A road WHAT IS A ROAD is a hard flat surface that people travel on Roads make it easier to move from one place to another About 2,000 years ago the ancient Romans built the first large system of roads There were Roman roads throughout Europe Africa and the Middle East Then about 600 years ago the Incas built a road system in South America ROMAN ROAD INCAN ROAD
MODERN ROADS Road building methods have changed a lot since ancient times In the 1900s the invention of the car led to many road improvements Roads needed to be stronger to support the faster heavier traffic of cars and trucks Today there are millions of miles of roads to take you wherever you want to go
ROAD CONSTRUCTION Roads are built in layers First the ground is leveled to create a roadbed Then layers of gravel are added Big machines roll over the gravel to pack it down Finally layers of either asphalt or concrete are added ASPHALT SURFACE ASPHALT BASE CONCRETE SLAB GRAVEL ROADBED ASPHALT PAVEMENT CONCRETE PAVEMENT
POURING CONCRETE Concrete is sand and gravel mixed with cement Road workers pour concrete when it is wet They pour the concrete into molds called forms The forms hold the concrete in place while it dries Special machines smooth the concrete so it dries evenly SPREADING ASPHALT Asphalt is sand and gravel mixed with a black sticky substance called bitumen Workers heat the asphalt and spread it on the road while it's hot Then machines roll over the asphalt to smooth it out When the asphalt cools it becomes a hard surface
