In modern construction, a combination of ___ and ____ is most often used for freeway overpasses.

• A. Concrete and Glass
• B. Wood and Stone
• C. Steel and Asphalt
• D. Concrete and steel

Answer: (D)

Modern freeway overpasses rely on a combination of materials that play to their strengths: steel handles tension and allows long spans and efficient fabrication, while concrete provides strong compression capacity, durability, and a smooth deck surface. In practice, you’ll see steel girders or a steel frame supporting a concrete deck, or prestressed concrete members with steel reinforcement, forming a steel–concrete system. This pairing gives the structure the necessary stiffness, strength, and longevity for high-speed, heavy-traffic use. Other material pairings listed don’t meet the typical structural requirements or are used mainly for non-structural roles (for example, asphalt is pavement, not a primary structural material).