Anatomy of the Highway

By June 10, 2018 No Comments

Daily, we drive America’s highways, but most of us aren’t aware of the many intricate parts that make up the road beneath our feet; we take the road for granted. However, highways are complex structures, they are wholistic and include the infrastructure and environment that surround them.

The surface of the road is called the Travelway. A Travelway is the area dedicated to the movement of vehicles. It’s the portion of road that’s most noticeable and elicits comments like “smooth ride” and “darn potholes!”

The Travelway is constructed of pavement. Pavement refers to the “semi-durable surface of the Travelway,” and may be constructed of dirt, gravel, wood, stone, brick, macadam, concrete or asphalt, although most often asphalt and concrete are used for high traffic roads and macadam for pedestrian streets.

Another aspect of the Travelway is Alignment. Alignment possesses two elements: horizontal and vertical. Horizontal Alignments refers to the road’s curve, does it wind like a river or is it straight?

Vertical Alignment refers to the road’s slope. Does it climb a mountain or traverse a prairie?

Each road possesses a Crown. The road’s Crown is the arc of the road. Is the road raised in the center to allow drainage?

The curb is the raised area at the edge of the road. It provides a barrier between the Travelway and the surrounding environment. Beyond the curb is where pedestrians roam.

Many roads have a Swale. The ditch alongside the road that collects water. Theses ditches may be shallow or deep depending on rainfall. They protect the road from flooding.

Beneath the Pavement lies the Subsurface. The Subsurface is a stabilized base. The subsurface interfaces the Earth and the Pavement. It’s the Subsurface that causes structural stability.

Structures are the tunnels, culverts tollbooths and retaining walls. These structures serve a function and give each street its’ unique flavor. Some lesser seen structures are rest stops, border patrol stations, and agricultural checkpoints.

The combination of these elements, the natural world, and local architecture make for the scenic views seen from America’s highways. Each road possesses a feeling; a culmination of all of these elements. City Planners take all these elements into consideration while designing a road. Next time you set out on the open road, take a moment to consider all the elements that created that road.

Sourced from Historic Roads

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