while perfecting the use of asphalt and broken stone to create a smooth road. In 1870, chemist Edmund DeSmedt laid the first sheet asphalt that would go on to become the most prominent paving material in America.
Roads in America
In America, the rapid adoption of bicycles led to the need for more paved roads. In 1908, when Ford released the inexpensive Model T, the need became even more apparent. Several bills designed to fund infrastructure went into effect. In 1921, the Federal Highway Act created the Bureau of Public Roads (BPR) and funded a two-lane highway system throughout the United States. It would be decades before this project was complete. In 1956, the Federal-Aid Highway Act expanded and funded continued highway development. In 1966, concerns about public transit, urban development, and environmental concerns led to the creation of the U.S. Department of Transportation (DOT). The BPR transitioned into the Federal Highway Administration under the DOT.
The federal government maintains the highway system, and local roads are maintained by city, county, and state government. Many government roadway construction and maintenance projects are outsourced to independent paving companies.