Three points A, B and C 500 m apart on a straight road have 500 m, 505 m and 510 m as their reduced levels. The road is said to have

Highway engineering (also known as roadway engineering and street engineering) is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods. (Source: Wikipedia)